fastapi-debugbar

A modern, lightweight debug toolbar for FastAPI — inspired by Django Debug Toolbar, but built for async-first FastAPI apps.

Features

• Real-time request/response inspection
• SQLAlchemy query counting & timing (async + sync)
• Total execution time & endpoint resolution
• Developer-only by default (safe for production)
• Easy plugin system to add custom panels

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Installation

pip install fastapi-debugbar

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Quickstart

from fastapi import FastAPI
from fastapi_debugbar import DebugBarMiddleware

app = FastAPI()
app.add_middleware(DebugBarMiddleware)

@app.get("/")
async def hello():
    return {"message": "DebugBar active!"}

Then open your app in the browser — you’ll see a debug toolbar overlay for each request (only in dev mode).

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Why fastapi-debugbar?

FastAPI lacks a built-in debug toolbar. Existing options are outdated or lack modern async support.

fastapi-debugbar — the modern, async-safe, plugin-based debug toolbar for FastAPI. Designed for SQLAlchemy 2.x and real-world dev/prod safety.

This library provides:

• Async-first design for FastAPI ≥0.100
• Extensible panels: add your own metrics easily
• Production-safe toggle (auto-disabled outside dev)

1. Async-first & context-safe

• Use contextvars for per-request storage → safe for async & background tasks.
• No global state pollution.

2. Modern SQLAlchemy 2.x ready

• Out-of-the-box support for SQLAlchemy 2.x event system (before_cursor_execute / after_cursor_execute for both sync & async).
• Clear roadmap for Tortoise ORM, asyncpg, or others.

3. Plugin-first architecture

• Define a simple panel interface so devs can write:

  class MyPanel(BasePanel):
      async def on_request_start(self, request): ...
      async def on_request_end(self, request, response): ...

  and add it without forking.

4. Production-safe by default

• Only enabled when DEBUG=true or X-Debug-Token present.
• Redacts sensitive headers (e.g., Authorization, Cookies).
• Body capture is size-limited to prevent leaks.

5. Modern packaging & CI

• Uses pyproject.toml (PEP 621) from day one.
• Ships with GitHub Actions CI + PyPI Trusted Publishing.
• Type hints, Black, Ruff/Flake8 pre-commit hooks.

6. Better DX (developer experience)

• Clear, beautiful docs with real FastAPI examples (SQLAlchemy, ORM, no-ORM).
• JSON & HTML modes: developers can choose overlay or debug endpoint.
• Quickstart in 3 lines.

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Roadmap

• Request/response panel
• SQLAlchemy panel
• Template rendering panel
• Profiler panel
• Cache hit/miss panel

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License

MIT

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