Choose a version:
56% The original file has 100196 bytes (97.8k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 55774 bytes (54.5k, 56%).

After GZIP compression these minified files vary in size:
Boot
  19689 bytes (19.2k)
CDN
cdnjs
  16926 bytes (16.5k)
CDN
Baidu
  16908 bytes (16.5k)
CDN
gzip -6 (default)
  16777 bytes (16.4k)
local copy
cdnhttps
  16757 bytes (16.4k)
CDN
gzip -9
  16730 bytes (16.3k)
local copy
Google
  16729 bytes (16.3k)
CDN
libdeflate -12
  16185 bytes (15.8k)
local copy
kzip -s0 -rn -b0
  16152 bytes (15.8k)
local copy
7zip -mx=9 -tgzip
  16138 bytes (15.8k)
local copy
pigz -11 -n
  16125 bytes (15.7k)
local copy
Yandex
  16099 bytes (15.7k)
CDN
Zopfli
  16094 bytes (15.7k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/jquery/jquery-1.2.6.min.js

You will automatically get the smallest jQuery 1.2.6 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 5 bytes by using my jQuery 1.2.6 Zopfli version instead of the best available CDN (0.03% smaller than Yandex, 16094 vs. 16099 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 --bsr18 --lazy --ohh

(found January 7, 2016)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 16  --mls16
block splitting recursion 18  --bsr18
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-1.2.6.min.js --location | md5sum
a9331828c517ac5d97f93b3cfdbcc9bc  -
curl --silent --compressed http://minime.stephan-brumme.com/files/jquery/jquery-1.2.6.min.zopfli.js.gz | md5sum
a9331828c517ac5d97f93b3cfdbcc9bc  -

SHA1:
curl --silent --compressed http://code.jquery.com/jquery-1.2.6.min.js --location | sha1sum
1be9c3684054001f53fa7ff6d85ec3cb573a9cd2  -
curl --silent --compressed http://minime.stephan-brumme.com/files/jquery/jquery-1.2.6.min.zopfli.js.gz | sha1sum
1be9c3684054001f53fa7ff6d85ec3cb573a9cd2  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 19689 bytes a9331828c517ac5d97f93b3cfdbcc9bc March 18, 2015 @ 09:41
cdnjs 16926 bytes a9331828c517ac5d97f93b3cfdbcc9bc (invalid)
cdnhttps 16757 bytes a9331828c517ac5d97f93b3cfdbcc9bc December 24, 2015 @ 07:33

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
Baidu 16908 bytes 18aaf86c96cf3dedf9c01a748d92089c < * $Date: 2008-05-24 14:22:17 -0400 (Sat, 24 May 2008) $
> * $Date: 2008/05/26 $
January 7, 2015 @ 10:16
Google 16729 bytes 233898893e19f2aad95407abfc7a74fa < * $Date: 2008-05-24 14:22:17 -0400 (Sat, 24 May 2008) $
> * $Date: 2008/05/26 $
(invalid)
Yandex 16099 bytes 233898893e19f2aad95407abfc7a74fa < * $Date: 2008-05-24 14:22:17 -0400 (Sat, 24 May 2008) $
> * $Date: 2008/05/26 $
June 15, 2015 @ 21:17

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
16094 bytes -1 byte zopfli --i100000 --mls16 --bsr18 --lazy --ohh January 7, 2016 @ 14:08
16095 bytes -3 bytes zopfli --i100000 --mls4096 --bsr12 --lazy --ohh September 2, 2015 @ 01:38
16098 bytes -2 bytes zopfli --i10000 --mls4096 --bsr12 --lazy --ohh September 1, 2015 @ 21:26
16100 bytes -1 byte zopfli --i1000 --mls4096 --bsr12 --lazy --ohh September 1, 2015 @ 20:39
16101 bytes zopfli --i100 --mls8192 --bsr13 --lazy --ohh September 1, 2015 @ 20:16

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 @ 14:31.

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
16114 16100 16108 16106 16122 16101 16113 16101 16102 16101 16105 16103 16104 16102 16104
16113 16114 16116 16100 16114 16099 16113 16100 16120 16122 16102 16104 16101 16105 16106
16111 16110 16110 16101 16104 16103 16101 16104 16101 16119 16101 16101 16100 16105 16104
16116 16123 16117 16104 16113 16118 16116 16102 16117 16119 16101 16100 16100 16103 16103
16121 16122 16117 16117 16113 16114 16102 16103 16120 16116 16103 16101 16102 16103 16100
16114 16115 16119 16102 16098 16099 16103 16101 16103 16101 16101 16102 16100 16106 16103
16117 16111 16118 16100 16113 16103 16100 16099 16102 16116 16101 16102 16099 16105 16106
16098 16098 16116 16113 16106 16102 16101 16102 16103 16119 16101 16098 16102 16105 16100
16114 16115 16101 16104 16113 16102 16104 16099 16099 16100 16100 16095 16100 16103 16104
16101 16110 16116 16098 16100 16100 16103 16102 16099 16101 16100 16100 16099 16104 16104
16106 16105 16107 16102 16113 16102 16113 16118 16122 16115 16101 16100 16102 16104 16098
16101 16102 16106 16100 16101 16100 16100 16101 16101 16103 16103 16099 16099 16105 16098
16107 16099 16096 16099 16101 16101 16100 16101 16103 16116 16101 16101 16100 16099 16101
16114 16112 16099 16115 16098 16096 16100 16100 16102 16116 16101 16100 16100 16107 16102
16099 16098 16106 16094 16113 16099 16103 16102 16100 16116 16101 16101 16100 16103 16100
16113 16115 16100 16100 16113 16100 16101 16100 16117 16100 16099 16100 16100 16102 16102
16117 16115 16115 16103 16102 16100 16103 16100 16099 16102 16101 16100 16103 16103 16102
16114 16099 16116 16100 16100 16099 16103 16100 16101 16102 16100 16099 16100 16105 16101
16114 16114 16101 16101 16113 16102 16099 16100 16101 16119 16100 16100 16099 16102 16102
16113 16112 16103 16102 16113 16099 16103 16101 16100 16100 16101 16100 16099 16101 16100
16114 16115 16099 16102 16113 16098 16114 16098 16100 16101 16101 16101 16099 16101 16099
16114 16115 16100 16102 16113 16109 16098 16099 16101 16115 16101 16098 16100 16103 16101
16099 16099 16101 16104 16098 16099 16098 16100 16101 16100 16099 16100 16099 16101 16101

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 16100 bytes 100%
1,000 16098 bytes -2 bytes 100%
10,000 16097 bytes -1 byte 100%
100,000 16094 bytes -3 bytes 1.16%
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
16152 bytes +58 bytes (+0.36%)
16154 bytes +60 bytes (+0.37%) +2 bytes
16161 bytes +67 bytes (+0.42%) +9 bytes
16184 bytes +90 bytes (+0.56%) +32 bytes
16208 bytes +114 bytes (+0.71%) +56 bytes
16201 bytes +107 bytes (+0.66%) +49 bytes
16242 bytes +148 bytes (+0.92%) +90 bytes
16285 bytes +191 bytes (+1.19%) +133 bytes
16299 bytes +205 bytes (+1.27%) +147 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 13579 bytes -2515 bytes (-15.63%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 13838 bytes -2256 bytes (-14.02%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 14974 bytes -1120 bytes (-6.96%)
Brotli (Wikipedia) brotli brotli -q 11 15130 bytes -964 bytes (-5.99%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 15705 bytes -389 bytes (-2.42%)
LZMA2 (Wikipedia) xz xz -9 15872 bytes -222 bytes (-1.38%)
ZSTD (Wikipedia) zstd zstd -19 16030 bytes -64 bytes (-0.40%)

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