1. Run it
On Slack, run /isdown <service> or /realuptime isdown <service>, for example /isdown openai or /realuptime isdown stripe. On Discord, run /isdown service:<name>, for example /isdown service:cloudflare. The answer is the same reading the public outage page for that vendor shows: whether our checks pass or fail, or awaiting data if nothing has been checked yet, plus a link to the full page. A vendor RealUptime does not track answers honestly with "does not currently track", never a guess. A query that could mean more than one tracked vendor lists the candidates instead of picking one.
2. On Slack: add the app once
Under Account settings > Integrations, press Add to Slack. /isdown then works for anyone in that workspace immediately, with no separate step to connect the workspace to a RealUptime account: it answers from the public Outages catalog, not from any account's own data.
3. On Discord: invite the bot to a server
A server admin adds the RealUptime bot with a bot-invite link under Account settings > Integrations (no RealUptime account needed for the server, no OAuth exchange with RealUptime). Once added, /isdown works for anyone in that server. Unlike Slack's ephemeral reply, Discord's /isdown posts to the channel: it is a public fact, not private account data.
Go deeper
The full reference lives in the docs: API documentation. Error codes named above are each explained in the error-code reference.