The channels where the story gets discussed.

The Slack Web API — conversations, threads, reactions, and the workspace roster — for a simulated org whose chatter reconciles with everything else it does: the #incident-bridge burst brackets a real tracker incident, review threads echo real PRs, and release announcements cite tags you can fetch from the git hosts.

Coverage, hosts and pinned snapshots for Slack — 16 of 17 read surfaces served and verified.

01Point your client at slack.

02Read channels, history, threads

03Pin a snapshot for CI

01 / Base URL + auth

One workspace, any token.

Point requests at https://slack.sandboxapis.dev. Paths are Slack's method-RPC grammar — /api/<method>, exactly like slack.com/api — and the error model is Slack's own inversion: success and failure are HTTP 200, split by the body's ok boolean (the only real HTTP status in the dialect is the rate-limit 429 + Retry-After). Auth is a bot or user token (xoxb-…/xoxp-…) in the Bearer slot; any value passes here — no app to create, no scopes to request, no install flow.

request.sh

curl -H 'Authorization: Bearer xoxb-anything' \
  "https://slack.sandboxapis.dev/api/conversations.list"

Using a key? Keys & rate limits → — a SandboxAPIs key rides the same Bearer slot and lifts the anonymous limit.

@slack/web-api works unchanged.

The official SDK takes a custom endpoint via its slackApiUrl option — the one line you change. Its form-encoded POSTs, cursor paginator, and typed platform errors all run against this host exactly as against slack.com, and the drop-in smoke in our conformance suite proves it on every build. See what's covered →

javascript

import { WebClient } from "@slack/web-api";

const slack = new WebClient("xoxb-any-token", {
  slackApiUrl: "https://slack.sandboxapis.dev/api/",
});

const { channels } = await slack.conversations.list();

02 / The reads that matter

Channels, history, threads, people.

report.sh

# The workspace's channels — one per team, plus #incident-bridge,
# #releases, and #agora (the org-wide square)
curl -H 'Authorization: Bearer xoxb-anything' "https://slack.sandboxapis.dev/api/conversations.list"

# A channel's history (newest first, cursor-paginated, top-level only)
curl -H 'Authorization: Bearer xoxb-anything' \
  "https://slack.sandboxapis.dev/api/conversations.history?channel=CHANNEL_ID"

# A thread: the parent message first, then its replies
curl -H 'Authorization: Bearer xoxb-anything' \
  "https://slack.sandboxapis.dev/api/conversations.replies?channel=CHANNEL_ID&ts=PARENT_TS"

# The roster — emails join against the AI-telemetry hosts' rosters
curl -H 'Authorization: Bearer xoxb-anything' "https://slack.sandboxapis.dev/api/users.list"

03 / A real response

Live from #incident-bridge.

200 · application/json

{
  "ok": true,
  "messages": [
    {
      "type": "message",
      "user": "U127GRU2DLG",
      "text": "schema marks a nullable field as required. paging whoever's closest to the logger.",
      "ts": "1781455608.003359",
      "team": "T3WXAQR47CB",
      "thread_ts": "1781455608.003359",
      "reply_count": 15,
      "reply_users": [
        "UNDH9MROOV9",
        "UZ4CH940GQH",
        "UOEW4UQN3I4",
        "UM7D2RMLWY1",
        "UJ4C66GKFQ6",
        "U7YS3B38974",
        "U127GRU2DLG",
        "U592EZ56KGE",
        "UMSMHBBLH8H",
        "UQE80ZXP3UZ"
      ],
      "reply_users_count": 10,
      "latest_reply": "1781636928.664201",
      "is_locked": false,
      "subscribed": false
    }
  ],
  "has_more": false,
  "pin_count": 0,
  "response_metadata": {
    "next_cursor": ""
  }
}

04 / Pin a snapshot

Deterministic CI.

The *.snap. base URL is byte-identical on every request — every ts, every thread, every reaction frozen — a messaging fixture that never moves under your tests.

.env

# reproducible in CI
export SLACK_API_URL=https://slack-2026-08.snap.sandboxapis.dev/api/

Tour the universe → · Coverage manifest → · Versioning & pinning →