Self-hosted alternatives to Stack Overflow

A questions-and-answers (Q&A) platform hosted by you. Below are 12 open source options you host on your own server — with no monthly per-user fee and full control of your data.

Mastodon

★ 50,053

Mastodon is a decentralized social network (the fediverse) where each server is independent and interconnected. By hosting your own instance, you set the community rules and no algorithm controls your feed.

Communication - Social Networks and Forums AGPL-3.0

Discourse

★ 47,306

Discourse is the modern forum and community platform, with topics, moderation and gamification. Self-hosted, it's the way to have your own discussion space without depending on social-media groups.

Communication - Social Networks and Forums GPL-2.0

Flarum

★ 16,325

Delightfully simple forums. Flarum is the next-generation forum software that makes online discussion fun again.

Communication - Social Networks and Forums MIT

Answer

★ 15,562

Knowledge-based community software. You can use it to quickly build your Q&A community for product technical support, customer support, user communication, and more.

Communication - Social Networks and Forums Apache-2.0

NodeBB

★ 15,143

Forum software built for the modern web.

Communication - Social Networks and Forums GPL-3.0

Lemmy

★ 14,453

Link aggregator for the fediverse (alternative to Reddit).

Communication - Social Networks and Forums AGPL-3.0

diaspora*

★ 13,656

Distributed social networking server.

Communication - Social Networks and Forums AGPL-3.0

Misskey

★ 11,212

Decentralized app-like microblogging server/SNS for the Fediverse, using the ActivityPub protocol like GNU social and Mastodon.

Communication - Social Networks and Forums AGPL-3.0

PixelFed

★ 7,010

Ethical photo sharing platform, powered by ActivityPub federation (alternative to Instagram).

Communication - Social Networks and Forums AGPL-3.0

HumHub

★ 6,694

Flexible kit for private social networks.

Communication - Social Networks and Forums AGPL-3.0

remark42

★ 5,528

Lightweight and simple comment engine, which doesn't spy on users. It can be embedded into blogs, articles or any other place where readers add comments.

Communication - Social Networks and Forums MIT

Isso

★ 5,286

Lightweight commenting server written in Python and Javascript. It aims to be a drop-in replacement for Disqus.

Communication - Social Networks and Forums MIT

Frequently asked questions

Is there a free self-hosted alternative to Stack Overflow?

Yes. We've gathered 12 self-hosted, open source alternatives to Stack Overflow — including Mastodon, Discourse, Flarum. You run all of them on your own server.

What is the best open source alternative to Stack Overflow?

Mastodon is one of the most popular (50,053 GitHub stars). The "best" depends on your case — compare the options below.

Do I need a server to replace Stack Overflow?

Yes. You can use a home server (homelab) or a cheap VPS (from ~€4/mo). See the hosting suggestions on this page.