Delete your free Slack backlogs!

Why delete Slack backlogs?

Slack and other chat software tend to retain conversation history so that you can see and search what was said in the past. This can be very helpful for historical context and avoiding repeat conversations, but there’s all kinds of reasons why you don’t want to retain backlogs indefinitely:

  • people who join some time after the Slack is formed may find themselves being discussed in backlogs in terms that are uncomfortable now they can see it
  • the relationships of people in the Slack may change over time and previously friendly conversations may be weaponised by members
  • any malicious person who gains access to your Slack (whether by hacking or by being invited) gets the entire history of everything said there to bully or blackmail people with
  • the contents of the Slack might be subject to legal discovery at some point in the future and be used to win a lawsuit against members or owners of the Slack, or else simply dumped into the public record

Learn more in the Electronic Frontier Foundation’s Slack privacy campaign: What if All Your Slack Chats Were Leaked?, Slack should give free accounts control over retention.

How to delete Slack backlogs.

If you pay for Slack, you should use their message and file retention feature.

If you have a free Slack, you can do it yourself. If you are using the free plan, you can delete messages through the API. Here’s a really simple sample Python script any admin of your Slack can use, which will delete most messages posted more than 6 weeks ago. (Instructions.)

Alternatively, slack_cleaner2 is nicely flexible if you want to develop your own script. Or members could delete at least their own messages with eg the Message deleter for Slack 2.0 Chrome extension.

Script caveats

You will need owner or administrator access to your Slack instance (or else you cannot delete messages other users wrote).

The script operates with the credentials of the admin who runs it, and will not be able to delete other people’s messages in 1:1 DMs, or any messages in any private channel that admin is not in.

The script will not delete messages older than the 10,000 recent messages that free Slacks have access to (even deleting the newer messages doesn’t restore access to these). Yet these older messages are retained by the company and could be accessed if, eg, someone pays for the Slack in future or if a discovery motion is granted. Unfortunately, you will need to pay for Slack, at least briefly, to access these older messages for deletion.

Creative Commons License
Delete your free Slack backlogs! by Mary Gardiner is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

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