slack

Slack API Emulator

Fully stateful Slack Web API emulation with channels, messages, threads, reactions, user profiles, presence, modern file uploads, pins, bookmarks, views, OAuth v2, and incoming webhooks. Chat writes preserve common rich message fields such as blocks, attachments, metadata, formatting flags, unfurl flags, and client message ids. Conversation writes update archive state, names, topics, purposes, membership, DMs, MPIMs, and read cursors. User writes update profile fields, status, custom fields, and deterministic active or away presence. File writes support the current external upload flow with local upload URLs, file share messages, reads, lists, downloads, and deletes. Pin and bookmark writes support channel message pins and link bookmarks. View writes support App Home publishing and modal stacks. Seeded OAuth apps and OAuth installs create bot users and installation records. OAuth exchanges and explicit token seeds create scoped token records. State changes dispatch event_callback payloads to configured webhook URLs.

Start

# Slack only
npx emulate --service slack

# Default port (when run alone)
# http://localhost:4000

Or programmatically:

import { createEmulator } from 'emulate'

const slack = await createEmulator({ service: 'slack', port: 4003 })
// slack.url === 'http://localhost:4003'

Auth

Pass tokens as Authorization: Bearer <token>. All Web API endpoints require authentication.

curl -X POST http://localhost:4003/api/auth.test \
  -H "Authorization: Bearer test_token_admin"

Requests without a token return not_authed. In relaxed scope mode, any non-empty unknown bearer token maps to the first seeded user.

Scope checks are relaxed by default for local development. Set slack.strict_scopes: true in seed config when you need supported Web API methods to return Slack-style missing_scope errors with needed and provided fields. Strict mode checks chat:write, channels:read, channels:history, channels:join, channels:manage, channels:write, groups:read, groups:history, groups:write, im:read, im:history, im:write, mpim:read, mpim:history, mpim:write, users:read, users:read.email, users.profile:read, users.profile:write, users:write, files:read, files:write, pins:read, pins:write, bookmarks:read, bookmarks:write, reactions:read, reactions:write, and team:read. Slack lists no method-specific scopes for views.publish, views.open, views.update, or views.push, so the emulator requires auth but does not add strict-scope checks for those methods.