nhttp3 — HTTP/3 in Rust

// modules

8 crates, one stack

nhttp3-quic

QUIC Transport

Packets, frames, TLS 1.3 via rustls, streams, flow control, loss detection, NewReno + CUBIC + BBR, QLOG, endpoint I/O loop.

nhttp3-h3

HTTP/3 Protocol

Frame codec, pseudo-header validation, HTTP crate types, error codes per RFC 9114.

nhttp3-qpack

QPACK Compression

Static table (99 entries), dynamic table, encoder/decoder. 50% compression on realistic headers.

nhttp3-python

Python Bindings

PyO3 + custom async bridge. No pyo3-asyncio. Tokio runtime on background thread.

nhttp3-wasm

WASM Target

wasm-bindgen. Browser via WebTransport, non-browser via raw UDP.

nhttp3-ffi

C FFI Layer

Opaque handles, callback-based async, error codes. Runtime managed internally.

// performance

Benchmarks: HTTP/3 vs HTTP/2

HTTP/3 (nhttp3) HTTP/2

TLS Handshake

HTTP/3 QUIC+TLS

1-RTT

154 µs

HTTP/2 TCP+TLS

2-RTT

166 µs

In-process TLS. Over a real network, HTTP/3 saves a full RTT.

Codec Throughput

STREAM frame 1200B

18.7 GB/s

64 ns

STREAM parse 1200B

16.4 GB/s

73 ns

QPACK encode 6h

680 ns

VarInt encode

20 ns

Header Compression

Raw (10 headers)

334 bytes

334 B

QPACK compressed

50% smaller

167 B

// compliance

7 RFCs implemented

RFC	Title	Status
9000	QUIC Transport	ACTIVE
9001	Using TLS to Secure QUIC	ACTIVE
9002	Loss Detection + Congestion Control	ACTIVE
9114	HTTP/3	ACTIVE
9204	QPACK Header Compression	ACTIVE
9218	Extensible Priorities	ACTIVE
9221	QUIC Datagrams	ACTIVE

// hardening

Security audited

Reviewed against 200+ issues from aioquic + quiche. Zero unsafe blocks.

ACK RANGE LIMITCapped at 256 — DoS prevention

FRAME SIZE LIMIT16MB max payload per frame

PACKET VALIDATIONInitial ≥ 1200 bytes enforced

CRYPTO BUFFER128KB cap prevents OOM

STATELESS RESETConstant-time token validation

CID ENTROPYMixed entropy, collision-resistant

IDLE TIMEOUTmin(local, remote) per RFC

MUTEX SAFETYGraceful poisoned-lock handling

// integrations

Drop-in for any framework

Python / FastAPI

Native ASGI Server

nhttp3.serve(app, port=4433)
No uvicorn. No proxy. Rust QUIC server calls your ASGI app directly via PyO3. Proven with FastAPI.

Node.js

Native Addon

serve(4433, handler)
napi-rs addon with embedded quinn. JS callback for each request. QPACK compression included.

Rust

Server + Client

HTTP/3 server with demo + proxy modes. Client with verbose timing. Native QUIC inference server for token streaming.

Any HTTP Server

Reverse Proxy

--proxy http://localhost:8000
Put HTTP/3 in front of Express, Django, Rails, anything. Helps remote clients (saves 2.5 RTTs).

// clients

Connecting to nhttp3

Client	How	Docs
nhttp3-client	Built-in Rust client with timing and verbose output	`cargo run -p nhttp3-server --bin nhttp3-client -- URL`
curl	curl 7.88+ with `--http3` flag. Parallel with `--parallel`	curl guide
Browser	Auto-negotiates via Alt-Svc. Standard `fetch()` works. WebTransport for streams.	browser guide · live demo
Python	`conn = await ep.connect("host", 443)`	python guide

All clients connect to any nhttp3 server (Python, Node.js, or Rust). The protocol is standard HTTP/3 — any HTTP/3 client works.

// structure

Architecture

                    +-------------------+
                    |    Application    |
                    +--------+----------+
                             |
                    +--------v----------+
                    |     nhttp3-h3     |  HTTP/3 frames, headers
                    +--------+----------+
                             |
              +--------------+--------------+
              |              |              |
     +--------v--------+    |    +---------v--------+
     |   nhttp3-qpack  |    |    |    Extensions    |
     |   QPACK codec   |    |    |  Datagram / Prio |
     +-----------------+    |    +------------------+
                             |
                    +--------v----------+
                    |    nhttp3-quic    |  Endpoint, TLS, streams
                    |                   |  loss, congestion, QLOG
                    +--------+----------+
                             |
                    +--------v----------+
                    |    nhttp3-core    |  VarInt, CID, errors
                    +-------------------+

// examples

Code examples

Example	What	Links
Python	nhttp3.serve(app) — native ASGI, no uvicorn (tested, working)	guide · example · source
Node.js	serve(port, handler) — native addon via napi-rs (tested, working)	guide · source
Rust Server	HTTP/3 server + client + benchmarks (5 e2e tests, 0.12s)	source
Browser	Fetch API, WebTransport, SSE streaming client	live demo · source
curl	curl --http3 reference: streaming, parallel, timing	guide · reference
Reverse Proxy	--proxy http://localhost:8000 (for any existing HTTP server)	guide