curl_cffi

Documentation

Python binding for curl-impersonate fork via cffi. For commercial support, visit impersonate.pro.

curl_cffi is the most popular Python binding for curl. Unlike other pure python http clients like httpx or requests, curl_cffi can impersonate browsers' TLS/JA3 and HTTP/2 fingerprints. If you are blocked by some website for no obvious reason, you can give curl_cffi a try.

For JavaScript bindings, see impers, for solving JavaScript challenges, see brimp.

Python 3.10 is the minimum supported version since v0.14.

Recent highlights

• 🧭 Our new toy, brimp, a lightweight browser, works like curl_cffi with JavaScript enabled. Try it out today!
• 🆕 Added support for the new algorithm and extensions in Chrome 150/152.

Recall.ai - API for meeting recordings

If you’re looking for a meeting recording API, consider checking out Recall.ai, an API that records Zoom, Google Meet, Microsoft Teams, in-person meetings, and more.

Sponsors

Maintenance of this project is made possible by all the contributors and sponsors. If you'd like to sponsor this project and have your avatar or company logo appear below click here. 💖

Bypass Cloudflare with API

Yescaptcha is a proxy service that bypasses Cloudflare and uses the API interface to obtain verified cookies (e.g. cf_clearance). Click here to register: https://yescaptcha.com/i/stfnIO

TLS fingerprinting alone isn't enough for modern bot protection. Hyper Solutions provides the missing piece - API endpoints that generate valid antibot tokens for:

Akamai • DataDome • Kasada • Incapsula

No browser automation. Just simple API calls that return the exact cookies and headers these systems require.

🚀 Get Your API Key | 📖 Docs | 💬 Discord

cloro: SERP and AI search API for Google, ChatGPT, Perplexity, Gemini, Copilot and Grok

Impersonate Suite

curl-cffi is part of the impersonate suite.

• curl-impersonate. A curl distribution that impersonates browsers.
• curl_cffi. Python binding to curl-impersonate.
• brimp. Browser-impersonate, a lightweight browser
• impers. Node.js binding to curl-impersonate.
• impersonate.pro. Commercial support, more fingerprints and cloud offering.

Features

• Supports JA3/TLS and http2 fingerprints impersonation, including recent browsers and custom fingerprints.
• Much faster than requests/httpx, on par with aiohttp/pycurl, see benchmarks.
• Mimics the requests API, no need to learn another one.
• Pre-compiled, so you don't have to compile on your machine.
• Supports asyncio with proxy rotation on each request.
• Supports http 2.0, which requests does not.
• Supports http 3.0, with fingerprints and udp proxy.
• Supports websocket.
• MIT licensed.

Notes:

1. For pycurl, http/3 is usually disabled at compile time by default.
2. http/3 support since v0.11.4, http/3 proxy and fingerprints since v0.15.0.

Install

pip install curl_cffi --upgrade

This should work on Linux, macOS and Windows out of the box.

On macOS, you can also install via Homebrew:

brew install lexiforest/tap/curl-cffi

To install beta releases:

pip install curl_cffi --upgrade --pre

To install unstable version from GitHub:

git clone https://github.com/lexiforest/curl_cffi/
cd curl_cffi
make preprocess
pip install .

Usage

curl_cffi comes with a low-level curl API and a high-level requests-like API. curl_cffi also bundles with a CLI called curl-cffi.

CLI

Since v0.15, curl_cffi comes with a CLI called curl-cffi, you can use it for debugging a certain url with the --impersonate option. It can also serve as a web_fetch replacement for "agents".

curl-cffi get tls.browserleaks.com/json

# curl-cffi can be hard to type, use an alias if you want
alias imp=curl-cffi
imp get tls.browserleaks.com/json --impersonate chrome

For a complete CLI guide, see docs.

requests-like

import curl_cffi

# Notice the impersonate parameter
r = curl_cffi.get("https://tls.browserleaks.com/json", impersonate="chrome")

print(r.json())
# output: {..., "ja3n_hash": "aa56c057ad164ec4fdcb7a5a283be9fc", ...}
# the js3n fingerprint should be the same as target browser

# To keep using the latest browser version as `curl_cffi` updates,
# simply set impersonate="chrome" without specifying a version.
# Other similar values are: "safari" and "safari_ios"
r = curl_cffi.get("https://tls.browserleaks.com/json", impersonate="chrome")

# Use http/3 with impersonation
r = curl_cffi.get(
    "https://fp.impersonate.pro/api/http3",
    http_version="v3",
    impersonate="chrome"
)

# To pin a specific version, use version numbers together.
r = curl_cffi.get("https://tls.browserleaks.com/json", impersonate="chrome124")

# To impersonate other than browsers, bring your own ja3/akamai strings
# See examples directory for details.
r = curl_cffi.get("https://tls.browserleaks.com/json", ja3=..., akamai=...)

# http/socks proxies are supported
proxies = {"https": "http://localhost:3128"}
r = curl_cffi.get("https://tls.browserleaks.com/json", impersonate="chrome", proxies=proxies)

proxies = {"https": "socks://localhost:3128"}
r = curl_cffi.get("https://tls.browserleaks.com/json", impersonate="chrome", proxies=proxies)

Sessions

s = curl_cffi.Session()

# httpbin is a http test website, this endpoint makes the server set cookies
s.get("https://httpbin.org/cookies/set/foo/bar")
print(s.cookies)
# <Cookies[<Cookie foo=bar for httpbin.org />]>

# retrieve cookies again to verify
r = s.get("https://httpbin.org/cookies")
print(r.json())
# {'cookies': {'foo': 'bar'}}

Supported impersonate browsers

curl_cffi supports the same browser versions preset as supported by our fork of curl-impersonate:

The open source version of curl_cffi includes versions when we are adding new capabilities for impersonating. If you see a version, e.g. chrome135, was skipped, it's simply because there's nothing new or we were busy at that time. You can simply impersonate it with your own headers and the previous browser target.

For a full list of preset fingerprints, see the curl-impersonate docs. We will no longer put duplicated and outdated info here.

If you don't want to look up the headers/etc by yourself, consider buying commercial support from impersonate.pro. We have comprehensive browser tls, http and JavaScript fingerprints database for almost all the browser versions on various platforms.

Since v0.15.1, you can use curl-cffi update to retrieve the latest fingerprints, without updating to a new version. We offer the Safari, Chrome, Firefox updates for free and others as part of the commercial plan.

The current number of fingerprints:

To see the current list of fingerprints on your device, use the command line:

curl-cffi list

To update fingerprints from impersonate.pro, use the command line:

curl-cffi update

If you are trying to impersonate a target other than a browser, use ja3=..., akamai=..., extra_fp=..., and perk=... to specify your own customized fingerprints. See the docs on impersonation for details.

Asyncio

from curl_cffi import AsyncSession

async with AsyncSession() as s:
    r = await s.get("https://example.com")

More concurrency:

import asyncio
from curl_cffi import AsyncSession

urls = [
    "https://google.com/",
    "https://facebook.com/",
    "https://twitter.com/",
]

async with AsyncSession() as s:
    tasks = []
    for url in urls:
        task = s.get(url)
        tasks.append(task)
    results = await asyncio.gather(*tasks)

For low-level APIs, Scrapy integration and other advanced topics, see the docs for more details.

WebSockets

curl_cffi provides an advanced Python interface to libcurl's WebSocket client. Handshake requests automatically inherit all session settings — such as browser impersonation (TLS/JA3 and HTTP/2), custom proxies, and headers, enabling seamless connections to servers protected by strict anti-bot systems.

WebSockets can be used synchronously, through standard blocking methods, direct iteration, or by using an event-driven callback model (similar to websocket-client):

from curl_cffi import Session, WebSocket

with Session() as session:
    # Handshake automatically inherits browser fingerprints (Chrome, Safari, etc.)
    with session.ws_connect("wss://echo.websocket.org", impersonate="chrome") as ws:
        ws.send_str("Hello, World!", timeout=5.0)

        # Standard block-and-read
        msg = ws.recv_str(timeout=5.0)
        print(f"Received: {msg}")

        for i in range(10):
            ws.send_str(f"Stream #{i}")

        # Stream incoming messages sequentially
        for message, _ in zip(ws, range(11)):
            print(message)

def on_message(ws, message):
    print(f"Received: {message}")

# Automatically negotiates upgrades and listens continuously
ws = WebSocket(on_message=on_message)
ws.run_forever("wss://api.gemini.com/v1/marketdata/BTCUSD")

For high-performance applications, the async client supports concurrent receiving and sending (similar to aiohttp):

import asyncio
from curl_cffi import AsyncSession

async def main():
    async with AsyncSession() as session:
        async with session.ws_connect("wss://echo.websocket.org", impersonate="chrome") as ws:
            # Execute concurrent sends
            await asyncio.gather(*[ws.send_str(f"Message {i}") for i in range(10)])

            # Receive messages
            received = await asyncio.gather(*[ws.recv_str() for i in range(11)])
            for frame in received:
                print(frame)

async def stream():
    async with AsyncSession() as session:
        async with session.ws_connect("wss://api.gemini.com/v1/marketdata/BTCUSD") as ws:
            # Stream incoming frames asynchronously
            async for message in ws:
                print(f"Asyncio Stream: {message}")

asyncio.run(main())  # or stream()

Features

• Impersonation & Session Inheritance: Inherits browser fingerprints (TLS/JA3 and HTTP/2), custom proxies, and headers directly during the initial handshake request.
• SIMD Performance: Frame payload masking is executed using SIMD hardware acceleration (AVX-512, AVX2, and ARM NEON) inside a customized libcurl build.
• Automatic Message Reassembly: Automatically assembles fragmented WebSocket frames in the background, so messages are always delivered complete.
• Robust Network Resiliency: Built with precise timeout boundaries and transient error recovery to safely handle network conditions without corrupting connection state.

See the WebSocket docs for full details and advanced options.

Ecosystem

• Integrating with Scrapy: divtiply/scrapy-curl-cffi, jxlil/scrapy-impersonate and tieyongjie/scrapy-fingerprint.
• Integrating with requests, httpx as adapter.
• Integrating with captcha resolvers: YesCaptcha.

Acknowledgement

• Originally forked from multippt/python_curl_cffi, which is under the MIT license.
• Headers/Cookies files are copied from httpx, which is under the BSD license.
• Asyncio support is inspired by Tornado's curl http client.
• The synchronous WebSocket API is inspired by websocket_client.
• The asynchronous WebSocket API is inspired by aiohttp.

Contributing

When submitting an PR, please use a different branch other than main and check the "Allow edits by maintainers" box, so I can update your PR with lint or style fixes. Thanks!

AI Policy

• Using AI is neither encouraged nor discouraged, use it by your own choice.
• The bottom line here is that every line of code should be reviewed by human, and should be proven to work.
• It's not guaranteed that AI will come up with the cleanest solution, you are responsible to guide it to the right way you know.
• Fix any lint errors, make sure your code follows the established convention in this project.
• LLM tends to generate extensive or none comments, revise the comments and make sure they are concise and helpful.
• It's absolutely not acceptable to generate the entire PR summary by LLM. To communicate with other human, use words from a human.
• The only acceptable exception is to fix grammar issues if you are not a native English speaker.
• The essence here is to keep Human in the loop

You can even feed the policy above to your "copilot" to let it adjust the style for you. :P