Backlot MCP server

Backlot

Run enterprise SaaS APIs locally.

Backlot is a local emulator for Slack, Gmail, Google Drive, GitHub, Jira, Notion, S3 and other enterprise APIs. It reproduces the response shapes, pagination, authentication, errors and per-document access controls an integration has to handle, over a deterministic corpus you control — so you build and test against the official vendor SDKs with no vendor account, no OAuth approval, no secrets in CI and no network.

Try it in 60 seconds

pip install backlot
backlot import --bundled   # a corpus ships with the package; nothing to fetch or write
backlot serve              # every supported API, at http://127.0.0.1:8000

Point an official SDK at it by changing one base URL:

from slack_sdk import WebClient  # pip install slack_sdk

slack = WebClient(token="admin-service-token", base_url="http://127.0.0.1:8000/slack/api/")
print(slack.conversations_list()["channels"])

The same call targets Slack in production and Backlot in development. Backlot supplies the data and the credentials; your code keeps the vendor's request and response contract.

A test can run its own server instead, on a free port, with nothing to start or clean up:

import backlot
from slack_sdk import WebClient

with backlot.serve() as s:  # no arguments: a tiny hello-world corpus
    slack = WebClient(token=s.token, base_url=f"{s.base_url}/slack/api/")
    channels = slack.conversations_list()["channels"]

Let your coding agent run Backlot instantly

This repo is its own plugin marketplace, so the agent skill installs with no clone and no pip install first. Or hand the agent every source as MCP tools: backlot mcp starts a server if none is running and serves them all over stdio, with --user answering as that person.

claude plugin marketplace add brekkylab/backlot && claude plugin install backlot@brekkylab
codex plugin marketplace add brekkylab/backlot && codex plugin add backlot@brekkylab
pip install "backlot[mcp]" && claude mcp add backlot -- backlot mcp   # every source as MCP tools

and prompt like this:

Mock our Slack workspace with three messages in an #incidents channel, get a server running, then show me what conversations.history actually returns for that channel.

Why not use mocks?

A hand-written mock returns the response your code already expects. Backlot implements the other side of the integration, so it exposes the assumptions a mock would repeat — it is for when the behavior of the API, not just the contents of one response, is what you need to test.

Shortened. The full README is on GitHub.