Relay Backend

An offline API testing interface for your FastAPI application. Install one Python package, mount it once, and open /relay on your backend's existing port.

Install

1. Install in your backend's Python environment:

python -m pip install relay-backend

A fresh installation gets the latest stable release. To update an existing installation:

python -m pip install --upgrade relay-backend

Restart the backend after upgrading. The browser title uses your application's name: FastAPI(title="Ludo Portal") becomes Relay - Ludo Portal. Any application's title works.

2. Add these lines where your FastAPI app is created:

from relay_backend import install_relay
install_relay(app)

3. Restart the backend with its usual command and open /relay on its existing port.

from fastapi import FastAPI
from relay_backend import install_relay

app = FastAPI()
install_relay(app)

@app.get("/health", tags=["System"])
def health():
    return {"status": "ok"}

No repository clone, Node installation, frontend build, CDN, separate Relay process, or target URL is required. Existing applications only need the import and install_relay(app) call. Use install_relay(app, enabled=settings.DEBUG) to keep Relay under your application's development flag. Install it on the FastAPI object before wrapping that object in Socket.IO or another ASGI wrapper.

Included

• Code-generated OpenAPI endpoints grouped by tags, with inline request/response testing.
• Shared and per-endpoint bearer, Basic, API-key and explicit no-auth modes.
• Five color schemes, copy controls, response focus, and Relay/JSON endpoint exports.
• Manual endpoint status, defaulting to Done, with optional Git-shared status and inferred source attribution.
• A bundled standalone CLI for local OpenAPI backends and portable .relay reports.

Python 3.11+ is required. This is a local development tool: only loopback hosts/clients are accepted. Request execution invokes your real application middleware, dependencies and handlers. Tests can change your development data. Multipart upload, OAuth browser flows, remote/shared deployment are outside v0.0.4. Opt into automatic team statuses with install_relay(app, sync_status=True) using the backend repository's existing Git remote. Team setup explains access and conflict handling.

Setup and handoff tools in 0.0.4

Run python -m relay_backend init --project ./backend to preview a supported FastAPI integration. Add --apply to write an unambiguous edit; factories and multiple apps receive manual guidance. python -m relay_backend doctor --target http://127.0.0.1:8000 --json checks the local runtime, OpenAPI and native mount with sanitized output. See setup documentation.

Endpoints include local Notes & activity, retained unsaved edits and explicit contract-change explanations. Named request examples load only when applied. Git shares statuses, not notes, credentials or request traffic.

The PyPI distribution is relay-backend; the Python import is relay_backend. The former relay_agent root import remains compatible. relay-agent on PyPI is an unrelated package.

Documentation · Source · Issues

Licensed under Apache-2.0. Bundled React, Lucide and JetBrains Mono assets retain their respective licenses; see THIRD_PARTY_NOTICES.md.