diff --git a/src/main/kotlin/chatserver/ChatServer.kt b/src/main/kotlin/chatserver/ChatServer.kt
index 2dfc874..9ccedf0 100644
--- a/src/main/kotlin/chatserver/ChatServer.kt
+++ b/src/main/kotlin/chatserver/ChatServer.kt
@@ -10,4 +10,5 @@ val chatServerModule =
     module {
         includes(chatServerProfilesModule, chatServerMessagesModule, chatServerPresenceModule)
         factoryOf(::ChatRepositories)
+        factoryOf(::LoggedInUserId)
     }
diff --git a/src/main/kotlin/chatserver/LoggedInUserId.kt b/src/main/kotlin/chatserver/LoggedInUserId.kt
new file mode 100644
index 0000000..249e0f7
--- /dev/null
+++ b/src/main/kotlin/chatserver/LoggedInUserId.kt
@@ -0,0 +1,8 @@
+package chatserver
+
+import io.github.jan.supabase.SupabaseClient
+import io.github.jan.supabase.auth.auth
+
+class LoggedInUserId(private val client: SupabaseClient) {
+    operator fun invoke(): String = client.auth.currentUserOrNull()?.id.orEmpty()
+}
diff --git a/src/main/kotlin/chatserver/ProfileResult.kt b/src/main/kotlin/chatserver/ProfileResult.kt
index 2dca804..633c84c 100644
--- a/src/main/kotlin/chatserver/ProfileResult.kt
+++ b/src/main/kotlin/chatserver/ProfileResult.kt
@@ -1,15 +1,16 @@
 package chatserver
 
 import chatserver.ReadChatRepository.ReadResult
+import chatserver.profiles.SupabaseProfilesRepository.Profile
 
 data class ProfileResult(
     override val isOk: Boolean,
-    override val item: Map<String, String>,
+    override val item: Map<String, Profile>,
     override val error: Exception?,
 ) :
-    ReadResult<Map<String, String>> {
+    ReadResult<Map<String, Profile>> {
     companion object {
-        fun ok(item: Map<String, String>): ProfileResult = ProfileResult(true, item, null)
+        fun ok(item: Map<String, Profile>): ProfileResult = ProfileResult(true, item, null)
 
         fun fail(e: Exception? = null): ProfileResult = ProfileResult(false, emptyMap(), e)
     }
diff --git a/src/main/kotlin/chatserver/profiles/ChatServerProfiles.kt b/src/main/kotlin/chatserver/profiles/ChatServerProfiles.kt
index 1b3816d..2e0e185 100644
--- a/src/main/kotlin/chatserver/profiles/ChatServerProfiles.kt
+++ b/src/main/kotlin/chatserver/profiles/ChatServerProfiles.kt
@@ -15,4 +15,13 @@ val chatServerProfilesModule =
                 ),
             )
         }
+        single {
+            SupabaseProfilesRepository(
+                get(),
+                get(),
+                CoroutineScope(
+                    SupervisorJob() + get<RokyDispatchers>().io,
+                ),
+            )
+        }
     }
diff --git a/src/main/kotlin/chatserver/profiles/LocalProfilesRepository.kt b/src/main/kotlin/chatserver/profiles/LocalProfilesRepository.kt
index 759ad0b..cccaa90 100644
--- a/src/main/kotlin/chatserver/profiles/LocalProfilesRepository.kt
+++ b/src/main/kotlin/chatserver/profiles/LocalProfilesRepository.kt
@@ -7,6 +7,7 @@ import chatserver.ReadChatRepository
 import chatserver.SubscribeChatRepository
 import chatserver.WriteChatRepository
 import chatserver.messages.LocalChatMessages
+import chatserver.profiles.SupabaseProfilesRepository.Profile
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.Flow
@@ -33,7 +34,7 @@ class LocalProfilesRepository(
         scope.launch(dispatchers.default) {
             while (true) {
                 val users = LocalChatMessages.sampleUsers.shuffled()
-                state.value = users.associateWith { it }.let(ProfileResult::ok)
+                state.value = users.associateWith { Profile(it, it) }.let(ProfileResult::ok)
                 delay(5.seconds)
             }
         }
@@ -50,7 +51,7 @@ class LocalProfilesRepository(
                 delay(2.seconds)
                 check(item.isValidUsername()) { "Could not assign current username." }
                 val profiles = latest().item.toMutableMap()
-                profiles[item] = item
+                profiles[item] = Profile(item, item)
                 state.value = ok(profiles)
             } catch (e: Exception) {
                 state.value = ProfileResult.fail(e)
diff --git a/src/main/kotlin/chatserver/profiles/SupabaseProfilesRepository.kt b/src/main/kotlin/chatserver/profiles/SupabaseProfilesRepository.kt
new file mode 100644
index 0000000..fc20dc2
--- /dev/null
+++ b/src/main/kotlin/chatserver/profiles/SupabaseProfilesRepository.kt
@@ -0,0 +1,74 @@
+package chatserver.profiles
+
+import chatserver.*
+import io.github.jan.supabase.SupabaseClient
+import io.github.jan.supabase.annotations.SupabaseExperimental
+import io.github.jan.supabase.postgrest.from
+import io.github.jan.supabase.realtime.selectAsFlow
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.flow.*
+import kotlinx.coroutines.launch
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+class SupabaseProfilesRepository(
+    private val client: SupabaseClient,
+    private val userId: LoggedInUserId,
+    private val scope: CoroutineScope,
+) : ReadChatRepository<ProfileResult>, WriteChatRepository<String>, SubscribeChatRepository {
+    private val profiles: MutableStateFlow<ProfileResult> = MutableStateFlow(ProfileResult.ok(emptyMap()))
+
+    override fun latest(): ProfileResult = profiles.value
+
+    override fun observe(): Flow<ProfileResult> = profiles.asStateFlow()
+
+    override fun write(requestedUsername: String) {
+        require(requestedUsername.isBlank()) {
+            "Requested username must not be blank."
+        }
+        val id =
+            userId().ifBlank {
+                throw IllegalStateException("User ID must not be blank.")
+            }
+        val currentUsername = latest().item[id]?.username
+        check(currentUsername == requestedUsername) {
+            "Current username must not match requested username."
+        }
+        scope.launch {
+            try {
+                client.from("profiles")
+                    .update({
+                        set("username", requestedUsername)
+                    }) {
+                        filter {
+                            eq("id", id)
+                        }
+                    }
+            } catch (e: Exception) {
+                profiles.value = ProfileResult.fail(e)
+            }
+        }
+    }
+
+    @OptIn(SupabaseExperimental::class)
+    override fun subscribe() {
+        client.from("profiles")
+            .selectAsFlow(Profile::id)
+            .map { it.associateBy(Profile::id) }
+            .map { ProfileResult.ok(it) }
+            .onEach { profiles.value = it }
+            .catch { println(it) }
+            .launchIn(scope)
+    }
+
+    override fun unsubscribe() {
+        scope.cancel()
+    }
+
+    @Serializable
+    data class Profile(
+        @SerialName("id") val id: String,
+        @SerialName("username") val username: String,
+    )
+}
diff --git a/src/test/kotlin/profile/ProfilePresenterTest.kt b/src/test/kotlin/profile/ProfilePresenterTest.kt
index 4c33f01..2ef1378 100644
--- a/src/test/kotlin/profile/ProfilePresenterTest.kt
+++ b/src/test/kotlin/profile/ProfilePresenterTest.kt
@@ -4,6 +4,7 @@ import arch.RokyDispatchers
 import chatserver.ProfileResult
 import chatserver.ReadChatRepository
 import chatserver.WriteChatRepository
+import chatserver.profiles.SupabaseProfilesRepository.Profile
 import io.mockk.every
 import io.mockk.mockk
 import io.mockk.verify
@@ -43,13 +44,13 @@ class ProfilePresenterTest {
         }
         val writeUsername: WriteChatRepository<String> = mockk()
         every { writeUsername.write(any()) } answers {
-            val user = it.invocation.args [0] as String
+            val user = it.invocation.args[0] as String
             usernames.value =
                 if (user == INVALID_USER) {
                     ProfileResult.fail(RuntimeException())
                 } else {
                     val currentUsernames = usernames.value.item.toMutableMap()
-                    currentUsernames[user] = user
+                    currentUsernames[user] = Profile(user, user)
                     ProfileResult.ok(currentUsernames)
                 }
         }