diff --git a/README.md b/README.md
index 7e678e2f0..1b76917f3 100644
--- a/README.md
+++ b/README.md
@@ -653,20 +653,23 @@ consistent formatting using the [`spotless`](https://github.com/diffplug/spotles
 
 ### Testing
 
-The library includes comprehensive **serialization round-trip tests** for examples published in the
+The library includes comprehensive **serialization round-trip and equality tests** for the example resources published in the
 following packages:
 
 - [hl7.fhir.r4.examples](https://simplifier.net/packages/hl7.fhir.r4.examples) (5309 examples)
 - [hl7.fhir.r4b.examples](https://simplifier.net/packages/hl7.fhir.r4b.examples) (2840 examples)
 - [hl7.fhir.r5.examples](https://simplifier.net/packages/hl7.fhir.r5.examples) (2822 examples)
 
-For each JSON example of a FHIR resource in the packages above, a test is performed with the
-following steps:
+For each JSON example of a FHIR resource in the referenced packages, two categories of tests are executed:
 
-1. Deserialization: The JSON is deserialized into the corresponding generated Kotlin resource class.
-2. Serialization: The Kotlin object is then serialized back into JSON format.
-3. Verification: The newly generated JSON is compared, character by character[^7], to the original
-   JSON to ensure complete fidelity.
+1. Serialization round-trip test:
+   - Deserialization: The JSON is parsed into its corresponding generated Kotlin resource class.
+   - Serialization: That Kotlin object is then converted back into JSON.
+   - Verification: The regenerated JSON is compared character by character[^7] with the original to confirm exact fidelity.
+2. Equality test:
+   - First instance: Deserialize the JSON into a Kotlin resource object.
+   - Second instance: Deserialize the same JSON into a separate Kotlin resource object.
+   - Verification: The two objects are structurally equal (using `==` operator).
 
 [^7]: There are several exceptions. The FHIR specification allows for some variability in data
 representation, which may lead to differences between the original and newly serialized JSON. For
diff --git a/fhir-codegen/gradle-plugin/src/main/kotlin/com/google/fhir/codegen/ModelTypeSpecGenerator.kt b/fhir-codegen/gradle-plugin/src/main/kotlin/com/google/fhir/codegen/ModelTypeSpecGenerator.kt
index c534e1160..18dada844 100644
--- a/fhir-codegen/gradle-plugin/src/main/kotlin/com/google/fhir/codegen/ModelTypeSpecGenerator.kt
+++ b/fhir-codegen/gradle-plugin/src/main/kotlin/com/google/fhir/codegen/ModelTypeSpecGenerator.kt
@@ -81,6 +81,11 @@ class ModelTypeSpecGenerator(private val valueSetMap: Map<String, ValueSet>) {
             // with '_'.
             if (structureDefinition.name == "Element") {
               addModifiers(KModifier.OPEN)
+              // Implement equals/hashCode for Element to compare properties (like data classes).
+              addEqualsAndHashCodeFunctions(
+                structureDefinition.name,
+                structureDefinition.rootElements,
+              )
             } else {
               addModifiers(KModifier.SEALED)
             }
@@ -92,6 +97,12 @@ class ModelTypeSpecGenerator(private val valueSetMap: Map<String, ValueSet>) {
             // since they need to be subclassed. E.g. Uri can be extended by Url, and Quantity can
             // be extended by Duration.
             addModifiers(KModifier.OPEN)
+            // Implement equals/hashCode for open classes (to perform property-based comparison,
+            // like data classes).
+            addEqualsAndHashCodeFunctions(
+              structureDefinition.name,
+              structureDefinition.rootElements,
+            )
           } else {
             addModifiers(KModifier.DATA)
           }
@@ -195,6 +206,55 @@ class ModelTypeSpecGenerator(private val valueSetMap: Map<String, ValueSet>) {
     return typeSpec
   }
 
+  private fun TypeSpec.Builder.addEqualsAndHashCodeFunctions(
+    name: String,
+    elements: List<Element>,
+  ) {
+    if (elements.isEmpty()) return
+    val equalsFunSpec =
+      FunSpec.builder("equals")
+        .addModifiers(KModifier.OVERRIDE)
+        .addParameter("other", Any::class.asTypeName().copy(nullable = true))
+        .returns(Boolean::class)
+        .addCode(
+          """
+            if (this === other) return true
+            if (other !is ${name.capitalized()}) return false
+        """
+            .trimIndent()
+        )
+        .addCode(
+          elements.joinToString(separator = "\n", prefix = "\n", postfix = "\n") {
+            "if( ${it.getElementName()} != other.${it.getElementName()}) return false"
+          }
+        )
+        .addCode("return true")
+        .build()
+
+    this.addFunction(equalsFunSpec)
+
+    val hashCodeFunSpec =
+      FunSpec.builder("hashCode")
+        .addModifiers(KModifier.OVERRIDE)
+        .returns(Int::class)
+        .addCode(
+          "// Using 31 improves hash distribution and reduces collisions in hash-based collections\n"
+        )
+        .addCode("var result = ${elements.first().getElementName()}?.hashCode() ?: 0")
+        .addCode(
+          elements.subList(1, elements.size).joinToString(
+            separator = "\n",
+            prefix = "\n",
+            postfix = "\n",
+          ) {
+            "result = 31 * result + (${it.getElementName()}?.hashCode() ?: 0)"
+          }
+        )
+        .addCode("return result")
+        .build()
+    this.addFunction(hashCodeFunSpec)
+  }
+
   /** Adds a nested class for each BackboneElement in the [StructureDefinition]. */
   private fun TypeSpec.Builder.addBackboneElement(
     path: String,
diff --git a/fhir-codegen/gradle-plugin/src/main/kotlin/com/google/fhir/codegen/primitives/FhirDateFileSpecGenerator.kt b/fhir-codegen/gradle-plugin/src/main/kotlin/com/google/fhir/codegen/primitives/FhirDateFileSpecGenerator.kt
index e575c310d..1880c7197 100644
--- a/fhir-codegen/gradle-plugin/src/main/kotlin/com/google/fhir/codegen/primitives/FhirDateFileSpecGenerator.kt
+++ b/fhir-codegen/gradle-plugin/src/main/kotlin/com/google/fhir/codegen/primitives/FhirDateFileSpecGenerator.kt
@@ -64,6 +64,7 @@ object FhirDateFileSpecGenerator {
             )
             addType(
               TypeSpec.classBuilder("YearMonth")
+                .addModifiers(KModifier.DATA)
                 .addSuperinterface(sealedInterfaceClassName)
                 .primaryConstructor(
                   FunSpec.constructorBuilder()
@@ -84,6 +85,7 @@ object FhirDateFileSpecGenerator {
             )
             addType(
               TypeSpec.classBuilder("Date")
+                .addModifiers(KModifier.DATA)
                 .addSuperinterface(sealedInterfaceClassName)
                 .primaryConstructor(
                   FunSpec.constructorBuilder().addParameter("date", LocalDate::class).build()
diff --git a/fhir-codegen/gradle-plugin/src/main/kotlin/com/google/fhir/codegen/primitives/FhirDateTimeFileSpecGenerator.kt b/fhir-codegen/gradle-plugin/src/main/kotlin/com/google/fhir/codegen/primitives/FhirDateTimeFileSpecGenerator.kt
index e6fb83e74..3885b996a 100644
--- a/fhir-codegen/gradle-plugin/src/main/kotlin/com/google/fhir/codegen/primitives/FhirDateTimeFileSpecGenerator.kt
+++ b/fhir-codegen/gradle-plugin/src/main/kotlin/com/google/fhir/codegen/primitives/FhirDateTimeFileSpecGenerator.kt
@@ -69,6 +69,7 @@ object FhirDateTimeFileSpecGenerator {
             )
             addType(
               TypeSpec.classBuilder("YearMonth")
+                .addModifiers(KModifier.DATA)
                 .addSuperinterface(sealedInterfaceClassName)
                 .primaryConstructor(
                   FunSpec.constructorBuilder()
@@ -89,6 +90,7 @@ object FhirDateTimeFileSpecGenerator {
             )
             addType(
               TypeSpec.classBuilder("Date")
+                .addModifiers(KModifier.DATA)
                 .addSuperinterface(sealedInterfaceClassName)
                 .primaryConstructor(
                   FunSpec.constructorBuilder().addParameter("date", LocalDate::class).build()
@@ -107,6 +109,7 @@ object FhirDateTimeFileSpecGenerator {
             )
             addType(
               TypeSpec.classBuilder("DateTime")
+                .addModifiers(KModifier.DATA)
                 .addSuperinterface(sealedInterfaceClassName)
                 .primaryConstructor(
                   FunSpec.constructorBuilder()
diff --git a/fhir-model/build.gradle.kts b/fhir-model/build.gradle.kts
index f5941d40f..478950188 100644
--- a/fhir-model/build.gradle.kts
+++ b/fhir-model/build.gradle.kts
@@ -134,7 +134,11 @@ kotlin {
             }
         }
         val jvmMain by getting
-        val jvmTest by getting
+        val jvmTest by getting {
+            dependencies {
+                implementation("org.jetbrains.kotlin:kotlin-reflect")
+            }
+        }
         val jsMain by getting
         val jsTest by getting
     }
diff --git a/fhir-model/src/androidInstrumentedTest/kotlin/com/google/fhir/model/SerializationRoundTripTest.android.kt b/fhir-model/src/androidInstrumentedTest/kotlin/com/google/fhir/model/TestLoader.android.kt
similarity index 100%
rename from fhir-model/src/androidInstrumentedTest/kotlin/com/google/fhir/model/SerializationRoundTripTest.android.kt
rename to fhir-model/src/androidInstrumentedTest/kotlin/com/google/fhir/model/TestLoader.android.kt
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/Element.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/Element.kt
index c39ab3857..3a49bd23a 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/Element.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/Element.kt
@@ -18,6 +18,9 @@
 
 package com.google.fhir.model.r4
 
+import kotlin.Any
+import kotlin.Boolean
+import kotlin.Int
 import kotlin.String
 import kotlin.Suppress
 import kotlin.collections.MutableList
@@ -44,4 +47,19 @@ public open class Element(
    * simplicity for everyone.
    */
   public open var extension: MutableList<Extension> = mutableListOf(),
-)
+) {
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is Element) return false
+    if (id != other.id) return false
+    if (extension != other.extension) return false
+    return true
+  }
+
+  override fun hashCode(): Int {
+    // Using 31 improves hash distribution and reduces collisions in hash-based collections
+    var result = id?.hashCode() ?: 0
+    result = 31 * result + (extension?.hashCode() ?: 0)
+    return result
+  }
+}
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/FhirDate.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/FhirDate.kt
index da25c158a..ea1803db3 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/FhirDate.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/FhirDate.kt
@@ -30,11 +30,11 @@ public sealed interface FhirDate {
     override fun toString(): String = value.toString()
   }
 
-  public class YearMonth(public val year: Int, public val month: Int) : FhirDate {
+  public data class YearMonth(public val year: Int, public val month: Int) : FhirDate {
     override fun toString(): String = "$year-${month.toString().padStart(2,'0')}"
   }
 
-  public class Date(public val date: LocalDate) : FhirDate {
+  public data class Date(public val date: LocalDate) : FhirDate {
     override fun toString(): String = date.toString()
   }
 
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/FhirDateTime.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/FhirDateTime.kt
index b4843a45c..ca268fe20 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/FhirDateTime.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/FhirDateTime.kt
@@ -33,15 +33,15 @@ public sealed interface FhirDateTime {
     override fun toString(): String = value.toString()
   }
 
-  public class YearMonth(public val year: Int, public val month: Int) : FhirDateTime {
+  public data class YearMonth(public val year: Int, public val month: Int) : FhirDateTime {
     override fun toString(): String = "$year-${month.toString().padStart(2,'0')}"
   }
 
-  public class Date(public val date: LocalDate) : FhirDateTime {
+  public data class Date(public val date: LocalDate) : FhirDateTime {
     override fun toString(): String = date.toString()
   }
 
-  public class DateTime(public val dateTime: LocalDateTime, public val utcOffset: UtcOffset) :
+  public data class DateTime(public val dateTime: LocalDateTime, public val utcOffset: UtcOffset) :
     FhirDateTime {
     override fun toString(): String =
       dateTime.format(LocalDateTime.Formats.ISO) + utcOffset.toString()
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/Integer.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/Integer.kt
index eed3757b9..c8408c8c7 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/Integer.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/Integer.kt
@@ -18,6 +18,8 @@
 
 package com.google.fhir.model.r4
 
+import kotlin.Any
+import kotlin.Boolean
 import kotlin.Int
 import kotlin.String
 import kotlin.Suppress
@@ -43,6 +45,23 @@ public open class Integer(
   /** The actual value */
   public open var `value`: Int? = null,
 ) : Element(id, extension) {
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is Integer) return false
+    if (id != other.id) return false
+    if (extension != other.extension) return false
+    if (value != other.value) return false
+    return true
+  }
+
+  override fun hashCode(): Int {
+    // Using 31 improves hash distribution and reduces collisions in hash-based collections
+    var result = id?.hashCode() ?: 0
+    result = 31 * result + (extension?.hashCode() ?: 0)
+    result = 31 * result + (value?.hashCode() ?: 0)
+    return result
+  }
+
   public open fun toElement(): Element? {
     if (id != null || extension.isNotEmpty()) {
       return Element(id, extension)
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/Quantity.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/Quantity.kt
index b3ac6dd85..275f21a83 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/Quantity.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/Quantity.kt
@@ -19,6 +19,9 @@
 package com.google.fhir.model.r4
 
 import com.google.fhir.model.r4.serializers.QuantitySerializer
+import kotlin.Any
+import kotlin.Boolean
+import kotlin.Int
 import kotlin.Suppress
 import kotlin.collections.MutableList
 import kotlinx.serialization.Serializable
@@ -74,6 +77,31 @@ public open class Quantity(
    */
   public open var code: Code? = null,
 ) : Element() {
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is Quantity) return false
+    if (id != other.id) return false
+    if (extension != other.extension) return false
+    if (value != other.value) return false
+    if (comparator != other.comparator) return false
+    if (unit != other.unit) return false
+    if (system != other.system) return false
+    if (code != other.code) return false
+    return true
+  }
+
+  override fun hashCode(): Int {
+    // Using 31 improves hash distribution and reduces collisions in hash-based collections
+    var result = id?.hashCode() ?: 0
+    result = 31 * result + (extension?.hashCode() ?: 0)
+    result = 31 * result + (value?.hashCode() ?: 0)
+    result = 31 * result + (comparator?.hashCode() ?: 0)
+    result = 31 * result + (unit?.hashCode() ?: 0)
+    result = 31 * result + (system?.hashCode() ?: 0)
+    result = 31 * result + (code?.hashCode() ?: 0)
+    return result
+  }
+
   /** How the Quantity should be understood and represented. */
   public enum class QuantityComparator(
     private val code: kotlin.String,
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/String.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/String.kt
index cdc8d8ab8..2d058cb8e 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/String.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/String.kt
@@ -18,6 +18,9 @@
 
 package com.google.fhir.model.r4
 
+import kotlin.Any
+import kotlin.Boolean
+import kotlin.Int
 import kotlin.Suppress
 import kotlin.collections.MutableList
 
@@ -41,6 +44,23 @@ public open class String(
   /** The actual value */
   public open var `value`: kotlin.String? = null,
 ) : Element(id, extension) {
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is String) return false
+    if (id != other.id) return false
+    if (extension != other.extension) return false
+    if (value != other.value) return false
+    return true
+  }
+
+  override fun hashCode(): Int {
+    // Using 31 improves hash distribution and reduces collisions in hash-based collections
+    var result = id?.hashCode() ?: 0
+    result = 31 * result + (extension?.hashCode() ?: 0)
+    result = 31 * result + (value?.hashCode() ?: 0)
+    return result
+  }
+
   public open fun toElement(): Element? {
     if (id != null || extension.isNotEmpty()) {
       return Element(id, extension)
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/Uri.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/Uri.kt
index 876594c5c..d5673fda4 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/Uri.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4/Uri.kt
@@ -18,6 +18,9 @@
 
 package com.google.fhir.model.r4
 
+import kotlin.Any
+import kotlin.Boolean
+import kotlin.Int
 import kotlin.String
 import kotlin.Suppress
 import kotlin.collections.MutableList
@@ -44,6 +47,23 @@ public open class Uri(
   /** The actual value */
   public open var `value`: String? = null,
 ) : Element(id, extension) {
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is Uri) return false
+    if (id != other.id) return false
+    if (extension != other.extension) return false
+    if (value != other.value) return false
+    return true
+  }
+
+  override fun hashCode(): Int {
+    // Using 31 improves hash distribution and reduces collisions in hash-based collections
+    var result = id?.hashCode() ?: 0
+    result = 31 * result + (extension?.hashCode() ?: 0)
+    result = 31 * result + (value?.hashCode() ?: 0)
+    return result
+  }
+
   public open fun toElement(): Element? {
     if (id != null || extension.isNotEmpty()) {
       return Element(id, extension)
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/Element.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/Element.kt
index f53132f64..c07909a9a 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/Element.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/Element.kt
@@ -18,6 +18,9 @@
 
 package com.google.fhir.model.r4b
 
+import kotlin.Any
+import kotlin.Boolean
+import kotlin.Int
 import kotlin.String
 import kotlin.Suppress
 import kotlin.collections.MutableList
@@ -44,4 +47,19 @@ public open class Element(
    * simplicity for everyone.
    */
   public open var extension: MutableList<Extension> = mutableListOf(),
-)
+) {
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is Element) return false
+    if (id != other.id) return false
+    if (extension != other.extension) return false
+    return true
+  }
+
+  override fun hashCode(): Int {
+    // Using 31 improves hash distribution and reduces collisions in hash-based collections
+    var result = id?.hashCode() ?: 0
+    result = 31 * result + (extension?.hashCode() ?: 0)
+    return result
+  }
+}
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/FhirDate.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/FhirDate.kt
index a85e8ac8e..6d54c6cde 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/FhirDate.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/FhirDate.kt
@@ -30,11 +30,11 @@ public sealed interface FhirDate {
     override fun toString(): String = value.toString()
   }
 
-  public class YearMonth(public val year: Int, public val month: Int) : FhirDate {
+  public data class YearMonth(public val year: Int, public val month: Int) : FhirDate {
     override fun toString(): String = "$year-${month.toString().padStart(2,'0')}"
   }
 
-  public class Date(public val date: LocalDate) : FhirDate {
+  public data class Date(public val date: LocalDate) : FhirDate {
     override fun toString(): String = date.toString()
   }
 
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/FhirDateTime.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/FhirDateTime.kt
index 44f86990c..ecde52de1 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/FhirDateTime.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/FhirDateTime.kt
@@ -33,15 +33,15 @@ public sealed interface FhirDateTime {
     override fun toString(): String = value.toString()
   }
 
-  public class YearMonth(public val year: Int, public val month: Int) : FhirDateTime {
+  public data class YearMonth(public val year: Int, public val month: Int) : FhirDateTime {
     override fun toString(): String = "$year-${month.toString().padStart(2,'0')}"
   }
 
-  public class Date(public val date: LocalDate) : FhirDateTime {
+  public data class Date(public val date: LocalDate) : FhirDateTime {
     override fun toString(): String = date.toString()
   }
 
-  public class DateTime(public val dateTime: LocalDateTime, public val utcOffset: UtcOffset) :
+  public data class DateTime(public val dateTime: LocalDateTime, public val utcOffset: UtcOffset) :
     FhirDateTime {
     override fun toString(): String =
       dateTime.format(LocalDateTime.Formats.ISO) + utcOffset.toString()
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/Integer.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/Integer.kt
index 2a5ee4d5a..86f761e61 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/Integer.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/Integer.kt
@@ -18,6 +18,8 @@
 
 package com.google.fhir.model.r4b
 
+import kotlin.Any
+import kotlin.Boolean
 import kotlin.Int
 import kotlin.String
 import kotlin.Suppress
@@ -43,6 +45,23 @@ public open class Integer(
   /** The actual value */
   public open var `value`: Int? = null,
 ) : Element(id, extension) {
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is Integer) return false
+    if (id != other.id) return false
+    if (extension != other.extension) return false
+    if (value != other.value) return false
+    return true
+  }
+
+  override fun hashCode(): Int {
+    // Using 31 improves hash distribution and reduces collisions in hash-based collections
+    var result = id?.hashCode() ?: 0
+    result = 31 * result + (extension?.hashCode() ?: 0)
+    result = 31 * result + (value?.hashCode() ?: 0)
+    return result
+  }
+
   public open fun toElement(): Element? {
     if (id != null || extension.isNotEmpty()) {
       return Element(id, extension)
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/Quantity.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/Quantity.kt
index b4ee3e208..a23a1dc41 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/Quantity.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/Quantity.kt
@@ -19,6 +19,9 @@
 package com.google.fhir.model.r4b
 
 import com.google.fhir.model.r4b.serializers.QuantitySerializer
+import kotlin.Any
+import kotlin.Boolean
+import kotlin.Int
 import kotlin.Suppress
 import kotlin.collections.MutableList
 import kotlinx.serialization.Serializable
@@ -74,6 +77,31 @@ public open class Quantity(
    */
   public open var code: Code? = null,
 ) : Element() {
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is Quantity) return false
+    if (id != other.id) return false
+    if (extension != other.extension) return false
+    if (value != other.value) return false
+    if (comparator != other.comparator) return false
+    if (unit != other.unit) return false
+    if (system != other.system) return false
+    if (code != other.code) return false
+    return true
+  }
+
+  override fun hashCode(): Int {
+    // Using 31 improves hash distribution and reduces collisions in hash-based collections
+    var result = id?.hashCode() ?: 0
+    result = 31 * result + (extension?.hashCode() ?: 0)
+    result = 31 * result + (value?.hashCode() ?: 0)
+    result = 31 * result + (comparator?.hashCode() ?: 0)
+    result = 31 * result + (unit?.hashCode() ?: 0)
+    result = 31 * result + (system?.hashCode() ?: 0)
+    result = 31 * result + (code?.hashCode() ?: 0)
+    return result
+  }
+
   /** How the Quantity should be understood and represented. */
   public enum class QuantityComparator(
     private val code: kotlin.String,
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/String.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/String.kt
index a12a4eb98..20685f85c 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/String.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/String.kt
@@ -18,6 +18,9 @@
 
 package com.google.fhir.model.r4b
 
+import kotlin.Any
+import kotlin.Boolean
+import kotlin.Int
 import kotlin.Suppress
 import kotlin.collections.MutableList
 
@@ -41,6 +44,23 @@ public open class String(
   /** The actual value */
   public open var `value`: kotlin.String? = null,
 ) : Element(id, extension) {
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is String) return false
+    if (id != other.id) return false
+    if (extension != other.extension) return false
+    if (value != other.value) return false
+    return true
+  }
+
+  override fun hashCode(): Int {
+    // Using 31 improves hash distribution and reduces collisions in hash-based collections
+    var result = id?.hashCode() ?: 0
+    result = 31 * result + (extension?.hashCode() ?: 0)
+    result = 31 * result + (value?.hashCode() ?: 0)
+    return result
+  }
+
   public open fun toElement(): Element? {
     if (id != null || extension.isNotEmpty()) {
       return Element(id, extension)
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/Uri.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/Uri.kt
index 807852057..425f58471 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/Uri.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r4b/Uri.kt
@@ -18,6 +18,9 @@
 
 package com.google.fhir.model.r4b
 
+import kotlin.Any
+import kotlin.Boolean
+import kotlin.Int
 import kotlin.String
 import kotlin.Suppress
 import kotlin.collections.MutableList
@@ -44,6 +47,23 @@ public open class Uri(
   /** The actual value */
   public open var `value`: String? = null,
 ) : Element(id, extension) {
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is Uri) return false
+    if (id != other.id) return false
+    if (extension != other.extension) return false
+    if (value != other.value) return false
+    return true
+  }
+
+  override fun hashCode(): Int {
+    // Using 31 improves hash distribution and reduces collisions in hash-based collections
+    var result = id?.hashCode() ?: 0
+    result = 31 * result + (extension?.hashCode() ?: 0)
+    result = 31 * result + (value?.hashCode() ?: 0)
+    return result
+  }
+
   public open fun toElement(): Element? {
     if (id != null || extension.isNotEmpty()) {
       return Element(id, extension)
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/Element.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/Element.kt
index 75763b26a..37ac0f4d3 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/Element.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/Element.kt
@@ -18,6 +18,9 @@
 
 package com.google.fhir.model.r5
 
+import kotlin.Any
+import kotlin.Boolean
+import kotlin.Int
 import kotlin.String
 import kotlin.Suppress
 import kotlin.collections.MutableList
@@ -44,4 +47,19 @@ public open class Element(
    * simplicity for everyone.
    */
   public open var extension: MutableList<Extension> = mutableListOf(),
-) : Base()
+) : Base() {
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is Element) return false
+    if (id != other.id) return false
+    if (extension != other.extension) return false
+    return true
+  }
+
+  override fun hashCode(): Int {
+    // Using 31 improves hash distribution and reduces collisions in hash-based collections
+    var result = id?.hashCode() ?: 0
+    result = 31 * result + (extension?.hashCode() ?: 0)
+    return result
+  }
+}
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/FhirDate.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/FhirDate.kt
index 289429c0e..aedf9a90f 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/FhirDate.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/FhirDate.kt
@@ -30,11 +30,11 @@ public sealed interface FhirDate {
     override fun toString(): String = value.toString()
   }
 
-  public class YearMonth(public val year: Int, public val month: Int) : FhirDate {
+  public data class YearMonth(public val year: Int, public val month: Int) : FhirDate {
     override fun toString(): String = "$year-${month.toString().padStart(2,'0')}"
   }
 
-  public class Date(public val date: LocalDate) : FhirDate {
+  public data class Date(public val date: LocalDate) : FhirDate {
     override fun toString(): String = date.toString()
   }
 
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/FhirDateTime.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/FhirDateTime.kt
index 9079eaffd..98247a437 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/FhirDateTime.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/FhirDateTime.kt
@@ -33,15 +33,15 @@ public sealed interface FhirDateTime {
     override fun toString(): String = value.toString()
   }
 
-  public class YearMonth(public val year: Int, public val month: Int) : FhirDateTime {
+  public data class YearMonth(public val year: Int, public val month: Int) : FhirDateTime {
     override fun toString(): String = "$year-${month.toString().padStart(2,'0')}"
   }
 
-  public class Date(public val date: LocalDate) : FhirDateTime {
+  public data class Date(public val date: LocalDate) : FhirDateTime {
     override fun toString(): String = date.toString()
   }
 
-  public class DateTime(public val dateTime: LocalDateTime, public val utcOffset: UtcOffset) :
+  public data class DateTime(public val dateTime: LocalDateTime, public val utcOffset: UtcOffset) :
     FhirDateTime {
     override fun toString(): String =
       dateTime.format(LocalDateTime.Formats.ISO) + utcOffset.toString()
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/Integer.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/Integer.kt
index cfdb2fa5b..7da548299 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/Integer.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/Integer.kt
@@ -18,6 +18,8 @@
 
 package com.google.fhir.model.r5
 
+import kotlin.Any
+import kotlin.Boolean
 import kotlin.Int
 import kotlin.String
 import kotlin.Suppress
@@ -43,6 +45,23 @@ public open class Integer(
   /** The actual value */
   public open var `value`: Int? = null,
 ) : PrimitiveType() {
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is Integer) return false
+    if (id != other.id) return false
+    if (extension != other.extension) return false
+    if (value != other.value) return false
+    return true
+  }
+
+  override fun hashCode(): Int {
+    // Using 31 improves hash distribution and reduces collisions in hash-based collections
+    var result = id?.hashCode() ?: 0
+    result = 31 * result + (extension?.hashCode() ?: 0)
+    result = 31 * result + (value?.hashCode() ?: 0)
+    return result
+  }
+
   public open fun toElement(): Element? {
     if (id != null || extension.isNotEmpty()) {
       return Element(id, extension)
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/Quantity.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/Quantity.kt
index d48c8a4b2..73a344ce4 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/Quantity.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/Quantity.kt
@@ -19,6 +19,9 @@
 package com.google.fhir.model.r5
 
 import com.google.fhir.model.r5.serializers.QuantitySerializer
+import kotlin.Any
+import kotlin.Boolean
+import kotlin.Int
 import kotlin.Suppress
 import kotlin.collections.MutableList
 import kotlinx.serialization.Serializable
@@ -74,6 +77,31 @@ public open class Quantity(
    */
   public open var code: Code? = null,
 ) : DataType() {
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is Quantity) return false
+    if (id != other.id) return false
+    if (extension != other.extension) return false
+    if (value != other.value) return false
+    if (comparator != other.comparator) return false
+    if (unit != other.unit) return false
+    if (system != other.system) return false
+    if (code != other.code) return false
+    return true
+  }
+
+  override fun hashCode(): Int {
+    // Using 31 improves hash distribution and reduces collisions in hash-based collections
+    var result = id?.hashCode() ?: 0
+    result = 31 * result + (extension?.hashCode() ?: 0)
+    result = 31 * result + (value?.hashCode() ?: 0)
+    result = 31 * result + (comparator?.hashCode() ?: 0)
+    result = 31 * result + (unit?.hashCode() ?: 0)
+    result = 31 * result + (system?.hashCode() ?: 0)
+    result = 31 * result + (code?.hashCode() ?: 0)
+    return result
+  }
+
   /** How the Quantity should be understood and represented. */
   public enum class QuantityComparator(
     private val code: kotlin.String,
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/String.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/String.kt
index f0017db54..f9e8e3dea 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/String.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/String.kt
@@ -18,6 +18,9 @@
 
 package com.google.fhir.model.r5
 
+import kotlin.Any
+import kotlin.Boolean
+import kotlin.Int
 import kotlin.Suppress
 import kotlin.collections.MutableList
 
@@ -41,6 +44,23 @@ public open class String(
   /** The actual value */
   public open var `value`: kotlin.String? = null,
 ) : PrimitiveType() {
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is String) return false
+    if (id != other.id) return false
+    if (extension != other.extension) return false
+    if (value != other.value) return false
+    return true
+  }
+
+  override fun hashCode(): Int {
+    // Using 31 improves hash distribution and reduces collisions in hash-based collections
+    var result = id?.hashCode() ?: 0
+    result = 31 * result + (extension?.hashCode() ?: 0)
+    result = 31 * result + (value?.hashCode() ?: 0)
+    return result
+  }
+
   public open fun toElement(): Element? {
     if (id != null || extension.isNotEmpty()) {
       return Element(id, extension)
diff --git a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/Uri.kt b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/Uri.kt
index 5df1dcb18..c62206c65 100644
--- a/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/Uri.kt
+++ b/fhir-model/src/commonMain/kotlin/com/google/fhir/model/r5/Uri.kt
@@ -18,6 +18,9 @@
 
 package com.google.fhir.model.r5
 
+import kotlin.Any
+import kotlin.Boolean
+import kotlin.Int
 import kotlin.String
 import kotlin.Suppress
 import kotlin.collections.MutableList
@@ -42,6 +45,23 @@ public open class Uri(
   /** The actual value */
   public open var `value`: String? = null,
 ) : PrimitiveType() {
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is Uri) return false
+    if (id != other.id) return false
+    if (extension != other.extension) return false
+    if (value != other.value) return false
+    return true
+  }
+
+  override fun hashCode(): Int {
+    // Using 31 improves hash distribution and reduces collisions in hash-based collections
+    var result = id?.hashCode() ?: 0
+    result = 31 * result + (extension?.hashCode() ?: 0)
+    result = 31 * result + (value?.hashCode() ?: 0)
+    return result
+  }
+
   public open fun toElement(): Element? {
     if (id != null || extension.isNotEmpty()) {
       return Element(id, extension)
diff --git a/fhir-model/src/commonTest/kotlin/com/google/fhir/model/EqualityTest.kt b/fhir-model/src/commonTest/kotlin/com/google/fhir/model/EqualityTest.kt
new file mode 100644
index 000000000..0d58d05cb
--- /dev/null
+++ b/fhir-model/src/commonTest/kotlin/com/google/fhir/model/EqualityTest.kt
@@ -0,0 +1,96 @@
+/*
+ * Copyright 2025 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.fhir.model
+
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class EqualityTest {
+
+  @Test
+  fun shouldMatchResourcesWithSimilarPropertiesOnComparisonInR4() {
+    loadR4Examples(
+        fileNameFilter = {
+          return@loadR4Examples (filterFileName(it) && !exclusionListR4.contains(it))
+        }
+      )
+      .forEach { exampleJson ->
+        val firstResource = jsonR4.decodeFromString<com.google.fhir.model.r4.Resource>(exampleJson)
+        val secondResource = jsonR4.decodeFromString<com.google.fhir.model.r4.Resource>(exampleJson)
+        assertEquals(firstResource, secondResource)
+      }
+  }
+
+  @Test
+  fun shouldMatchResourcesWithSimilarPropertiesOnComparisonInR4B() {
+    loadR4BExamples(
+        fileNameFilter = {
+          return@loadR4BExamples (filterFileName(it) && !exclusionListR4B.contains(it))
+        }
+      )
+      .forEach { exampleJson ->
+        val firstResource: com.google.fhir.model.r4b.Resource =
+          jsonR4B.decodeFromString<com.google.fhir.model.r4b.Resource>(exampleJson)
+        val secondResource: com.google.fhir.model.r4b.Resource =
+          jsonR4B.decodeFromString<com.google.fhir.model.r4b.Resource>(exampleJson)
+        assertEquals(firstResource, secondResource)
+      }
+  }
+
+  @Test
+  fun shouldMatchResourcesWithSimilarPropertiesOnComparisonInR5() {
+    loadR5Examples(
+        fileNameFilter = {
+          return@loadR5Examples (filterFileName(it) && !exclusionListR5.contains(it))
+        }
+      )
+      .forEach { exampleJson ->
+        val firstResource: com.google.fhir.model.r5.Resource =
+          jsonR5.decodeFromString<com.google.fhir.model.r5.Resource>(exampleJson)
+        val secondResource: com.google.fhir.model.r5.Resource =
+          jsonR5.decodeFromString<com.google.fhir.model.r5.Resource>(exampleJson)
+        assertEquals(firstResource, secondResource)
+      }
+  }
+
+  companion object {
+
+    private val exclusionListR4 =
+      listOf(
+        // Invalid resources
+        "ActivityDefinition-administer-zika-virus-exposure-assessment.json",
+        "ImplementationGuide-fhir.json",
+        "Questionnaire-qs1.json",
+        "ig-r4.json",
+      )
+
+    private val exclusionListR4B =
+      listOf(
+        // Invalid resource
+        "Bundle-valuesets.json",
+        "CodeSystem-catalogType.json",
+        "ValueSet-catalogType.json",
+        "ActivityDefinition-administer-zika-virus-exposure-assessment.json",
+      )
+
+    private val exclusionListR5 =
+      listOf(
+        // Unknown code 'text/CQL' for enum ExpressionLanguage; codes are case-sensitive
+        "ChargeItemDefinition-ebm.json"
+      )
+  }
+}
diff --git a/fhir-model/src/commonTest/kotlin/com/google/fhir/model/SerializationRoundTripTest.kt b/fhir-model/src/commonTest/kotlin/com/google/fhir/model/SerializationRoundTripTest.kt
index d096e375b..40475a567 100644
--- a/fhir-model/src/commonTest/kotlin/com/google/fhir/model/SerializationRoundTripTest.kt
+++ b/fhir-model/src/commonTest/kotlin/com/google/fhir/model/SerializationRoundTripTest.kt
@@ -16,81 +16,11 @@
 
 package com.google.fhir.model
 
-import com.google.fhir.model.r4.configureR4
-import com.google.fhir.model.r4b.configureR4b
-import com.google.fhir.model.r5.configureR5
 import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlinx.serialization.json.Json
 import kotlinx.serialization.json.jsonObject
 
-const val r4ExamplePackage = "hl7.fhir.r4.examples/package/"
-const val r4bExamplePackage = "hl7.fhir.r4b.examples/package/"
-const val r5ExamplePackage = "hl7.fhir.r5.examples/package/"
-
-val trailingZeroRegex = "\\.0+".toRegex()
-
-val exclusionListR4 =
-  listOf(
-    // Hanging for no reason
-    "Bundle-terminologies.json",
-    "CodeSystem-v2-0003.json",
-    "Bundle-valueset-expansions.json",
-
-    // Java heap space
-    "Bundle-resources.json",
-    "Bundle-dataelements.json",
-    "CodeSystem-v3-ManagedParticipationStatus.json",
-
-    // Instant with trailing 0s
-    "ValueSet-v3-hl7PublishingSubSection.json",
-
-    // Scientific notation
-    "Observation-decimal.json",
-
-    // Invalid resources
-    "ActivityDefinition-administer-zika-virus-exposure-assessment.json",
-    "ImplementationGuide-fhir.json",
-    "Questionnaire-qs1.json",
-    "ig-r4.json",
-  )
-
-val exclusionListR4B =
-  listOf(
-    // Java heap space
-    "Bundle-resources.json",
-
-    // Scientific notation
-    "Observation-decimal.json",
-
-    // Invalid resource
-    "Bundle-valuesets.json",
-    "CodeSystem-catalogType.json",
-    "ValueSet-catalogType.json",
-
-    // Invalid resources
-    "ActivityDefinition-administer-zika-virus-exposure-assessment.json",
-  )
-
-val exclusionListR5 =
-  listOf(
-    // Hanging
-    "Bundle-searchParams.json",
-
-    // Java heap space
-    "Bundle-resources.json",
-
-    // Trailing 0 in milliseconds
-    "ArtifactAssessment-example-certainty-rating.json",
-    "Citation-citation-example-research-doi.json",
-
-    // Scientific notation
-    "Observation-decimal.json",
-
-    // Unknown code 'text/CQL' for enum ExpressionLanguage; codes are case-sensitive
-    "ChargeItemDefinition-ebm.json",
-  )
-
 /**
  * This test verifies the generated code can be used to deserialize published FHIR examples and
  * serialize them back to the original JSON.
@@ -105,8 +35,7 @@ class SerializationRoundTripTest {
       )
       .forEach {
         val exampleJson = prettyPrintJson(it)
-        val domainResource: com.google.fhir.model.r4.Resource =
-          jsonR4.decodeFromString<com.google.fhir.model.r4.Resource>(exampleJson)
+        val domainResource = jsonR4.decodeFromString<com.google.fhir.model.r4.Resource>(exampleJson)
         val reserializedString = jsonR4.encodeToString(domainResource)
         assertEqualsIgnoringZeros(exampleJson, reserializedString)
       }
@@ -145,35 +74,70 @@ class SerializationRoundTripTest {
   }
 
   companion object {
-    private val jsonR4 = Json {
-      prettyPrint = true
-      configureR4()
-    }
+    private val prettyPrintJson = Json { prettyPrint = true }
 
-    private val jsonR4B = Json {
-      prettyPrint = true
-      configureR4b()
-    }
+    private val trailingZeroRegex = "\\.0+".toRegex()
 
-    private val jsonR5 = Json {
-      prettyPrint = true
-      configureR5()
-    }
+    private val exclusionListR4 =
+      listOf(
+        // Hanging for no reason
+        "Bundle-terminologies.json",
+        "CodeSystem-v2-0003.json",
+        "Bundle-valueset-expansions.json",
 
-    private val prettyPrintJson = Json { prettyPrint = true }
+        // Java heap space
+        "Bundle-resources.json",
+        "Bundle-dataelements.json",
+        "CodeSystem-v3-ManagedParticipationStatus.json",
 
-    fun filterFileName(name: String): Boolean {
-      return name.endsWith(".json") &&
-        !name.startsWith('.') // filter out `.index.json` file
-        &&
-        name != "package.json"
-    }
+        // Instant with trailing 0s
+        "ValueSet-v3-hl7PublishingSubSection.json",
 
-    private fun prettyPrintJson(jsonString: String): String {
-      val jsonElement =
-        prettyPrintJson.parseToJsonElement(jsonString) // Parse the string to a JsonElement
-      return prettyPrintJson.encodeToString(jsonElement) // Re-encode with pretty printing
-    }
+        // Scientific notation
+        "Observation-decimal.json",
+
+        // Invalid resources
+        "ActivityDefinition-administer-zika-virus-exposure-assessment.json",
+        "ImplementationGuide-fhir.json",
+        "Questionnaire-qs1.json",
+        "ig-r4.json",
+      )
+
+    private val exclusionListR4B =
+      listOf(
+        // Java heap space
+        "Bundle-resources.json",
+
+        // Scientific notation
+        "Observation-decimal.json",
+
+        // Invalid resource
+        "Bundle-valuesets.json",
+        "CodeSystem-catalogType.json",
+        "ValueSet-catalogType.json",
+
+        // Invalid resources
+        "ActivityDefinition-administer-zika-virus-exposure-assessment.json",
+      )
+
+    private val exclusionListR5 =
+      listOf(
+        // Hanging
+        "Bundle-searchParams.json",
+
+        // Java heap space
+        "Bundle-resources.json",
+
+        // Trailing 0 in milliseconds
+        "ArtifactAssessment-example-certainty-rating.json",
+        "Citation-citation-example-research-doi.json",
+
+        // Scientific notation
+        "Observation-decimal.json",
+
+        // Unknown code 'text/CQL' for enum ExpressionLanguage; codes are case-sensitive
+        "ChargeItemDefinition-ebm.json",
+      )
 
     private fun assertEqualsIgnoringZeros(exampleJson: String, reserializedString: String) {
       val expected =
@@ -191,11 +155,11 @@ class SerializationRoundTripTest {
     }
 
     private fun String.removeZerosAfterDecimalPoint(): String = replace(trailingZeroRegex, "")
+
+    private fun prettyPrintJson(jsonString: String): String {
+      val jsonElement =
+        prettyPrintJson.parseToJsonElement(jsonString) // Parse the string to a JsonElement
+      return prettyPrintJson.encodeToString(jsonElement) // Re-encode with pretty printing
+    }
   }
 }
-
-expect fun loadR4Examples(fileNameFilter: (String) -> Boolean): Sequence<String>
-
-expect fun loadR4BExamples(fileNameFilter: (String) -> Boolean): Sequence<String>
-
-expect fun loadR5Examples(fileNameFilter: (String) -> Boolean): Sequence<String>
diff --git a/fhir-model/src/commonTest/kotlin/com/google/fhir/model/TestJson.kt b/fhir-model/src/commonTest/kotlin/com/google/fhir/model/TestJson.kt
new file mode 100644
index 000000000..1d7580774
--- /dev/null
+++ b/fhir-model/src/commonTest/kotlin/com/google/fhir/model/TestJson.kt
@@ -0,0 +1,37 @@
+/*
+ * Copyright 2025 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.fhir.model
+
+import com.google.fhir.model.r4.configureR4
+import com.google.fhir.model.r4b.configureR4b
+import com.google.fhir.model.r5.configureR5
+import kotlinx.serialization.json.Json
+
+val jsonR4 = Json {
+  prettyPrint = true
+  configureR4()
+}
+
+val jsonR4B = Json {
+  prettyPrint = true
+  configureR4b()
+}
+
+val jsonR5 = Json {
+  prettyPrint = true
+  configureR5()
+}
diff --git a/fhir-model/src/commonTest/kotlin/com/google/fhir/model/TestLoader.kt b/fhir-model/src/commonTest/kotlin/com/google/fhir/model/TestLoader.kt
new file mode 100644
index 000000000..d92c296e0
--- /dev/null
+++ b/fhir-model/src/commonTest/kotlin/com/google/fhir/model/TestLoader.kt
@@ -0,0 +1,34 @@
+/*
+ * Copyright 2025 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.fhir.model
+
+const val r4ExamplePackage = "hl7.fhir.r4.examples/package/"
+const val r4bExamplePackage = "hl7.fhir.r4b.examples/package/"
+const val r5ExamplePackage = "hl7.fhir.r5.examples/package/"
+
+fun filterFileName(name: String): Boolean {
+  return name.endsWith(".json") &&
+    !name.startsWith('.') // filter out `.index.json` file
+    &&
+    name != "package.json"
+}
+
+expect fun loadR4Examples(fileNameFilter: (String) -> Boolean): Sequence<String>
+
+expect fun loadR4BExamples(fileNameFilter: (String) -> Boolean): Sequence<String>
+
+expect fun loadR5Examples(fileNameFilter: (String) -> Boolean): Sequence<String>
diff --git a/fhir-model/src/jvmTest/kotlin/com/google/fhir/model/SerializationRoundTripTest.jvm.kt b/fhir-model/src/jvmTest/kotlin/com/google/fhir/model/TestLoader.jvm.kt
similarity index 100%
rename from fhir-model/src/jvmTest/kotlin/com/google/fhir/model/SerializationRoundTripTest.jvm.kt
rename to fhir-model/src/jvmTest/kotlin/com/google/fhir/model/TestLoader.jvm.kt
index 1253c0d83..df473eef4 100644
--- a/fhir-model/src/jvmTest/kotlin/com/google/fhir/model/SerializationRoundTripTest.jvm.kt
+++ b/fhir-model/src/jvmTest/kotlin/com/google/fhir/model/TestLoader.jvm.kt
@@ -18,17 +18,6 @@ package com.google.fhir.model
 
 import java.io.File
 
-private fun loadExamplesFromFileSystem(
-  directoryName: String,
-  fileNameFilter: (String) -> Boolean,
-): Sequence<String> {
-  return File("${System.getProperty("projectRootDir")}/third_party/${directoryName}")
-    .listFiles()!!
-    .asSequence()
-    .filter { fileNameFilter(it.name) }
-    .map { it.readText() }
-}
-
 actual fun loadR4Examples(fileNameFilter: (String) -> Boolean): Sequence<String> {
   return loadExamplesFromFileSystem(r4ExamplePackage, fileNameFilter)
 }
@@ -40,3 +29,14 @@ actual fun loadR4BExamples(fileNameFilter: (String) -> Boolean): Sequence<String
 actual fun loadR5Examples(fileNameFilter: (String) -> Boolean): Sequence<String> {
   return loadExamplesFromFileSystem(r5ExamplePackage, fileNameFilter)
 }
+
+private fun loadExamplesFromFileSystem(
+  directoryName: String,
+  fileNameFilter: (String) -> Boolean,
+): Sequence<String> {
+  return File("${System.getProperty("projectRootDir")}/third_party/${directoryName}")
+    .listFiles()!!
+    .asSequence()
+    .filter { fileNameFilter(it.name) }
+    .map { it.readText() }
+}