diff --git a/src/main/kotlin/app/api/Api.kt b/src/main/kotlin/app/api/Api.kt
index a2a5658e..b42f9a5b 100644
--- a/src/main/kotlin/app/api/Api.kt
+++ b/src/main/kotlin/app/api/Api.kt
@@ -3,6 +3,7 @@
 
 package app.api
 
+import app.model.Author
 import app.model.Commit
 import app.model.Fact
 import app.model.Repo
@@ -20,4 +21,5 @@ interface Api {
     fun postCommits(commitsList: List<Commit>): Result<Unit>
     fun deleteCommits(commitsList: List<Commit>): Result<Unit>
     fun postFacts(factsList: List<Fact>): Result<Unit>
+    fun postAuthors(authorsList: List<Author>): Result<Unit>
 }
diff --git a/src/main/kotlin/app/api/ApiError.kt b/src/main/kotlin/app/api/ApiError.kt
index 981f1d5b..1093cf1e 100644
--- a/src/main/kotlin/app/api/ApiError.kt
+++ b/src/main/kotlin/app/api/ApiError.kt
@@ -30,9 +30,9 @@ class ApiError(exception: Exception) : Exception(exception.message) {
     get() = AUTH_ERROR_CODES.contains(httpStatusCode)
 
     constructor(fuelError: FuelError) : this(fuelError as Exception) {
-        httpStatusCode = fuelError.response.httpStatusCode
-        httpResponseMessage = fuelError.response.httpResponseMessage
-        if (fuelError.response.httpResponseHeaders["Content-Type"]
+        httpStatusCode = fuelError.response.statusCode
+        httpResponseMessage = fuelError.response.responseMessage
+        if (fuelError.response.headers["Content-Type"]
             ?.contains("application/octet-stream") == true) {
             try {
                 serverErrors = Errors(fuelError.response.data).errors
diff --git a/src/main/kotlin/app/api/MockApi.kt b/src/main/kotlin/app/api/MockApi.kt
index c08688ec..042e7aa5 100644
--- a/src/main/kotlin/app/api/MockApi.kt
+++ b/src/main/kotlin/app/api/MockApi.kt
@@ -4,6 +4,7 @@
 package app.api
 
 import app.Logger
+import app.model.Author
 import app.model.Commit
 import app.model.Repo
 import app.model.Fact
@@ -17,6 +18,7 @@ class MockApi(  // GET requests.
     var receivedRepos: MutableList<Repo> = mutableListOf()
     var receivedAddedCommits: MutableList<Commit> = mutableListOf()
     var receivedFacts: MutableList<Fact> = mutableListOf()
+    var receivedAuthors: MutableList<Author> = mutableListOf()
 
     // DELETE requests.
     var receivedDeletedCommits: MutableList<Commit> = mutableListOf()
@@ -58,8 +60,15 @@ class MockApi(  // GET requests.
     }
 
     override fun postFacts(factsList: List<Fact>): Result<Unit> {
-        Logger.debug { "MockApi: postStats request (${factsList.size} stats)" }
+        Logger.debug { "MockApi: postFacts request (${factsList.size} facts)" }
         receivedFacts.addAll(factsList)
         return Result()
     }
+
+    override fun postAuthors(authorsList: List<Author>): Result<Unit> {
+        Logger.debug { "MockApi: postAuthors request (${authorsList.size} " +
+            "stats)" }
+        receivedAuthors.addAll(authorsList)
+        return Result()
+    }
 }
diff --git a/src/main/kotlin/app/api/ServerApi.kt b/src/main/kotlin/app/api/ServerApi.kt
index f475c6a4..a7a03d85 100644
--- a/src/main/kotlin/app/api/ServerApi.kt
+++ b/src/main/kotlin/app/api/ServerApi.kt
@@ -6,6 +6,8 @@ package app.api
 import app.BuildConfig
 import app.Logger
 import app.config.Configurator
+import app.model.Author
+import app.model.AuthorGroup
 import app.model.Commit
 import app.model.CommitGroup
 import app.model.Fact
@@ -105,6 +107,11 @@ class ServerApi (private val configurator: Configurator) : Api {
                              .body(facts.serialize())
     }
 
+    private fun createRequestPostAuthors(authors: AuthorGroup): Request {
+        return post("/authors").header(getContentTypeHeader())
+                               .body(authors.serialize())
+    }
+
     private fun <T> makeRequest(request: Request,
                                 requestName: String,
                                 parser: (ByteArray) -> T): Result<T> {
@@ -177,4 +184,9 @@ class ServerApi (private val configurator: Configurator) : Api {
         val facts = FactGroup(factsList)
         return makeRequest(createRequestPostFacts(facts), "postFacts", {})
     }
+
+    override fun postAuthors(authorsList: List<Author>): Result<Unit> {
+        val authors = AuthorGroup(authorsList)
+        return makeRequest(createRequestPostAuthors(authors), "postAuthors", {})
+    }
 }
diff --git a/src/main/kotlin/app/hashers/RepoHasher.kt b/src/main/kotlin/app/hashers/RepoHasher.kt
index 069a6aa1..7e4c71b7 100644
--- a/src/main/kotlin/app/hashers/RepoHasher.kt
+++ b/src/main/kotlin/app/hashers/RepoHasher.kt
@@ -6,6 +6,7 @@ package app.hashers
 import app.Logger
 import app.api.Api
 import app.config.Configurator
+import app.model.Author
 import app.model.LocalRepo
 import app.model.Repo
 import app.utils.HashingException
@@ -51,6 +52,9 @@ class RepoHasher(private val localRepo: LocalRepo, private val api: Api,
                 // Notify server about new contributor and his email.
                 postRepoToServer()
             }
+
+            postAuthorsToServer(filteredEmails)
+
             // Get repo setup (commits, emails to hash) from server.
             getRepoFromServer()
 
@@ -130,6 +134,12 @@ class RepoHasher(private val localRepo: LocalRepo, private val api: Api,
         Logger.debug { serverRepo.toString() }
     }
 
+    private fun postAuthorsToServer(emails: HashSet<String>) {
+        api.postAuthors(emails.map { email ->
+            Author(email=email, repo=serverRepo)
+        }).onErrorThrow()
+    }
+
     private fun initServerRepo(initCommitRehash: String) {
         serverRepo = Repo(userEmail = localRepo.author.email)
         serverRepo.initialCommitRehash = initCommitRehash
diff --git a/src/main/kotlin/app/model/Author.kt b/src/main/kotlin/app/model/Author.kt
index 6f690f53..f302cc11 100644
--- a/src/main/kotlin/app/model/Author.kt
+++ b/src/main/kotlin/app/model/Author.kt
@@ -3,10 +3,40 @@
 
 package app.model
 
+import app.Protos
+import com.google.protobuf.InvalidProtocolBufferException
+import java.security.InvalidParameterException
+
 /**
  * Commit author.
  */
-data class Author(var name: String = "", var email: String = "") {
+data class Author(
+    var name: String = "",
+    var email: String = "",
+    var repo: Repo = Repo()
+) {
+    @Throws(InvalidParameterException::class)
+    constructor(proto: Protos.Author) : this() {
+        email = proto.email
+        repo = Repo(proto.repoRehash)
+    }
+
+    @Throws(InvalidProtocolBufferException::class)
+    constructor(bytes: ByteArray) : this(Protos.Author.parseFrom(bytes))
+
+    constructor(serialized: String) : this(serialized.toByteArray())
+
+    fun getProto(): Protos.Author {
+        return Protos.Author.newBuilder()
+            .setEmail(email)
+            .setRepoRehash(repo.rehash)
+            .build()
+    }
+
+    fun serialize(): ByteArray {
+        return getProto().toByteArray()
+    }
+
     // Email defines user identity.
     override fun equals(other: Any?): Boolean {
         if (other is Author) {
diff --git a/src/main/kotlin/app/model/AuthorGroup.kt b/src/main/kotlin/app/model/AuthorGroup.kt
new file mode 100644
index 00000000..bf252d78
--- /dev/null
+++ b/src/main/kotlin/app/model/AuthorGroup.kt
@@ -0,0 +1,32 @@
+package app.model
+
+import app.Protos
+import com.google.protobuf.InvalidProtocolBufferException
+import java.security.InvalidParameterException
+
+/**
+ * Group of commit authors.
+ */
+data class AuthorGroup(
+        var authors: List<Author> = listOf()
+) {
+    @Throws(InvalidParameterException::class)
+    constructor(proto: Protos.AuthorGroup) : this() {
+        authors = proto.authorsList.map { it -> Author(it) }
+    }
+
+    @Throws(InvalidProtocolBufferException::class)
+    constructor(bytes: ByteArray) : this(Protos.AuthorGroup.parseFrom(bytes))
+
+    constructor(serialized: String) : this(serialized.toByteArray())
+
+    fun getProto(): Protos.AuthorGroup {
+        return Protos.AuthorGroup.newBuilder()
+                .addAllAuthors(authors.map { it -> it.getProto() })
+                .build()
+    }
+
+    fun serialize(): ByteArray {
+        return getProto().toByteArray()
+    }
+}
diff --git a/src/main/proto/sourcerer.proto b/src/main/proto/sourcerer.proto
index f30a9c9a..f3d11913 100644
--- a/src/main/proto/sourcerer.proto
+++ b/src/main/proto/sourcerer.proto
@@ -72,6 +72,16 @@ message FactGroup {
     repeated Fact facts = 1;
 }
 
+// Used to authors for invitational procedures.
+message Author {
+    string email = 1;
+    string repo_rehash = 2;
+}
+
+message AuthorGroup {
+    repeated Author authors = 1;
+}
+
 // User properties and indentity information about repos.
 message User {
     // List of known repos containing basic information for indentifying repo.