hayate

Hayate ecosystem: Start here · Production golden app · Tested compatibility

A web-standards-first Python web framework, inspired by Hono.

hayate (疾風, "swift wind") brings the Fetch API model to Python. Everything you touch maps 1:1 to WHATWG / IETF web standards; Python-local protocols such as WSGI and ASGI are demoted to adapter-level implementation details.

• Standards-first — Request / Response / Headers / URL follow WHATWG Fetch and URL semantics. Routing syntax is the WHATWG URLPattern standard (/books/:id), not a custom DSL.
• Minimal, portable core — one pure-Python Unicode standards dependency; runs anywhere CPython or Pyodide runs.
• Runtime-agnostic — the app core is a pure fetch(Request) -> Response function. ASGI servers, Cloudflare Python Workers, and AWS Lambda are thin adapters.
• Resource-bounded uploads — Fetch-shaped FormData/File parsing has explicit body/part/header limits; native ASGI spills large files to disk while Workers remains bounded and disk-free.
• Async-first, typed — Python 3.12+.

Install

uv add hayate        # or: pip install hayate

Quickstart

from hayate import Hayate, HTTPException

app = Hayate()

@app.get("/books/:id")
async def show_book(c):
    book = BOOKS.get(c.req.param("id"))
    if book is None:
        raise HTTPException(404, title="Book not found")
    return c.json(book)

Run with any ASGI server:

uvicorn main:app

On ASGI, ASGIPathDispatcher can retain Django admin/ORM or existing FastAPI endpoints under explicit prefixes while new routes use Hayate. Cloudflare Workers continues to use Hayate's direct Fetch adapter with no ASGI detour. See the runtime guide.

Testing without a server

The app core performs no I/O, so tests call it directly — no test client, no sockets:

async def test_show_book():
    res = await app.request("/books/1")
    assert res.status == 200
    assert (await res.json())["id"] == "1"

Runtime-bound CORS allowlists can inspect the request context:

from hayate.middleware import cors

app = Hayate(env={"CORS_ORIGINS": {"https://app.example.com"}})

def allowed_origin(c, request_origin):
    return request_origin if request_origin in c.env["CORS_ORIGINS"] else None

app.use(cors(origin_resolver=allowed_origin, credentials=True))

Conformance and performance, measured

• Standards conformance runs against vendored web-platform-tests vectors on every pytest run, with ratcheted pass counts — see docs/conformance.md.
• A locked, end-to-end benchmark measures the same workload against FastAPI, Django, and Hono across startup, dependencies, deployment payload, cold start, throughput, and an HTTP contract. Framework-only ASGI overhead is also benchmarked against Starlette — see docs/benchmarks.md.
• A dated, source-backed capability matrix separates Hayate's portable agent/API advantage from Django's full-stack advantage and Hono's JavaScript-edge advantage without inventing a universal score.
• Every core change is tested against the public auth, fetch, MCP, OpenAPI, and generated Workers heads using the exact unpublished wheel — see docs/ecosystem-compatibility.md.

Status

Alpha (0.12.x): the surface tracks DESIGN.md (Japanese) and may still move before 1.0. Changes are recorded in CHANGELOG.md; platform research lives in docs/research/.

The wider ecosystem adds authentication, MCP, OpenAPI, and a portable client-side fetch. See the hayatepy organization profile for the current compatibility matrix.

License

MIT