To import your current Slack data into Rocket.Chat:
- Go to
https://[your_app].slack.com/services/export
- Click on Start Export
- Wait until your download is ready and download it (it will be a .zip file)
- Go to
https://[your_rocketchat]/admin/import/prepare/slack
- Choose your downloaded .zip file and wait until Rocket.Chat can read it (it can take a few minutes, depending on the size of your Slack export)
- Deselect any items you don’t want to import
- At the top of the page, click on Start Importing
Source: Slack import