Zulip replaces 4 paid apps
One open-source tool, 4 subscriptions it can stand in for. Each pairing below is curated and verified by hand, with the honest catch spelled out. No votes, no pay-to-list.
licenseApache-2.0
runsyour machine or their cloud
installHosted signup, or run the official install script/Docker deployment on supported Ubuntu or Debian
dataPersistent messages and organization data in PostgreSQL; uploads locally or in S3-compatible storage; exports are tar.gz archives containing JSON and files
setupFree cloud search stops at 10,000 messages; self-hosting needs a Linux VM, DNS/TLS, outgoing email and at least about 2 GB RAM
facts verified 2026-08-10
Email-shaped topics inside team chat; excellent for async work and merciless about naming conversations.
the verdict →all Mattermost Professional alternatives →
Topic-first team chat with full history and excellent search; fewer drive-by messages survive.
the verdict →all Slack Pro alternatives →
The closest free answer: streams hold channels, topics hold threads, and every reply lands somewhere deliberate.
the catchZulip is the closest structural match, but its free cloud search stops at 10,000 messages and self-hosting replaces Twist's managed operations with a Linux service.
the verdict →all Twist alternatives →
Channels become streams and every conversation gets a topic; async teams usually call that an upgrade.
the verdict →all Pumble alternatives →last updated 2026-08-10 · up to $360/yr replaced · no votes, no pay-to-list