Here you can use your own data from your Slack organization(s). How:

1. Open Slack in Google Chrome
2. Right click > Inspect
3. Click Network
4. Type "users/list" on the Filter
5. Refresh the page (F5 or CTRL+R or CMD+R
6. Click on the filtered item, go to Preview tab
7. Right click on the "results" > Copy value, paste here and press Save