diff --git a/clients/c/cosmopolite.c b/clients/c/cosmopolite.c
index 4d4348d..686e040 100644
--- a/clients/c/cosmopolite.c
+++ b/clients/c/cosmopolite.c
@@ -299,7 +299,7 @@ void cosmo_unsubscribe(cosmo *instance, json_t *subject) {
   assert(!pthread_mutex_unlock(&instance->lock));
 }
 
-void cosmo_send_message(cosmo *instance, const json_t *subject, json_t *message) {
+void cosmo_send_message(cosmo *instance, json_t *subject, json_t *message) {
   char sender_message_id[COSMO_UUID_SIZE];
   cosmo_uuid(sender_message_id);
   char *encoded = json_dumps(message, JSON_ENCODE_ANY);
@@ -311,6 +311,49 @@ void cosmo_send_message(cosmo *instance, const json_t *subject, json_t *message)
   free(encoded);
 }
 
+json_t *cosmo_get_messages(cosmo *instance, json_t *subject) {
+  assert(!pthread_mutex_lock(&instance->lock));
+  json_t *subscription = cosmo_find_subscription(instance, subject);
+  if (!subscription) {
+    assert(!pthread_mutex_unlock(&instance->lock));
+    return NULL;
+  }
+  json_t *messages = json_object_get(subscription, "messages");
+  json_t *ret = json_deep_copy(messages);
+  assert(!pthread_mutex_unlock(&instance->lock));
+
+  return ret;
+}
+
+json_t *cosmo_get_last_message(cosmo *instance, json_t *subject) {
+  assert(!pthread_mutex_lock(&instance->lock));
+  json_t *subscription = cosmo_find_subscription(instance, subject);
+  if (!subscription) {
+    assert(!pthread_mutex_unlock(&instance->lock));
+    return NULL;
+  }
+  json_t *messages = json_object_get(subscription, "messages");
+  json_t *last_message = json_array_get(messages, json_array_size(messages) - 1);
+  json_t *ret = json_deep_copy(last_message);
+  assert(!pthread_mutex_unlock(&instance->lock));
+
+  return ret;
+}
+
+json_t *cosmo_get_pins(cosmo *instance, json_t *subject) {
+  assert(!pthread_mutex_lock(&instance->lock));
+  json_t *subscription = cosmo_find_subscription(instance, subject);
+  if (!subscription) {
+    assert(!pthread_mutex_unlock(&instance->lock));
+    return NULL;
+  }
+  json_t *pins = json_object_get(subscription, "pins");
+  json_t *ret = json_deep_copy(pins);
+  assert(!pthread_mutex_unlock(&instance->lock));
+
+  return ret;
+}
+
 cosmo *cosmo_create(const char *base_url, const char *client_id) {
   curl_global_init(CURL_GLOBAL_DEFAULT);
   srandomdev();
diff --git a/clients/c/cosmopolite.h b/clients/c/cosmopolite.h
index 9677fdb..30433be 100644
--- a/clients/c/cosmopolite.h
+++ b/clients/c/cosmopolite.h
@@ -34,15 +34,14 @@ const char *cosmo_current_profile(cosmo *instance);
 json_t *cosmo_subject(const char *name, const char *readable_only_by, const char *writeable_only_by);
 void cosmo_subscribe(cosmo *instance, json_t *subject, const json_int_t messages, const json_int_t last_id);
 void cosmo_unsubscribe(cosmo *instance, json_t *subject);
-void cosmo_send_message(cosmo *instance, const json_t *subject, json_t *message);
+void cosmo_send_message(cosmo *instance, json_t *subject, json_t *message);
 
-// TODO
-json_t *cosmo_get_messages(cosmo *instance, const json_t *subject);
-json_t *cosmo_get_last_message(cosmo *instance, const json_t *subject);
-json_t *cosmo_get_pins(cosmo *instance, const json_t *subject);
+json_t *cosmo_get_messages(cosmo *instance, json_t *subject);
+json_t *cosmo_get_last_message(cosmo *instance, json_t *subject);
+json_t *cosmo_get_pins(cosmo *instance, json_t *subject);
 
 // Hard TODO
-void cosmo_pin(cosmo *instance, const json_t *subject, json_t *message);
-void cosmo_unpin(cosmo *instance, const json_t *subject, json_t *message);
+void cosmo_pin(cosmo *instance, json_t *subject, json_t *message);
+void cosmo_unpin(cosmo *instance, json_t *subject, json_t *message);
 
 #endif