Choose a version:
47% The original file has 117302 bytes (114.6k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 55272 bytes (54.0k, 47%).

After GZIP compression these minified files vary in size:
Boot
  21985 bytes (21.5k)
CDN
Baidu
  19258 bytes (18.8k)
CDN
cdnjs
  19253 bytes (18.8k)
CDN
gzip -6 (default)
  19166 bytes (18.7k)
local copy
Google
  19146 bytes (18.7k)
CDN
cdnhttps
  19146 bytes (18.7k)
CDN
gzip -9
  19140 bytes (18.7k)
local copy
libdeflate -12
  18595 bytes (18.2k)
local copy
Yandex
  18523 bytes (18.1k)
CDN
7zip -mx=9 -tgzip
  18517 bytes (18.1k)
local copy
pigz -11 -n
  18504 bytes (18.1k)
local copy
kzip -s0 -rn -b3
  18490 bytes (18.1k)
local copy
Zopfli
  18474 bytes (18.0k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/jquery/jquery-1.3.1.min.js (or via HTTPS)

You will automatically get the smallest jQuery 1.3.1 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 49 bytes by using my jQuery 1.3.1 Zopfli version instead of the best available CDN (0.27% smaller than Yandex, 18474 vs. 18523 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 --bsr40 --lazy --ohh

(found November 23, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 2048  --mls2048
block splitting recursion 40  --bsr40
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 https://code.jquery.com/jquery-1.3.1.min.js --location | md5sum
5d4c7816890f3308da6126f5fa65c979  -
curl --silent --compressed https://minime.stephan-brumme.com/files/jquery/jquery-1.3.1.min.zopfli.js.gz | md5sum
5d4c7816890f3308da6126f5fa65c979  -

SHA1:
curl --silent --compressed https://code.jquery.com/jquery-1.3.1.min.js --location | sha1sum
fed603a4db640b82de54b246de4be7a1cffa8780  -
curl --silent --compressed https://minime.stephan-brumme.com/files/jquery/jquery-1.3.1.min.zopfli.js.gz | sha1sum
fed603a4db640b82de54b246de4be7a1cffa8780  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 21985 bytes 5d4c7816890f3308da6126f5fa65c979 March 18, 2015 @ 09:41
cdnjs 19253 bytes 5d4c7816890f3308da6126f5fa65c979 (invalid)
Google 19146 bytes 5d4c7816890f3308da6126f5fa65c979 (invalid)
cdnhttps 19146 bytes 5d4c7816890f3308da6126f5fa65c979 December 24, 2015 @ 07:33
Yandex 18523 bytes 5d4c7816890f3308da6126f5fa65c979 June 15, 2015 @ 21:17

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
Baidu 19258 bytes 5018fce9eaf1431e83fca0de4a735ef4 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:

3.3.1, 3.3.0,
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
18474 bytes -2 bytes zopfli --i100000 --mls2048 --bsr40 --lazy --ohh November 23, 2015 @ 13:45
18476 bytes -1 byte zopfli --i100000 --mls1024 --bsr10 --lazy --ohh October 21, 2015 @ 15:50
18477 bytes -2 bytes zopfli --i100000 --mls1024 --bsr8 --lazy --ohh September 2, 2015 @ 02:00
18479 bytes -3 bytes zopfli --i10000 --mls1024 --bsr8 --lazy --ohh September 1, 2015 @ 21:22
18482 bytes -1 byte zopfli --i1000 --mls1024 --bsr8 --lazy --ohh September 1, 2015 @ 20:40
18483 bytes zopfli --i100 --mls1024 --bsr8 --lazy --ohh September 1, 2015 @ 20:24

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 @ 14:39.

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
18506 18507 18506 18505 18505 18494 18505 18505 18503 18503 18504 18502 18493 18500 18488
18491 18489 18489 18487 18487 18487 18487 18487 18482 18484 18486 18479 18482 18483 18498
18487 18488 18488 18492 18484 18485 18506 18509 18481 18498 18479 18480 18482 18488 18492
18488 18489 18491 18485 18488 18479 18478 18474 18478 18478 18476 18478 18483 18481 18491
18483 18487 18488 18482 18488 18481 18483 18477 18483 18477 18478 18479 18482 18486 18492
18482 18486 18476 18478 18485 18486 18479 18487 18478 18491 18477 18479 18482 18494 18495
18483 18489 18490 18488 18479 18478 18478 18487 18486 18476 18477 18485 18483 18480 18493
18490 18487 18482 18487 18491 18479 18482 18488 18482 18478 18482 18484 18481 18480 18498
18489 18487 18480 18488 18487 18488 18478 18486 18490 18477 18477 18484 18482 18481 18496
18490 18488 18480 18486 18481 18485 18478 18486 18479 18478 18477 18479 18481 18496 18492
18478 18484 18484 18480 18482 18479 18479 18474 18482 18476 18479 18479 18482 18480 18493
18488 18489 18491 18489 18488 18480 18479 18476 18480 18478 18478 18479 18480 18500 18511
18490 18489 18479 18479 18482 18480 18487 18487 18482 18480 18496 18480 18482 18495 18502
18483 18491 18490 18479 18481 18481 18477 18489 18482 18479 18477 18484 18483 18483 18493
18488 18488 18486 18485 18480 18483 18481 18489 18482 18483 18476 18483 18482 18481 18503
18485 18483 18484 18487 18484 18481 18486 18477 18479 18483 18482 18480 18483 18486 18495
18486 18484 18484 18478 18483 18486 18484 18478 18487 18484 18477 18480 18483 18495 18493
18485 18486 18487 18487 18486 18487 18484 18486 18481 18479 18477 18479 18482 18480 18493
18484 18485 18485 18487 18486 18486 18485 18512 18507 18477 18480 18479 18483 18484 18498
18481 18480 18481 18477 18488 18480 18487 18487 18481 18478 18477 18479 18477 18478 18492
18491 18490 18483 18490 18483 18488 18483 18489 18479 18477 18479 18484 18482 18503 18495
18488 18477 18488 18488 18484 18478 18491 18508 18488 18478 18478 18479 18481 18483 18494
18483 18485 18481 18488 18479 18485 18476 18487 18478 18477 18474 18483 18478 18477 18498

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 18480 bytes 100%
1,000 18478 bytes -2 bytes 100%
10,000 18475 bytes -3 bytes 100%
100,000 18474 bytes -1 byte 1.74%
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
18591 bytes +117 bytes (+0.63%) +101 bytes
18591 bytes +117 bytes (+0.63%) +101 bytes
18546 bytes +72 bytes (+0.39%) +56 bytes
18490 bytes +16 bytes (+0.09%)
18523 bytes +49 bytes (+0.27%) +33 bytes
18545 bytes +71 bytes (+0.38%) +55 bytes
18568 bytes +94 bytes (+0.51%) +78 bytes
18602 bytes +128 bytes (+0.69%) +112 bytes
18622 bytes +148 bytes (+0.80%) +132 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 15389 bytes -3085 bytes (-16.70%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 15682 bytes -2792 bytes (-15.11%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 16821 bytes -1653 bytes (-8.95%)
Brotli (Wikipedia) brotli brotli -q 11 17006 bytes -1468 bytes (-7.95%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 17538 bytes -936 bytes (-5.07%)
LZMA2 (Wikipedia) xz xz -9 18032 bytes -442 bytes (-2.39%)
Zstandard (Wikipedia) zstd zstd -19 18468 bytes -6 bytes (-0.03%)

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