httpx-pycurl

httpx-pycurl provides an httpx transport that executes requests with pycurl. It combines the goodness of curl with the familiar httpx API, including support for http/2 and even non-http protocols built into curl. AsyncPyCurlTransport performs better than httpx's default AsyncHttpTransport with http2=True, taking about 78% of the time to issue 128 requests in parallel. Under heavier usage httpx-pycurl appears to pull further ahead of alternative libraries, without replacing all of httpx; just httpx's transport.

Usage

AsyncPyCurlTransport is the focus of this package. It uses the curl multi_socket interface to integrate curl with the asyncio event loop.

import httpx
from httpx_pycurl import AsyncPyCurlTransport

transport = AsyncPyCurlTransport(timeout=10.0)

async with httpx.AsyncClient(transport=transport) as client:
    responses = await asyncio.gather(*(client.get(url) for url in urls))

AsyncPyCurlTransport delegates SSL/TLS handling to curl and does not use Python's builtin ssl module. By default it calls certifi.where() to set root certificates. It is also possible to pass a custom path to the root certificates with AsyncPyCurlTransport(cainfo=ca_cert_path).

PyCurlTransport is not the focus of this project and is less likely to work. In the future it may delegate to AsyncPyCurlTransport.

import httpx
from httpx_pycurl import PyCurlTransport

transport = PyCurlTransport(timeout=10.0)

with httpx.Client(transport=transport) as client:
    response = client.get("https://example.com")
    print(response.status_code)
    print(response.text)

debug_transport = PyCurlTransport(
    verbose=True,
    debug_callback=lambda info_type, data: print(info_type, data),
)

Installation

pip install httpx-pycurl

Or with conda,

conda install -n base conda-pypi
conda pypi install httpx-pycurl

Performance

httpx-pycurl is in early development but it passes most httpx tests and has good performance. Our tests/bench.py uses asyncio.gather() to make many http/2 requests to https://httpbingo.org/get using httpx, niquests, and httpx with httpx-pycurl's transport. httpx-pycurl is the fastest library tested.

Running tests/bench.py [N] shows that the more efficient http/2 libraries shine when performing large numbers of parallel requests, and are closer together when only groups of 128 parallel requests are made.

2 groups of 512 requests each...

Time per group:
httpx: 0.679s ± 0.119s
niquests: 0.432s ± 0.140s
httpx_pycurl: 0.299s ± 0.056s

Paired t-test: httpx_pycurl vs niquests
t-stat: -2.249 (approx p < 0.05 if |t| > 2.365)
Speedup: 1.44x

4 groups of 256 requests each...

Time per group:
httpx: 0.378s ± 0.077s
niquests: 0.259s ± 0.064s
httpx_pycurl: 0.190s ± 0.034s

Paired t-test: httpx_pycurl vs niquests
t-stat: -4.208 (approx p < 0.05 if |t| > 2.365)
Speedup: 1.36x

8 groups of 128 requests each...

Time per group:
httpx: 0.215s ± 0.073s
niquests: 0.205s ± 0.038s
httpx_pycurl: 0.162s ± 0.033s

Paired t-test: httpx_pycurl vs niquests
t-stat: -8.949 (approx p < 0.05 if |t| > 2.365)
Speedup: 1.27x

Dependencies

httpx-pycurl uses curl to support http/2 instead of the h2, hpack and hyperframe dependencies used by httpx.

$ pip install --dry-run httpx-pycurl
...
Would install anyio-4.13.0 certifi-2026.4.22 h11-0.16.0 httpcore-1.0.9 httpx-0.28.1 httpx-pycurl-0.0.4 idna-3.13 pycurl-7.45.7

$ pip install --dry-run httpx[http2]
...
Would install anyio-4.13.0 certifi-2026.4.22 h11-0.16.0 h2-4.3.0 hpack-4.1.0 httpcore-1.0.9 httpx-0.28.1 hyperframe-6.1.0 idna-3.13