This article catalogs the Slack Web API endpoints the iPaaS.com Slack integration calls at runtime. It is intended as a reference for firewall allow-listing, OAuth scope configuration, troubleshooting, and understanding the data flow between iPaaS.com and Slack. Subscribers or their MiSP do not call these endpoints directly; iPaaS.com calls them on the subscriber's behalf when an alert is dispatched.

Slack exposes a JSON-over-HTTP Web API. The integration uses a single base URL for both the Test and Production environments.

All endpoint paths below are shown relative to this base URL, written as [Base URL]/method.name.

The Slack Web API authenticates every request with a bearer token. iPaaS.com supplies the token on the Authorization request header as Bearer <token>.

The token is established during installation by one of two supported methods:

In both cases the message-sending and user-lookup requests carry the bearer token. The token grants the chat:write scope (used to post messages) and the users:read scope (used to read the workspace member list). For details on obtaining and storing the token, see the Slack Connections and Settings and Slack Installation Instructions articles linked below.

Posts an alert message to the resolved Slack member. iPaaS.com supplies the destination Channel (the resolved member id) and the message Text, formatted as one or more Block Kit section blocks. A long message body is split across blocks and, when split, a follow-up notice is appended.

Slack applies special rate limiting to this method: it generally allows an app to post one message per second to a specific channel, with a workspace-wide ceiling above that of several hundred messages per minute.

Retrieves the workspace member list. The integration uses this list to resolve the Channel mapping value — a Slack profile name (Name, then Real Name) — to the underlying Slack member id before posting the message. If no member matches the supplied name, the alert is not delivered to a recipient.

Pagination: users.list returns results using cursor-based pagination. Each response includes a response_metadata.next_cursor value; supplying that value as the cursor argument on a subsequent request, together with a limit, retrieves the next page. Supplying no limit causes Slack to attempt to return the entire member set in one response.

When a subscriber authorizes the iPaaS.com Slack app under the OAuth 2.0 method, iPaaS.com exchanges the authorization code Slack returns for a stored access token using this endpoint. The exchange supplies the client credentials and the redirect URL that iPaaS.com registered for the environment; the subscriber does not enter these values. This endpoint is called only during authorization, not during normal alert dispatch.

Slack publishes per-method rate limits. The limits relevant to this integration, as documented by Slack (retrieved 26 June 2026), are:

Independently of Slack's limits, the subscription carries an API Throttle Limit / Concurrent Batch Executions setting that governs how many batches iPaaS.com runs at once (Initial 5, Ongoing 500). Subscribers or their MiSP should keep this in mind when dispatching high volumes of alerts so that Slack's per-channel limit is not exceeded.