diff --git a/briar-headless/README.md b/briar-headless/README.md
index eda86afbe..b608e5436 100644
--- a/briar-headless/README.md
+++ b/briar-headless/README.md
@@ -183,6 +183,18 @@ Note that it's also possible to add contacts nearby via Bluetooth/Wifi or
 introductions. In these cases contacts omit the `pendingContact` state and
 directly become `contact`s.
 
+### Changing alias of a contact
+
+`PUT /v1/contacts/{contactId}/alias`
+
+The alias should be posted as a JSON object:
+
+```json
+{
+    "alias": "A nickname for the new contact"
+}
+```
+
 ### Removing a contact
 
 `DELETE /v1/contacts/{contactId}`
diff --git a/briar-headless/src/main/java/org/briarproject/briar/headless/Router.kt b/briar-headless/src/main/java/org/briarproject/briar/headless/Router.kt
index a268607b0..598c2a815 100644
--- a/briar-headless/src/main/java/org/briarproject/briar/headless/Router.kt
+++ b/briar-headless/src/main/java/org/briarproject/briar/headless/Router.kt
@@ -81,6 +81,9 @@ constructor(
                     path("/:contactId") {
                         delete { ctx -> contactController.delete(ctx) }
                     }
+                    path("/:contactId/alias") {
+                        put { ctx -> contactController.setContactAlias(ctx) }
+                    }
                 }
                 path("/messages/:contactId") {
                     get { ctx -> messagingController.list(ctx) }
diff --git a/briar-headless/src/main/java/org/briarproject/briar/headless/contact/ContactController.kt b/briar-headless/src/main/java/org/briarproject/briar/headless/contact/ContactController.kt
index f936004fb..88d26416b 100644
--- a/briar-headless/src/main/java/org/briarproject/briar/headless/contact/ContactController.kt
+++ b/briar-headless/src/main/java/org/briarproject/briar/headless/contact/ContactController.kt
@@ -9,6 +9,7 @@ interface ContactController {
     fun addPendingContact(ctx: Context): Context
     fun listPendingContacts(ctx: Context): Context
     fun removePendingContact(ctx: Context): Context
+    fun setContactAlias(ctx: Context): Context
     fun delete(ctx: Context): Context
 
 }
diff --git a/briar-headless/src/main/java/org/briarproject/briar/headless/contact/ContactControllerImpl.kt b/briar-headless/src/main/java/org/briarproject/briar/headless/contact/ContactControllerImpl.kt
index b7e542b61..6815f2c52 100644
--- a/briar-headless/src/main/java/org/briarproject/briar/headless/contact/ContactControllerImpl.kt
+++ b/briar-headless/src/main/java/org/briarproject/briar/headless/contact/ContactControllerImpl.kt
@@ -92,9 +92,7 @@ constructor(
         val link = ctx.getFromJson(objectMapper, "link")
         val alias = ctx.getFromJson(objectMapper, "alias")
         if (!LINK_REGEX.matcher(link).find()) throw BadRequestResponse("Invalid Link")
-        val aliasUtf8 = toUtf8(alias)
-        if (aliasUtf8.isEmpty() || aliasUtf8.size > MAX_AUTHOR_NAME_LENGTH)
-            throw BadRequestResponse("Invalid Alias")
+        checkAliasLength(alias)
         val pendingContact = contactManager.addPendingContact(link, alias)
         return ctx.json(pendingContact.output())
     }
@@ -125,6 +123,18 @@ constructor(
         return ctx
     }
 
+    override fun setContactAlias(ctx: Context): Context {
+        val contactId = ctx.getContactIdFromPathParam()
+        val alias = ctx.getFromJson(objectMapper, "alias")
+        checkAliasLength(alias)
+        try {
+            contactManager.setContactAlias(contactId, alias)
+        } catch (e: NoSuchContactException) {
+            throw NotFoundResponse()
+        }
+        return ctx
+    }
+
     override fun delete(ctx: Context): Context {
         val contactId = ctx.getContactIdFromPathParam()
         try {
@@ -135,4 +145,10 @@ constructor(
         return ctx
     }
 
+    private fun checkAliasLength(alias: String) {
+        val aliasUtf8 = toUtf8(alias)
+        if (aliasUtf8.isEmpty() || aliasUtf8.size > MAX_AUTHOR_NAME_LENGTH)
+            throw BadRequestResponse("Invalid Alias")
+    }
+
 }
diff --git a/briar-headless/src/test/java/org/briarproject/briar/headless/contact/ContactControllerTest.kt b/briar-headless/src/test/java/org/briarproject/briar/headless/contact/ContactControllerTest.kt
index a169e8eef..7a8476b1e 100644
--- a/briar-headless/src/test/java/org/briarproject/briar/headless/contact/ContactControllerTest.kt
+++ b/briar-headless/src/test/java/org/briarproject/briar/headless/contact/ContactControllerTest.kt
@@ -6,6 +6,7 @@ import io.javalin.plugin.json.JavalinJson.toJson
 import io.mockk.Runs
 import io.mockk.every
 import io.mockk.just
+import io.mockk.mockkStatic
 import io.mockk.runs
 import org.briarproject.bramble.api.Pair
 import org.briarproject.bramble.api.contact.Contact
@@ -27,6 +28,7 @@ import org.briarproject.bramble.test.TestUtils.getPendingContact
 import org.briarproject.bramble.test.TestUtils.getRandomBytes
 import org.briarproject.bramble.util.StringUtils.getRandomString
 import org.briarproject.briar.headless.ControllerTest
+import org.briarproject.briar.headless.getFromJson
 import org.briarproject.briar.headless.json.JsonDict
 import org.junit.jupiter.api.Assertions.assertNotNull
 import org.junit.jupiter.api.Assertions.assertThrows
@@ -194,6 +196,66 @@ internal class ContactControllerTest : ControllerTest() {
         }
     }
 
+    @Test
+    fun testSetContactAlias() {
+        mockkStatic("org.briarproject.briar.headless.RouterKt")
+        every { ctx.pathParam("contactId") } returns "1"
+        every { ctx.getFromJson(objectMapper, "alias") } returns "foo"
+        every { contactManager.setContactAlias(ContactId(1), "foo") } just Runs
+        controller.setContactAlias(ctx)
+    }
+
+    @Test
+    fun testSetContactAliasInvalidId() {
+        mockkStatic("org.briarproject.briar.headless.RouterKt")
+        every { ctx.pathParam("contactId") } returns "foo"
+        every { ctx.getFromJson(objectMapper, "alias") } returns "bar"
+        assertThrows(NotFoundResponse::class.java) {
+            controller.setContactAlias(ctx)
+        }
+    }
+
+    @Test
+    fun testSetContactAliasNonexistentId() {
+        mockkStatic("org.briarproject.briar.headless.RouterKt")
+        every { ctx.pathParam("contactId") } returns "1"
+        every { ctx.getFromJson(objectMapper, "alias") } returns "foo"
+        every { contactManager.setContactAlias(ContactId(1), "foo") } throws NotFoundResponse()
+        assertThrows(NotFoundResponse::class.java) {
+            controller.setContactAlias(ctx)
+        }
+    }
+
+    @Test
+    fun testSetContactAliasInvalid() {
+        mockkStatic("org.briarproject.briar.headless.RouterKt")
+        every { ctx.pathParam("contactId") } returns "1"
+        every { ctx.getFromJson(objectMapper, "alias") } returns getRandomString(MAX_AUTHOR_NAME_LENGTH + 1)
+        assertThrows(BadRequestResponse::class.java) {
+            controller.setContactAlias(ctx)
+        }
+    }
+
+    @Test
+    fun testSetContactAliasEmpty() {
+        mockkStatic("org.briarproject.briar.headless.RouterKt")
+        every { ctx.pathParam("contactId") } returns "1"
+        every { ctx.getFromJson(objectMapper, "alias") } returns ""
+        assertThrows(BadRequestResponse::class.java) {
+            controller.setContactAlias(ctx)
+        }
+    }
+
+    @Test
+    fun testSetContactAliasMissing() {
+        mockkStatic("org.briarproject.briar.headless.RouterKt")
+        every { ctx.pathParam("contactId") } returns "1"
+        every { ctx.body() } returns ""
+        assertThrows(BadRequestResponse::class.java) {
+            controller.setContactAlias(ctx)
+        }
+    }
+
     @Test
     fun testDelete() {
         every { ctx.pathParam("contactId") } returns "1"