fastapi-standalone-di

Use FastAPI's dependency injection outside of any web/ASGI context.

FastAPI ships a powerful dependency injection system — Depends, sub-dependencies, yield teardown, per-resolution caching — but it is tightly coupled to the request/response cycle. fastapi-standalone-di reuses that exact machinery so you can resolve and invoke your dependencies from plain Python: CLI scripts, workers, cron jobs, tests — no HTTP server required.

Install

pip install fastapi-standalone-di
# or
uv add fastapi-standalone-di

Usage

Resolve any callable that uses Depends(), exactly as FastAPI would:

import asyncio

from fastapi import Depends

from fastapi_standalone_di import FastAPIContainer


def get_settings() -> dict[str, str]:
    return {"db_url": "postgres://localhost/app"}


class Database:
    def __init__(self, settings: dict[str, str] = Depends(get_settings)) -> None:
        self.url = settings["db_url"]


async def main() -> None:
    async with FastAPIContainer() as container:
        db = await container.get(Database)
        print(db.url)  # postgres://localhost/app


asyncio.run(main())

Sub-dependencies, yield teardown, caching, scopes, dependency overrides, registrable interfaces, per-package binding discovery, shared app state, application-lifetime singletons, standalone Request/Response stubs, and query/path/header/cookie parameters are all covered in the documentation.

Documentation

Full documentation is available at toilal.github.io/fastapi-standalone-di. The in-development docs (built from develop) are previewed at toilal.github.io/fastapi-standalone-di/dev/.

Requirements

• Python ≥ 3.11
• FastAPI ≥ 0.61

License

MIT © Rémi Alvergnat

CHANGELOG

v0.7.0 (2026-07-09)

Bug Fixes

• Detect cyclic dependency resolution instead of deadlocking (#50, 90d3e06)

Features

• Discover @singleton implementations in auto_bindings (#48, 9468319)

v0.6.0 (2026-07-08)

Features

• Auto_bindings() to wire interfaces to implementations by convention (#46, c7705de)

• Auto_bindings() — wire interfaces to implementations by convention (#46, c7705de)

v0.5.1 (2026-07-08)

Bug Fixes

• Bind the passed package's own module in register_bindings (#44, 8ee830f)

• Wire a package's own binding module in register_bindings (#44, 8ee830f)

v0.5.0 (2026-07-08)

Features

• Make lazy singletons usable as ASGI route dependencies (#42, bebe3e8)

v0.4.1 (2026-07-08)

Bug Fixes

• Patch fastapi.params.Depends in place for registrable support (#40) (#41, 08927a5)

v0.4.0 (2026-07-08)

Features

• AppState-backed application singletons (ASGI + standalone) (#39, a87d11f)

v0.3.0 (2026-07-07)

Features

• Discover per-package di.py modules to auto-register bindings (#37, 02fc05b)

v0.2.0 (2026-07-05)

Features

• Support Python 3.11 (#35, f399c8e)

Changelog entries are generated automatically by python-semantic-release from Conventional Commits on release.