bencode.cy 1.2.2

A fast bencode implementation in Cython that supports Python 3. It uses Cython's pure Python syntax.

Bencode.cy

A fast bencode implementation based on Cython, supporting Python 3.9+.

The bencode functions are 15% to 230% faster than other compiled libraries, and the decode methods are 40% to 320% faster than other compiled libraries.

On average, they outperform pure Python versions by 250%.

Based on my tests, it is currently among the faster bencode libraries available.

It is written using Cython's pure Python syntax, so it can run directly without Cython compilation. Of course, performance is significantly better after compilation.

Installation

pip install bencode.cy

or, if you use uv (it might be better):

uv add bencode.cy

Usage Examples

from bencode import bencode, bdecode, compiled

assert True == compiled # Check if the code has been compiled with Cython

assert bencode("WWWWWW") == b'6:WWWWWW'
assert bencode(233) == b'i233e'

with open("debian-8.3.0-amd64-netinst.iso.torrent", "rb") as f:
    torrent = bdecode(f.read())
    print(torrent[b'announce'])

Speed Benchmark

bencode.cy.encode and bencode.cy.decode are the Cython-compiled versions of this library. bencode.cy.encodepy and bencode.cy.decodepy are the Python versions. They are the same code—one compiled, one not—which is quite interesting.

bencoder.pyx.encode and bencoder.pyx.decode are the encoding/decoding functions from the bencoder.pyx library. However, it currently only supports up to Python 3.11 and is slightly slower, though I learned a lot from its code.

fastbencode.encode and fastbencode.decode are from another excellent library, fastbencode, which is written in Rust.

better_bencode.encode and better_bencode.decode are a C version of the bencoder library from better_bencode, but I don't know why it is so slow. Maybe Python 3.11 on macOS wasn't compiled to C.

bencodepy.encode and bdecodepy.decode are part of a pure Python version of the bencoder library from BencodePy.

From the comparison, this library is currently among the fastest options. You can see more detailed results below.

deocde benchmar result

Name	OPS (Kops/s)	Mean	StdDev	Min	Max	Median	IQR	Outliers	Rounds	Iterations
bencode.cy.decode	521.4145 (1.0)	1.9179 (1.0)	0.2650 (1.0)	1.7500 (1.0)	36.3330 (1.0)	1.8750 (1.0)	0.0410 (1.0)	2174;3385	40001	1
bencode2.decode	490.4606 (0.94)	2.0389 (1.06)	1.0887 (4.11)	1.8750 (1.07)	201.3750 (5.54)	2.0000 (1.07)	0.0420 (1.02)	1082;12577	134085	1
bencode_rs.decode	485.7196 (0.93)	2.0588 (1.07)	0.5006 (1.89)	1.8750 (1.07)	64.9580 (1.79)	2.0410 (1.09)	0.0420 (1.02)	1664;16625	153847	1
bencoder.pyx.decode	191.7128 (0.37)	5.2161 (2.72)	0.6630 (2.50)	4.8750 (2.79)	95.9590 (2.64)	5.1660 (2.76)	0.0840 (2.05)	1254;5630	68185	1
bencode.cy.decodepy	164.2124 (0.31)	6.0897 (3.18)	0.6805 (2.57)	5.6670 (3.24)	97.4160 (2.68)	6.0420 (3.22)	0.1250 (3.05)	829;2364	66116	1
better_bencode.decode	134.0034 (0.26)	7.4625 (3.89)	0.8133 (3.07)	7.0000 (4.00)	84.9580 (2.34)	7.4170 (3.96)	0.0840 (2.05)	499;3408	34238	1
fastbencode.decode	123.1785 (0.24)	8.1183 (4.23)	1.1346 (4.28)	5.0000 (2.86)	107.4170 (2.96)	8.0000 (4.27)	0.2920 (7.12)	1585;3315	63493	1
bencodepy.decode	103.0055 (0.20)	9.7082 (5.06)	0.7732 (2.92)	9.1660 (5.24)	84.0830 (2.31)	9.6670 (5.16)	0.1670 (4.07)	636;1559	39089	1
bcoding.decode	53.2570 (0.10)	18.7769 (9.79)	1.7134 (6.46)	15.4580 (8.83)	90.7500 (2.50)	18.9580 (10.11)	0.5010 (12.21)	1638;1730	11205	1

encode benchmar result

Name	OPS (Kops/s)	Mean	StdDev	Min	Max	Median	IQR	Outliers	Rounds	Iterations
bencode.cy.encode	287.5983 (1.0)	3.4771 (1.0)	0.6224 (1.27)	3.2500 (1.0)	57.9590 (1.0)	3.4170 (1.0)	0.0430 (1.0)	565;8949	57143	1
bencoder.pyx.encode	256.2142 (0.89)	3.9030 (1.12)	0.4911 (1.0)	3.6660 (1.13)	93.9170 (1.62)	3.8750 (1.13)	0.0820 (1.91)	1054;3805	97163	1
bencode.cy.encodepy	188.4005 (0.66)	5.3078 (1.53)	0.5279 (1.08)	5.0000 (1.54)	72.0420 (1.24)	5.2910 (1.55)	0.0830 (1.93)	1188;8115	83620	1
bencode2.encode	183.6796 (0.64)	5.4443 (1.57)	2.0376 (4.15)	3.5840 (1.10)	68.7500 (1.19)	4.5000 (1.32)	2.7090 (62.98)	89;18	3999	1
bencode_rs.encode	145.0679 (0.50)	6.8933 (1.98)	1.5164 (3.09)	4.3330 (1.33)	60.3750 (1.04)	7.4590 (2.18)	2.5420 (59.09)	3136;32	10601	1
bcoding.encode	140.0668 (0.49)	7.1394 (2.05)	1.3146 (2.68)	6.6670 (2.05)	100.0000 (1.73)	7.0410 (2.06)	0.1660 (3.86)	410;1235	22494	1
better_bencode.encode	132.9986 (0.46)	7.5189 (2.16)	0.6240 (1.27)	7.0830 (2.18)	69.4170 (1.20)	7.4590 (2.18)	0.1260 (2.93)	754;3475	53571	1
fastbencode.encode	93.0336 (0.32)	10.7488 (3.09)	2.6568 (5.41)	8.2500 (2.54)	94.7080 (1.63)	9.2080 (2.69)	5.0420 (117.21)	7655;25	23977	1
bencodepy.encode	75.6976 (0.26)	13.2105 (3.80)	29.4086 (59.88)	8.3330 (2.56)	4,704.4170 (81.17)	9.2500 (2.71)	0.3340 (7.76)	1831;3331	51065	1

Test Environment: Python 3.11.13, MacBook Air M2, macOS 26.01, October 2025