Open Source Alternatives to Slack

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  Mattermost

  28.0k·Apache-2.0

  2 feats

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  Element

  10.0k·Apache-2.0

  2 feats

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  Rocket.Chat

  42.8k·MIT

  2 feats

• C

  Chatto

  2.3k·AGPL-3.0-or-later (Apache-2.0 exceptions)

  8 feats

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  Zulip

  25.8k·Apache-2.0

  8 feats