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Truncating large member lists December 1, 2017

Updated: 2018-03-06 APIs

Arrays of members found in API methods will become truncated beginning December 1, 2017.

The maximum number of results found in members continues to decrease regularly. As of March 2018, the limit is set to 500 results. Use conversations.members for channels with large memberships.

Initially, Slack will limit members to the first 1,500 users and then gradually lower the number of users returned. You should expect these methods will cease returning members entirely at some point in the future. If you rely on the members array returned by any of the following methods, you should instead begin using conversations.members for a full list of members:

As Slack teams continue to grow in size, returning the full members array in these methods is no longer practical or performant, for the Slack APIs or developers. The conversations.members method will allow you to request a list of members at a time that makes sense for your app and should keep these method calls nice and zippy.

What's changing?

Previously, calling a method like rtm.start or would include a members array that listed all of the members of a workspace or channel. But some Slack workspaces and channels now have tens of thousands of team members, which means these methods can be slow to be delivered and difficult for developers to manage.

Starting December 1, 2017, we will begin truncating the members array to 1,500 members. This number will then be lowered over time until, eventually, the members array will cease to be returned in these methods.

At the time of the last update in March 2018, members results are capped at 500.

If any members array is truncated, you'll receive a member_list_truncated warning in the response's response_metadata:

    // all other parts of the response
    "response_metadata": {
        "warnings": [

If you need a list of team members in a channel, please begin using the recently introduced conversations.members method, which includes a pagination cursor. See pagination for more detail.

What isn't changing?

The, channels.join, channels.list, and rtm.start methods will otherwise continue to function as always, just without a reliably complete members array.

What happens if I do nothing?

If your app isn't using the members array returned by any of the above methods, you don't need to change a thing!

If your app relies on the members array returned by these methods, it will no longer reliably return a full list of team members starting December 1, 2017. You should begin using the conversations.members method to get a complete list of team members.

When is this happening?

The members array will be truncated starting December 1, 2017.

As of March, 2018 the members array is capped at 500 and will continue to decline.

Please contact us if you have any concerns at

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