Skip to content

async · ASGI-native · typed · MCP-native

Veloce — Async Python Web Framework

One route definition is an HTTP endpoint, an OpenAPI operation and an MCP tool. Routing, typed dependency injection, WebSockets, templating, sessions and a built-in test client — all in one tree, no second service to keep in sync.

Get started API reference

Python 3.10+ MIT licensed MCP built in pip install veloceframework

Veloce framework (PyPI: veloceframework) is an ASGI-native, async-first Python web framework for building APIs and full-stack applications. It draws Flask-compatible patterns (g, flash, blueprints, @app.route) and FastAPI-style typed dependency injection together into one tree — without depending on either. Requires Python 3.10+.

app.py
from veloce import Veloce

app = Veloce()


@app.get("/hello/{name}")
async def hello(name: str):
    return {"hello": name}


if __name__ == "__main__":
    app.run(host="0.0.0.0", port=8000)

Type-annotated path parameters are coerced automatically, dictionaries become JSON responses, and the route is registered on the radix tree at import time.

One flag also serves that handler to an AI agent as an MCP tool:

app.py
from veloce import Veloce

app = Veloce()


@app.get("/users/{user_id}", expose_as_mcp_tool=True,
         mcp_description="Fetch a user by id")
async def get_user(user_id: int):
    return {"id": user_id}

There is no second service and no re-declared schema. An HTTP client calls the endpoint, an agent calls the tool, and both reach the same handler, the same dependencies and the same Security() check — because both doors emit from one route contract instead of a hand-written mirror of it. New here? Why Veloce Exists explains the one-IR architecture the rest of the framework follows from.

Why Veloce

  • Fast by design

    Built on raw asyncio with orjson and httptools. Handler signatures are inspected once at registration — no reflection on the request hot path.

  • Radix-tree routing

    Path parameters are matched and type-coerced during tree traversal, with built-in int, float, uuid, path, and custom converters.

  • Typed dependency injection

    Depends, Security, and SecurityScopes resolve from precompiled plans, including yield-style dependencies with teardown.

  • Batteries included

    OpenAPI 3.1, WebSockets, Server-Sent Events, background tasks, middleware, signed sessions, and signals — all in core.

  • Validated, both ways

    Pydantic v2 validates request bodies; response_model serialises and filters what goes back out.

  • Honest tests

    The in-memory TestClient drives the real ASGI surface — middleware, encoding, and cookies included.

Follow the tutorial