Mattermost vs Keybase

You don't need to rely on someone else's servers, you can host Mattermost on your own server.

With Docker set up, you can install Mattermost with the following command:

docker run --name mattermost-dev -d --publish 8065:80 mattermost/platform

For other cases, installation instructions can be found here.

Almost all features of Slack are available in Mattermost.

You can download and use it as free for self-hosted server.

Yes, it supports markdown.

Completely end-to-end encrypted.

Users can publish proofs of identity (PGP public key, Twitter, Facebook, etc).

Free (as in beer) and Open Source Software.

Securely share files.

For sharing files publicly.

250GB of free storage for encrypted files in a team.

Teams can be public with open access or admin-approved access. Opt-in to list public teams.

Teams can be completely private (access granted via admin-approval only, not publicly listed).

Encrypted private or team Git repositories with automatic commit signatures.

Based on blockchain technology.

View/verify the cryptographic signature history of any user.

Encrypt/decrypt any PGP message or file with minimal effort.

Supports public key encryption.

Securely store personal files that only you can access.

Share files securely and privately with other users, a group of users, or a team.

250GB of free storage for privately-encrypted files.

Host a public static website for free. Sites are automatically viewable via keybase.pub if an index.html or index.md exist in your public files.

Teams are E2E encrypted, unlike Slack and other services.