Mattermost

Open source · OSI-approvedStatus: unknown

Team messaging for organisations that cannot use hosted chat

Mattermost is channel-based team chat designed for environments where the message history has to stay inside a boundary: defence, healthcare, and regulated finance are its natural constituency.

It covers the familiar ground - channels, threads, search, integrations - and adds the compliance exports, audit logging, and air-gapped deployment those environments require.

Decisive facts

Channels, threads, and search with full message history retained
Runs air-gapped with no outbound connectivity required
Compliance exports and audit logging
Playbooks for incident response workflows
Desktop and mobile clients you can distribute yourself

Team Chat & Meetings self-hosted go react chat compliance

Alternatives to Mattermost

Slack

Channel based team messaging with a large integration ecosystem

Similar source projects

Computed from shared categories, tags, and license. This is similarity, not an alternative claim, and paid weight is always zero.

Jitsi MeetOpen

Video meetings with no account and no install

Stars25.6K

Commit2d ago

LicenseApache-2.0

Jitsi Meet gets to a working video call faster than anything else: open a URL, share it, done. No accounts, no downloads, no meeting identifiers to read out.

Alternative tozoom

1 shared category; 1 shared tag · organic similarity 700

ChatwootOpen

Customer conversations from every channel in one inbox

Stars24.7K

Commit1d ago

LicenseMIT

Chatwoot collects website chat, email, WhatsApp, Instagram, and SMS into a single agent inbox with shared assignment, canned replies, and a help centre.

Alternative tointercom zendesk

1 shared category; 1 shared tag · organic similarity 700

GrafanaOpen

Dashboards over whatever data you already store

Stars71.2K

Commit8h ago

LicenseAGPL-3.0

Grafana is the visualisation layer that sits above other systems rather than a monitoring stack of its own. It queries Prometheus, Loki, PostgreSQL, ClickHouse, and dozens of other sources, and puts them on the same dashboard.

Alternative todatadog

2 shared tags; same AGPL-3.0 license · organic similarity 300

EnteOpen

End-to-end encrypted photo storage across devices

Stars28.6K

Commit8h ago

LicenseAGPL-3.0

Ente stores photos and videos encrypted on the client, so the server holds ciphertext it cannot read. Sync, albums, and sharing all work on top of that constraint rather than around it.

Alternative togoogle photos

2 shared tags; same AGPL-3.0 license · organic similarity 300

FocalboardOpen

Project boards that work offline and stay local

Stars24.3K

Commit2mo ago

LicenseMIT

Focalboard is a board and table tool that runs as a desktop application against local files, or as a server for a team. It covers the kanban, table, and calendar views most planning needs without a subscription or an account.

Alternative tonotion asana

3 shared tags · organic similarity 300

ListmonkOpen

Self-hosted newsletter and mailing list manager

Stars18.4K

Commit3d ago

LicenseAGPL-3.0

Listmonk is a single Go binary and a Postgres database that handles subscriber lists, segmentation, campaigns, and bounce processing at a scale that would be expensive on a hosted platform.

Alternative tomailchimp

2 shared tags; same AGPL-3.0 license · organic similarity 300