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

python -m pip install relay-backend==0.0.1

from fastapi import FastAPI
from relay_agent import install_relay

app = FastAPI()
install_relay(app)

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

Run your backend normally, for example uvicorn main:app --reload, then visit http://localhost:8000/relay/.

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 and realtime team sync are outside v0.0.1.

The PyPI distribution is relay-backend; the Python import remains relay_agent. 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.