diff --git a/src/activitypub/index.js b/src/activitypub/index.js
index 57227a2e20..478c755c6b 100644
--- a/src/activitypub/index.js
+++ b/src/activitypub/index.js
@@ -7,6 +7,7 @@ const { createHash, createSign, createVerify } = require('crypto');
 const request = require('../request');
 const db = require('../database');
 const user = require('../user');
+const posts = require('../posts');
 const utils = require('../utils');
 const ttl = require('../cache/ttl');
 
@@ -14,6 +15,10 @@ const requestCache = ttl({ ttl: 1000 * 60 * 5 }); // 5 minutes
 const actorCache = ttl({ ttl: 1000 * 60 * 60 * 24 }); // 24 hours
 const ActivityPub = module.exports;
 
+ActivityPub._constants = Object.freeze({
+	publicAddress: 'https://www.w3.org/ns/activitystreams#Public',
+});
+
 ActivityPub.helpers = require('./helpers');
 ActivityPub.inbox = require('./inbox');
 ActivityPub.mocks = require('./mocks');
@@ -59,10 +64,19 @@ ActivityPub.getActor = async (uid, input) => {
 	}
 };
 
-ActivityPub.resolveInboxes = async (uid, ids) => await Promise.all(ids.map(async (id) => {
-	const actor = await ActivityPub.getActor(uid, id);
-	return actor.inbox;
-}));
+ActivityPub.resolveInboxes = async (uid, ids) => {
+	const inboxes = new Set();
+
+	await Promise.all(ids.map(async (id) => {
+		const actor = await ActivityPub.getActor(uid, id);
+		const inbox = actor.sharedInbox || actor.inbox;
+		if (inbox) {
+			inboxes.add(inbox);
+		}
+	}));
+
+	return Array.from(inboxes);
+};
 
 ActivityPub.getPublicKey = async (uid) => {
 	let publicKey;
diff --git a/src/api/activitypub.js b/src/api/activitypub.js
index b8f9813f21..dba7a972c1 100644
--- a/src/api/activitypub.js
+++ b/src/api/activitypub.js
@@ -13,6 +13,7 @@ const nconf = require('nconf');
 const db = require('../database');
 const activitypub = require('../activitypub');
 const user = require('../user');
+const posts = require('../posts');
 
 const activitypubApi = module.exports;
 
@@ -49,3 +50,57 @@ activitypubApi.unfollow = async (caller, { uid: actorId }) => {
 		db.decrObjectField(`user:${caller.uid}`, 'followingRemoteCount'),
 	]);
 };
+
+activitypubApi.create = {};
+
+activitypubApi.create.post = async (caller, { post }) => {
+	const id = `${nconf.get('url')}/post/${post.pid}`;
+	const published = new Date(post.timestamp).toISOString();
+	const [userslug, raw, followers] = await Promise.all([
+		user.getUserField(caller.uid, 'userslug'),
+		posts.getPostField(post.pid, 'content'),
+		db.getSortedSetMembers(`followersRemote:${caller.uid}`),
+	]);
+
+	// todo: post visibility, category privileges integration
+	const recipients = {
+		to: [activitypub._constants.publicAddress],
+		cc: [`${nconf.get('url')}/user/${userslug}/followers`],
+	};
+	const targets = new Set(followers);
+
+	let inReplyTo = null;
+	if (post.toPid) {
+		inReplyTo = activitypub.helpers.isUri(post.toPid) ? post.toPid : id;
+		const parentId = await posts.getPostField(post.toPid, 'uid');
+		if (activitypub.helpers.isUri(parentId)) {
+			recipients.to.unshift(parentId);
+			targets.add(parentId);
+		}
+	}
+
+	const object = {
+		id,
+		type: 'Note',
+		...recipients,
+		inReplyTo,
+		published,
+		url: id,
+		attributedTo: `${nconf.get('url')}/user/${post.user.userslug}`,
+		sensitive: false, // todo
+		content: post.content,
+		source: {
+			content: raw,
+			mediaType: 'text/markdown',
+		},
+		// replies: {}  todo...
+	};
+
+	const payload = {
+		type: 'Create',
+		...recipients,
+		object,
+	};
+
+	await activitypub.send(caller.uid, Array.from(targets), payload);
+};
diff --git a/src/api/topics.js b/src/api/topics.js
index 7a6cabf966..873071cf4a 100644
--- a/src/api/topics.js
+++ b/src/api/topics.js
@@ -8,6 +8,7 @@ const posts = require('../posts');
 const meta = require('../meta');
 const privileges = require('../privileges');
 
+const activitypubApi = require('./activitypub');
 const apiHelpers = require('./helpers');
 
 const { doTopicAction } = apiHelpers;
@@ -79,6 +80,7 @@ topicsAPI.create = async function (caller, data) {
 	socketHelpers.emitToUids('event:new_post', { posts: [result.postData] }, [caller.uid]);
 	socketHelpers.emitToUids('event:new_topic', result.topicData, [caller.uid]);
 	socketHelpers.notifyNew(caller.uid, 'newTopic', { posts: [result.postData], topic: result.topicData });
+	activitypubApi.create.post(caller, { post: result.postData });
 
 	return result.topicData;
 };
@@ -113,6 +115,7 @@ topicsAPI.reply = async function (caller, data) {
 	}
 
 	socketHelpers.notifyNew(caller.uid, 'newPost', result);
+	activitypubApi.create.post(caller, { post: postData });
 
 	return postObj[0];
 };