Slack Member ID: Where to Copy It, and What the U Means

A Slack member ID is the code Slack uses for a person, such as U0B7L4YK420. To copy yours, click your profile picture, choose Profile, click the three-dot More button and pick Copy member ID. For someone else, open their profile the same way (click their name in a message). Slack calls it a member ID in the app and a user ID in the API; they are the same value. We checked the menu, the API calls and the ID formats below on 29 September 2026.

Copy a member ID from a profile

• Click a person's name or picture, or your own picture at the bottom left and then Profile.
• In the profile panel, click the three-dot More button at the end of the button row.
• Click Copy member ID.

We saw no confirmation message after clicking, but the clipboard held the ID: pasting gave U0B7L4YK420.

What a Slack user ID looks like

Every human ID we saw starts with U and has 11 characters:

Where	Users	Starting letter	Length
A 3-person Slack workspace, all members listed with users.list	3	U	11, except USLACKBOT (9)
A second workspace, 11 members	11	U	10 IDs of 11 characters, USLACKBOT of 9

Slack's docs say user IDs can also start with W, which Enterprise Grid org-wide accounts use, and that the length may grow. Neither of our workspaces is on Enterprise Grid, so we saw no W. Match IDs with a pattern such as ^[UW][A-Z0-9]{8,}$ rather than a fixed length.

A bot has three IDs, and only one of them goes in a mention. Our test bot's user ID was U0C61H3JW5N, its bot ID B0C52236M9B, and its app ID A0C572AF69Y. users.info on the user ID returned "is_bot": true plus the other two in its profile.

Get the ID, or the name, with the API

users.info turns an ID into a person. It needs the users:read scope:

curl -s https://slack.com/api/users.info \
  -H "Authorization: Bearer $SLACK_BOT_TOKEN" -d user=U0B7L4YK420

The fields that answer "slack user id to name", from our response:

{"id": "U0B7L4YK420", "team_id": "T0B7JBCDKC1", "name": "sieun", "real_name": "sieun", "tz": "Asia/Seoul", "is_admin": true, "is_owner": true, "is_bot": false, "deleted": false}

Things that did not work:

To list everyone, users.list returns every member with id, name and is_bot. It pages at up to 200 per call through response_metadata.next_cursor.

Use the ID in a mention

Wrap the ID in <@...> and Slack shows the person's current name. Without the brackets it stays plain text. We posted this to a DM:

The mention keeps working after a person changes their display name, which is why bots store IDs instead of names. Mentions from webhooks, user groups and @here are covered in how to mention a user in a Slack webhook. If you want a date that shows in each reader's own time zone next to a mention, the Slack timestamp generator builds the <!date> code.

FAQ

Is the member ID the same in every workspace? No. The account we tested with is signed in to three workspaces and has three IDs: U0APM2X5V99, U0B7L4YK420 and U0B7A85MCM9.

Can someone see my email from my member ID? Not through the API without users:read.email. Our bot with users:read got name, time zone and admin flags from users.info; the profile in the response had no email field. A person can still see an email on a profile if its owner shows it.

Where is the workspace ID? It is the T... value, team_id in users.info and auth.test. Channel IDs start with C, and the channel ID sits at the bottom of the channel details; see channel_not_found for where.