1. Any channel ID
Open the slack webpage (http://yourteam.slack.com) and then simply open the channel. The channel ID is displayed in the browser URL
Here is the easiest way to manually find the slack IDs
2. Any user ID
To find a user ID you need to open your browser dev-tools console and inspect the user-link in the sidebar. The user ID can be found in the HTML attribute "data-member-id"
In Slack: (1) Click on the users name and choose (2) "Show Profile". Then open the "..." menu and you see the option (3) "Copy Member-ID ..." - to get your own user ID via the UI, you have to click the Team-Logo in top-left corner and then choose "Profile & Account"
3. Team ID
Simply open the dev-tools of your browser, switch to the "Console" tab and enter the text
boot_data.team_id into the console. This will display your team ID
Still need help? Please review this quick video: