diff --git a/README.md b/README.md
index 6c7cc4b..b09657e 100644
--- a/README.md
+++ b/README.md
@@ -68,12 +68,15 @@ npm install --save-dev html-w3c-validator start-server-and-test
 
 ```json
 {
+  "$schema": "https://raw.githubusercontent.com/theoludwig/html-w3c-validator/main/schema/html-w3c-validatorrc-schema.json",
+
+  // URLs to validate.
   "urls": ["http://127.0.0.1:3000/", "http://127.0.0.1:3000/about"],
 
-  // You can also specify HTML files instead of URLs
+  // Files to validate.
   "files": ["./index.html", "./about.html"],
 
-  // Specify the severities of the validator (default: ["warning", "error"])
+  // Specify the severities of the validator messages to report. (default: ["warning", "error"])
   "severities": ["info", "warning", "error"]
 }
 ```
diff --git a/example/.html-w3c-validatorrc.json b/example/.html-w3c-validatorrc.json
index 17ac9ce..1568aa3 100644
--- a/example/.html-w3c-validatorrc.json
+++ b/example/.html-w3c-validatorrc.json
@@ -1,4 +1,5 @@
 {
+  "$schema": "https://raw.githubusercontent.com/theoludwig/html-w3c-validator/develop/schema/html-w3c-validatorrc-schema.json",
   "urls": ["http://127.0.0.1:3000/", "http://127.0.0.1:3000/about"],
   "files": ["./build/index.html", "./build/about.html"]
 }
diff --git a/schema/html-w3c-validatorrc-schema.json b/schema/html-w3c-validatorrc-schema.json
new file mode 100644
index 0000000..15f7394
--- /dev/null
+++ b/schema/html-w3c-validatorrc-schema.json
@@ -0,0 +1,47 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "$id": "https://raw.githubusercontent.com/theoludwig/html-w3c-validator/main/schema/html-w3c-validatorrc-schema.json",
+  "title": "html-w3c-validator configuration schema",
+  "type": "object",
+  "properties": {
+    "$schema": {
+      "description": "JSON Schema URI",
+      "type": "string",
+      "default": "https://raw.githubusercontent.com/theoludwig/html-w3c-validator/main/schema/html-w3c-validatorrc-schema.json"
+    },
+    "urls": {
+      "description": "URLs to validate.",
+      "type": "array",
+      "default": [],
+      "minItems": 1,
+      "items": {
+        "description": "URL to validate.",
+        "type": "string",
+        "minLength": 1
+      }
+    },
+    "files": {
+      "description": "Files to validate.",
+      "type": "array",
+      "minItems": 1,
+      "default": [],
+      "items": {
+        "description": "File to validate.",
+        "type": "string",
+        "minLength": 1
+      }
+    },
+    "severities": {
+      "description": "Specify the severities of the validator messages to report.",
+      "type": "array",
+      "minItems": 1,
+      "default": ["warning", "error"],
+      "items": {
+        "description": "Severity to report.",
+        "type": "string",
+        "enum": ["error", "warning", "info"]
+      }
+    }
+  },
+  "additionalProperties": false
+}
diff --git a/src/__test__/fixtures/error-config-invalid-files-and-urls/.html-w3c-validatorrc.json b/src/__test__/fixtures/error-config-invalid-files-and-urls/.html-w3c-validatorrc.json
index bc3240a..2473aa3 100644
--- a/src/__test__/fixtures/error-config-invalid-files-and-urls/.html-w3c-validatorrc.json
+++ b/src/__test__/fixtures/error-config-invalid-files-and-urls/.html-w3c-validatorrc.json
@@ -1,4 +1,5 @@
 {
+  "$schema": "https://raw.githubusercontent.com/theoludwig/html-w3c-validator/develop/schema/html-w3c-validatorrc-schema.json",
   "urls": [],
   "files": []
 }
diff --git a/src/__test__/fixtures/error-config-invalid-files/.html-w3c-validatorrc.json b/src/__test__/fixtures/error-config-invalid-files/.html-w3c-validatorrc.json
index 4895148..ff4f33c 100644
--- a/src/__test__/fixtures/error-config-invalid-files/.html-w3c-validatorrc.json
+++ b/src/__test__/fixtures/error-config-invalid-files/.html-w3c-validatorrc.json
@@ -1,3 +1,4 @@
 {
+  "$schema": "https://raw.githubusercontent.com/theoludwig/html-w3c-validator/develop/schema/html-w3c-validatorrc-schema.json",
   "files": "Invalid"
 }
diff --git a/src/__test__/fixtures/error-config-invalid-severities-empty/.html-w3c-validatorrc.json b/src/__test__/fixtures/error-config-invalid-severities-empty/.html-w3c-validatorrc.json
index 698033e..119db2b 100644
--- a/src/__test__/fixtures/error-config-invalid-severities-empty/.html-w3c-validatorrc.json
+++ b/src/__test__/fixtures/error-config-invalid-severities-empty/.html-w3c-validatorrc.json
@@ -1,4 +1,5 @@
 {
+  "$schema": "https://raw.githubusercontent.com/theoludwig/html-w3c-validator/develop/schema/html-w3c-validatorrc-schema.json",
   "files": ["./index.html"],
   "severities": []
 }
diff --git a/src/__test__/fixtures/error-config-invalid-severities/.html-w3c-validatorrc.json b/src/__test__/fixtures/error-config-invalid-severities/.html-w3c-validatorrc.json
index 4d31b58..309f6fb 100644
--- a/src/__test__/fixtures/error-config-invalid-severities/.html-w3c-validatorrc.json
+++ b/src/__test__/fixtures/error-config-invalid-severities/.html-w3c-validatorrc.json
@@ -1,4 +1,5 @@
 {
+  "$schema": "https://raw.githubusercontent.com/theoludwig/html-w3c-validator/develop/schema/html-w3c-validatorrc-schema.json",
   "files": ["./index.html"],
   "severities": ["errors-invalid"]
 }
diff --git a/src/__test__/fixtures/error-config-invalid-urls/.html-w3c-validatorrc.json b/src/__test__/fixtures/error-config-invalid-urls/.html-w3c-validatorrc.json
index ae90f38..9354c6b 100644
--- a/src/__test__/fixtures/error-config-invalid-urls/.html-w3c-validatorrc.json
+++ b/src/__test__/fixtures/error-config-invalid-urls/.html-w3c-validatorrc.json
@@ -1,3 +1,4 @@
 {
+  "$schema": "https://raw.githubusercontent.com/theoludwig/html-w3c-validator/develop/schema/html-w3c-validatorrc-schema.json",
   "urls": "Invalid"
 }
diff --git a/src/__test__/fixtures/error-invalid-files-paths-to-check/.html-w3c-validatorrc.json b/src/__test__/fixtures/error-invalid-files-paths-to-check/.html-w3c-validatorrc.json
index 9e21d03..4dcd737 100644
--- a/src/__test__/fixtures/error-invalid-files-paths-to-check/.html-w3c-validatorrc.json
+++ b/src/__test__/fixtures/error-invalid-files-paths-to-check/.html-w3c-validatorrc.json
@@ -1,3 +1,4 @@
 {
+  "$schema": "https://raw.githubusercontent.com/theoludwig/html-w3c-validator/develop/schema/html-w3c-validatorrc-schema.json",
   "files": ["./index.html"]
 }
diff --git a/src/__test__/fixtures/error-invalid-w3c-html/.html-w3c-validatorrc.json b/src/__test__/fixtures/error-invalid-w3c-html/.html-w3c-validatorrc.json
index a4a2392..4d035b7 100644
--- a/src/__test__/fixtures/error-invalid-w3c-html/.html-w3c-validatorrc.json
+++ b/src/__test__/fixtures/error-invalid-w3c-html/.html-w3c-validatorrc.json
@@ -1,3 +1,4 @@
 {
+  "$schema": "https://raw.githubusercontent.com/theoludwig/html-w3c-validator/develop/schema/html-w3c-validatorrc-schema.json",
   "files": ["./build/index.html", "./build/about.html"]
 }
diff --git a/src/__test__/fixtures/success/.html-w3c-validatorrc.json b/src/__test__/fixtures/success/.html-w3c-validatorrc.json
index a4a2392..4d035b7 100644
--- a/src/__test__/fixtures/success/.html-w3c-validatorrc.json
+++ b/src/__test__/fixtures/success/.html-w3c-validatorrc.json
@@ -1,3 +1,4 @@
 {
+  "$schema": "https://raw.githubusercontent.com/theoludwig/html-w3c-validator/develop/schema/html-w3c-validatorrc-schema.json",
   "files": ["./build/index.html", "./build/about.html"]
 }