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openai
from lihil import Lihil, Route, Stream
from openai import OpenAI
from openai.types.chat import ChatCompletionChunk as Chunk
from openai.types.chat import ChatCompletionUserMessageParam as MessageIn


gpt = Route("/gpt", deps=[OpenAPI])


def message_encoder(chunk: Any) -> bytes:
    if not chunk.choices:
        return b""
    return chunk.choices[0].delta.content.encode() or b""


@gpt.sub("/messages").post(encoder=message_encoder)
async def add_new_message(
    client: OpenAPI, question: MessageIn, model: str
) -> Stream[Chunk]:
    async for chunk in client.responses.create(
      messages=[question], model=model, stream=True
    ):
        yield chunk

50%-100%

Faster than other ASGI frameworks, more for larger app.benchmarks

100%

Test Covered and strictly typed

> 45K

RPS(per CPU thread)

Get Started in Seconds

Lihil is designed for simplicity without sacrificing power. Install with pip and start building your next Python web application.

$|
Install

Create a REST API in minutes

app.py
from lihil import Lihil, HTTPException, Struct, Route, Param, Annotated, Empty


class TodoItem(Struct):
    id: int
    title: str
    completed: bool = False


todo = Route("/todos", deps=[TodoRepo])


@todo.get
async def get_todos(todo_repo: TodoRepo, n: Annotated[int, Param(lt=100)]):
    return await todo_repo.list_todos()


@todo.post
async def create_todo(item: TodoItem, todo_repo: TodoRepo) -> Annotated[Empty, 201]:
    await todo_repo.add(item)


if __name__ == "__main__":
    lhl = Lihil(todo)
    lhl.run(__file__)

Why Choose lihil?

A clean, powerful Python web framework built for modern apps.
Param Parsing & Validation

Automatically parse & validate request data from path, query, headers, and body with msgspec – 12x faster and 25x more memory efficient than Pydantic.

Powerful Dependency Injection

Inject dependencies based on type hints. Supports factories, async, scopes, and singletons – all lightning fast.

WebSocket

Handle WebSocket connections with clean, type-safe APIs. Easily test using the built-in WebSocket test client.

OpenAPI & Error Docs

Auto-generate OpenAPI docs and problem details. Custom exceptions are turned into clear API responses.

Authentication & Authorization

Built-in support for JWT and OAuth2. Auth objects are type-safe and serializable.

Message System

Built-in event system to publish and handle events, both in-process and out-of-process, efficiently.

Great Testability

Built-in test client for endpoints, routes, and middlewares – no extra setup required.

Memory efficient

Optimized for minimal memory usage. GC overhead is reduced, making services more stable under load.

AI-Ready

Designed with AI in mind. Built-in support for SSE, MCP, and remote handlers coming soon.

Join the Community

Lihil is backed by a growing community of Python developers. Get support, contribute, and help shape the future of fast Python web development.

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Latest Release

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Join the growing community of developers using Lihil to build fast, robust, and scalable web applications.

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