Choose a version:
56% The original file has 96763 bytes (94.5k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 54075 bytes (52.8k, 56%).

After GZIP compression these minified files vary in size:
Boot
  18809 bytes (18.4k)
CDN, direct link
cdnjs
  16064 bytes (15.7k)
CDN, direct link
Baidu
  16043 bytes (15.7k)
CDN, direct link
gzip -6 (default)
  15925 bytes (15.6k)
local copy
cdnhttps
  15905 bytes (15.5k)
CDN, direct link
gzip -9
  15882 bytes (15.5k)
local copy
Google
  15875 bytes (15.5k)
CDN, direct link
libdeflate -12
  15347 bytes (15.0k)
local copy
kzip -s0 -rn -b1
  15336 bytes (15.0k)
local copy
7zip -mx=9 -tgzip
  15321 bytes (15.0k)
local copy
pigz -11 -n
  15290 bytes (14.9k)
local copy
Zopfli
  15276 bytes (14.9k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/jquery/jquery-1.2.3.min.js

You will automatically get the smallest jQuery 1.2.3 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 599 bytes by using my jQuery 1.2.3 Zopfli version instead of the best available CDN (3.92% smaller than Google, 15276 vs. 15875 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 --mls2048 --bsr8 --lazy --ohh

(found September 2, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 2048  --mls2048
block splitting recursion 8  --bsr8
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-1.2.3.min.js --location | md5sum
bb122b33d64d02a106bf2230b2d41af0  -
curl --silent --compressed http://minime.stephan-brumme.com/files/jquery/jquery-1.2.3.min.zopfli.js.gz | md5sum
bb122b33d64d02a106bf2230b2d41af0  -

SHA1:
curl --silent --compressed http://code.jquery.com/jquery-1.2.3.min.js --location | sha1sum
6463e558dd79d51a2e8464806824c7bbc18c77fd  -
curl --silent --compressed http://minime.stephan-brumme.com/files/jquery/jquery-1.2.3.min.zopfli.js.gz | sha1sum
6463e558dd79d51a2e8464806824c7bbc18c77fd  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 18809 bytes bb122b33d64d02a106bf2230b2d41af0 March 18, 2015 @ 09:41
cdnjs 16064 bytes bb122b33d64d02a106bf2230b2d41af0 (invalid)
cdnhttps 15905 bytes bb122b33d64d02a106bf2230b2d41af0 December 24, 2015 @ 07:33

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
Baidu 16043 bytes 8a18bb573169e8f7398b15046fd0b955 < * $Date: 2008-02-06 00:21:25 -0500 (Wed, 06 Feb 2008) $
> * $Date: 2008/05/23 $
January 7, 2015 @ 10:16
Google 15875 bytes 01a6072dcd347a552d047c48d23d2076 < * $Date: 2008-02-06 00:21:25 -0500 (Wed, 06 Feb 2008) $
> * $Date: 2008/05/23 $
(invalid)

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
15276 bytes -1 byte zopfli --i100000 --mls2048 --bsr8 --lazy --ohh September 2, 2015 @ 02:17
15277 bytes -2 bytes zopfli --i10000 --mls2048 --bsr8 --lazy --ohh September 1, 2015 @ 21:32
15279 bytes -3 bytes zopfli --i1000 --mls2048 --bsr8 --lazy --ohh September 1, 2015 @ 20:40
15282 bytes zopfli --i100 --mls2048 --bsr13 --lazy --ohh September 1, 2015 @ 20:17

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
15298 15300 15290 15290 15290 15291 15290 15292 15292 15288 15286 15288 15291 15299 15290
15295 15295 15282 15291 15284 15291 15283 15285 15283 15284 15278 15283 15282 15289 15286
15293 15303 15286 15283 15283 15285 15281 15289 15283 15282 15282 15281 15280 15296 15286
15296 15294 15295 15293 15288 15298 15295 15280 15280 15281 15282 15280 15297 15292 15285
15299 15285 15282 15281 15286 15284 15283 15285 15282 15286 15276 15279 15296 15289 15283
15294 15295 15294 15280 15279 15281 15280 15284 15283 15284 15280 15285 15281 15296 15283
15283 15293 15286 15281 15281 15282 15283 15283 15281 15281 15277 15284 15295 15291 15287
15282 15283 15281 15282 15285 15285 15282 15285 15284 15284 15282 15284 15281 15291 15279
15282 15281 15282 15285 15283 15278 15283 15282 15282 15282 15279 15282 15280 15281 15284
15293 15294 15294 15294 15284 15278 15284 15283 15282 15285 15278 15281 15296 15293 15298
15298 15285 15284 15281 15285 15285 15280 15283 15283 15285 15281 15281 15279 15283 15283
15296 15297 15294 15280 15279 15280 15285 15279 15280 15281 15276 15278 15283 15292 15285
15297 15297 15292 15282 15279 15291 15281 15280 15282 15282 15277 15282 15298 15296 15280
15294 15279 15280 15279 15282 15282 15285 15280 15282 15284 15277 15280 15290 15288 15284
15294 15293 15297 15279 15279 15280 15283 15283 15283 15283 15282 15279 15281 15296 15285
15283 15281 15280 15285 15283 15280 15282 15281 15282 15280 15277 15280 15281 15292 15285
15295 15281 15284 15281 15284 15281 15283 15282 15281 15283 15277 15282 15281 15284 15284
15282 15293 15280 15281 15279 15280 15281 15281 15282 15284 15277 15281 15281 15296 15285
15296 15293 15282 15285 15283 15284 15283 15282 15284 15283 15278 15283 15281 15296 15283
15282 15281 15283 15280 15285 15282 15284 15285 15283 15284 15278 15285 15295 15291 15280
15294 15282 15281 15285 15284 15281 15280 15282 15284 15284 15277 15280 15282 15292 15279
15289 15278 15280 15286 15279 15282 15284 15285 15280 15281 15283 15281 15277 15290 15283
15293 15293 15293 15279 15284 15283 15283 15284 15286 15280 15281 15283 15281 15296 15285

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 15279 bytes 100%
1,000 15278 bytes -1 byte 100%
10,000 15276 bytes -2 bytes 100%
100,000 15276 bytes 0.58%
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
15336 bytes +60 bytes (+0.39%)
15336 bytes +60 bytes (+0.39%)
15351 bytes +75 bytes (+0.49%) +15 bytes
15367 bytes +91 bytes (+0.60%) +31 bytes
15402 bytes +126 bytes (+0.82%) +66 bytes
15397 bytes +121 bytes (+0.79%) +61 bytes
15440 bytes +164 bytes (+1.07%) +104 bytes
15464 bytes +188 bytes (+1.23%) +128 bytes
15479 bytes +203 bytes (+1.33%) +143 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 12948 bytes -2328 bytes (-15.24%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 13141 bytes -2135 bytes (-13.98%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 14210 bytes -1066 bytes (-6.98%)
Brotli (Wikipedia) brotli brotli -q 11 14384 bytes -892 bytes (-5.84%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 14922 bytes -354 bytes (-2.32%)
LZMA2 (Wikipedia) xz xz -9 15124 bytes -152 bytes (-1.00%)
ZSTD (Wikipedia) zstd zstd -19 15251 bytes -25 bytes (-0.16%)

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 2017.
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