Slack has raised our charges by $195k per year

Hey! I have an open-source project for browsing an exported slack archive, it may be useful to you so you can see and search the history: https://github.com/pkarolyi/slack-archive-browser

I haven’t maintained it in a while since it works for us, but PRs are welcome :)

A good first one would be adding non-slack authentication as currently it only supports Slack openid for logging in, but it uses next-auth and should be simple to extend

Mattermost also has a tutorial to import your slack messages

https://docs.mattermost.com/administration-guide/onboard/mig...

From one walled garden to another?