Choose a version:
44% The original file has 158407 bytes (154.7k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 69838 bytes (68.2k, 44%).

After GZIP compression these minified files vary in size:
Boot
  27428 bytes (26.8k)
CDN
Baidu
  23958 bytes (23.4k)
CDN
cdnjs
  23882 bytes (23.3k)
CDN
gzip -6 (default)
  23740 bytes (23.2k)
local copy
Google
  23722 bytes (23.2k)
CDN
cdnhttps
  23722 bytes (23.2k)
CDN
gzip -9
  23697 bytes (23.1k)
local copy
7zip -mx=9 -tgzip
  23002 bytes (22.5k)
local copy
kzip -s0 -rn -b3
  22972 bytes (22.4k)
local copy
libdeflate -12
  22972 bytes (22.4k)
local copy
Yandex
  22934 bytes (22.4k)
CDN
pigz -11 -n
  22928 bytes (22.4k)
local copy
Zopfli
  22880 bytes (22.3k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/jquery/jquery-1.4.min.js

You will automatically get the smallest jQuery 1.4 file, ETag caching is available and
if your browser doesn't support GZIP decompression then the uncompressed version will be sent.

Currently best Zopfli settings

Save 54 bytes by using my jQuery 1.4 Zopfli version instead of the best available CDN (0.24% smaller than Yandex, 22880 vs. 22934 bytes):
You can use my super-compressed files for whatever purpose you like as long as you respect the library's original license agreement.
There are no restrictions from my side - but please avoid hot-linking if you run a high-traffic website.

These command-line settings yielded the best compression ratio so far (Linux version of zopfli-krzymod):
zopfli --i100000 --mb8 --mls16 --bsr10 --lazy --ohh

(found January 7, 2016)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 16  --mls16
block splitting recursion 10  --bsr10
lazy matching in LZ77 yes  --lazy
optimized Huffman headers yes  --ohh
initial random W for iterations 1  --rw1
initial random Z for iterations 2  --rz2

Verify file integrity

After decompression, my uncompressed files are identical to the original ones:

MD5:
curl --silent --compressed http://code.jquery.com/jquery-1.4.min.js --location | md5sum
7df0a08f438c12a75b267cc83bfa03e8  -
curl --silent --compressed http://minime.stephan-brumme.com/files/jquery/jquery-1.4.min.zopfli.js.gz | md5sum
7df0a08f438c12a75b267cc83bfa03e8  -

SHA1:
curl --silent --compressed http://code.jquery.com/jquery-1.4.min.js --location | sha1sum
b5efe44645f5358e3d785091af3440f80afa85e3  -
curl --silent --compressed http://minime.stephan-brumme.com/files/jquery/jquery-1.4.min.zopfli.js.gz | sha1sum
b5efe44645f5358e3d785091af3440f80afa85e3  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 27428 bytes 7df0a08f438c12a75b267cc83bfa03e8 March 18, 2015 @ 09:41
cdnjs 23882 bytes 7df0a08f438c12a75b267cc83bfa03e8 (invalid)
Google 23722 bytes 7df0a08f438c12a75b267cc83bfa03e8 (invalid)
cdnhttps 23722 bytes 7df0a08f438c12a75b267cc83bfa03e8 December 24, 2015 @ 07:33
Yandex 22934 bytes 7df0a08f438c12a75b267cc83bfa03e8 June 15, 2015 @ 21:17

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
Baidu 23958 bytes 9e936b27d8d0e4e07ebef242d7c6e2cc only whitespaces differ January 7, 2015 @ 10:16

Note: only the MD5 hashes are shown to keep things simple.

Other Versions

Available jQuery versions at minime.stephan-brumme.com:

3.2.1, 3.2.0,
3.1.1, 3.1.0,
3.0.0,
2.2.4, 2.2.3, 2.2.2, 2.2.1, 2.2.0,
2.1.4, 2.1.3, 2.1.2, 2.1.1, 2.1.0,
2.0.3, 2.0.2, 2.0.1, 2.0.0,
1.12.4, 1.12.3, 1.12.2, 1.12.1, 1.12.0,
1.11.3, 1.11.2, 1.11.1, 1.11.0,
1.10.2, 1.10.1, 1.10.0,
1.9.1, 1.9.0,
1.8.3, 1.8.2, 1.8.1, 1.8.0,
1.7.2, 1.7.1, 1.7.0,
1.6.4, 1.6.3, 1.6.2, 1.6.1, 1.6,
1.5.2, 1.5.1, 1.5,
1.4.4, 1.4.3, 1.4.2, 1.4.1, 1.4,
1.3.2, 1.3.1, 1.3,
1.2.6, 1.2.5, 1.2.4, 1.2.3, 1.2.2, 1.2.1, 1.2,
1.1.4, 1.1.3, 1.1.2, 1.1.1, 1.1,
1.0.4, 1.0.3, 1.0.2, 1.0.1, 1.0

The project site contains an overview how well these versions were compressed.
Other interesting projects are AngularJS, BackboneJS, Bootstrap, D3, Dojo, Ember, Knockout, lodash, React, Socket.IO, ThreeJS, UnderscoreJS and Vue.

Changelog

Best Zopfli parameters so far:
Size Improvement Parameters Found
22880 bytes -2 bytes zopfli --i100000 --mls16 --bsr10 --lazy --ohh January 7, 2016 @ 16:30
22882 bytes -1 byte zopfli --i100000 --mls32 --bsr11 --lazy --ohh November 23, 2015 @ 13:50
22883 bytes -1 byte zopfli --i100000 --mls32 --bsr40 --lazy --ohh October 21, 2015 @ 16:10
22884 bytes -2 bytes zopfli --i100000 --mls512 --bsr9 --lazy --ohh September 2, 2015 @ 02:50
22886 bytes -2 bytes zopfli --i10000 --mls512 --bsr9 --lazy --ohh September 1, 2015 @ 21:19
22888 bytes -3 bytes zopfli --i1000 --mls512 --bsr9 --lazy --ohh September 1, 2015 @ 20:39
22891 bytes zopfli --i100 --mls512 --bsr11 --lazy --ohh September 1, 2015 @ 20:15

If there are multiple parameter sets yielding the same compressed size, only the first one found is shown.

Most recent activity on June 16, 2016 @ 14:40.

Heatmaps

This Zopfli heatmap visualizes how compression changes when modifying the --bsr and --mls parameter.
Cell's contents is the best filesize achieved (in bytes, hover with mouse over cells to see number of iterations).

Good parameters are green, bad are red. The best and worst are bold as well.
The brightness of the blue background color indicates how many iterations were processed:
10,000 or 100,000.
bsr \ mls
2 4 8 16 32 64 128 256 512 1024 2048 4096 8192 16384 32768
bsr \ mls
2 4 8 16 32 64 128 256 512 1024 2048 4096 8192 16384 32768
22920 22921 22921 22927 22927 22927 22927 22931 22926 22925 22925 22930 22934 22934 22936
22921 22921 22922 22920 22921 22921 22921 22885 22921 22922 22920 22923 22927 22933 22892
22890 22890 22929 22899 22898 22883 22924 22884 22887 22920 22927 22929 22929 22931 22927
22886 22887 22920 22921 22921 22887 22921 22887 22925 22925 22921 22923 22930 22932 22934
22890 22891 22894 22921 22885 22924 22923 22888 22887 22920 22921 22922 22931 22926 22932
22890 22890 22889 22886 22885 22885 22924 22888 22884 22921 22921 22929 22927 22929 22892
22887 22890 22888 22880 22919 22890 22921 22887 22886 22920 22920 22928 22928 22931 22892
22890 22890 22921 22919 22882 22887 22920 22884 22887 22920 22920 22919 22927 22930 22892
22891 22890 22890 22885 22921 22922 22884 22884 22922 22920 22920 22921 22927 22930 22928
22890 22889 22889 22888 22891 22887 22884 22889 22887 22921 22920 22923 22927 22931 22927
22895 22888 22887 22886 22884 22890 22921 22888 22887 22920 22921 22924 22926 22927 22933
22889 22889 22890 22885 22921 22885 22884 22884 22886 22920 22921 22923 22927 22927 22934
22886 22886 22886 22890 22885 22928 22884 22884 22888 22920 22921 22928 22928 22928 22928
22890 22889 22885 22885 22884 22889 22924 22887 22885 22920 22920 22921 22930 22929 22933
22889 22889 22896 22889 22886 22885 22926 22884 22886 22920 22921 22926 22927 22932 22925
22887 22887 22886 22884 22921 22885 22923 22883 22886 22921 22921 22919 22925 22927 22900
22889 22889 22884 22892 22885 22885 22921 22884 22887 22920 22921 22926 22928 22931 22933
22889 22891 22888 22884 22885 22889 22884 22888 22887 22920 22921 22921 22928 22928 22892
22887 22887 22887 22886 22885 22928 22922 22887 22886 22921 22920 22926 22927 22931 22933
22890 22891 22884 22884 22923 22887 22885 22885 22922 22920 22921 22918 22928 22929 22894
22890 22924 22886 22885 22884 22896 22921 22884 22923 22920 22921 22929 22926 22928 22933
22887 22887 22891 22889 22884 22887 22923 22885 22887 22920 22921 22921 22928 22932 22927
22887 22886 22886 22884 22883 22884 22921 22887 22887 22921 22921 22926 22927 22929 22934

Due to the Monte Carlo design of my search algorithm, not all parameters have reached the same number of iterations yet:
Iterations Min. Bytes Reduction Coverage
100 22888 bytes 100%
1,000 22885 bytes -3 bytes 100%
10,000 22883 bytes -2 bytes 100%
100,000 22880 bytes -3 bytes 2.03%
1,000,000
10,000,000

KZIP has far less options available for tuning/optimization. I only played around with the number of blocks (parameter -n):
Blocks Min. Bytes Compared To Best Zopfli Compared To Best KZIP
22981 bytes +101 bytes (+0.44%) +9 bytes
22981 bytes +101 bytes (+0.44%) +9 bytes
23005 bytes +125 bytes (+0.55%) +33 bytes
22972 bytes +92 bytes (+0.40%)
22978 bytes +98 bytes (+0.43%) +6 bytes
23021 bytes +141 bytes (+0.62%) +49 bytes
23020 bytes +140 bytes (+0.61%) +48 bytes
23051 bytes +171 bytes (+0.75%) +79 bytes
23068 bytes +188 bytes (+0.82%) +96 bytes

Non-DEFLATE Algorithms

Archivers based on completely different compression algorithms often produce superior results.
Unfortunately, browsers only support gzip compression at the moment.
Algorithm Program Parameters Size Compared To Best Zopfli
ZPAQ (Wikipedia) zpaq zpaq -method 69 19132 bytes -3748 bytes (-16.38%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 19464 bytes -3416 bytes (-14.93%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 20141 bytes -2739 bytes (-11.97%)
Brotli (Wikipedia) brotli brotli -q 11 21225 bytes -1655 bytes (-7.23%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 21939 bytes -941 bytes (-4.11%)
LZMA2 (Wikipedia) xz xz -9 22324 bytes -556 bytes (-2.43%)
ZSTD (Wikipedia) zstd zstd -19 22673 bytes -207 bytes (-0.90%)

Detailled Analysis

I wrote a DEFLATE decoder in Javascript. Click the button below to start a client-side analysis of the smallest gzipped files (may take a second):


Notes: pigz is a fast open source multi-threaded implementation of gzip written by one of the original authors of gzip.
However, when using compression level 11, pigz actually switches to the slower Zopfli algorithm and isn't multi-threaded anymore.
KrzyMOD's extensions to Zopfli offer the highest level of configuration and is therefore used for my brute-force search.
Ken Silverman wrote the closed-source KZIP compression program and Jonathon Fowler ported it to Linux.
Defluff was created by Joachim Henke; DeflOpt is a tool by Ben Jos Walbeehm.

website made by Stephan Brumme in 2015 and still improving in 2018.
all timestamps are displayed in central european time. see my changelog.
no flash, not even images or external css files - and everything squeezed into a single html file.
which was handsomely compressed before releasing it into the wild internet - obviously.

please visit my homepage and my blog, too.
email: minime (at) stephan-brumme.com