Choose a version:
33% The original file has 258549 bytes (252.5k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 85630 bytes (83.6k, 33%).

After GZIP compression these minified files vary in size:
Microsoft
  38407 bytes (37.5k)
CDN
Boot
  34929 bytes (34.1k)
CDN
cdnhttps
  33660 bytes (32.9k)
CDN
cdnjs
  30127 bytes (29.4k)
CDN
gzip -6 (default)
  29947 bytes (29.2k)
local copy
unpkg
  29936 bytes (29.2k)
CDN
gzip -9
  29902 bytes (29.2k)
local copy
Google
  29895 bytes (29.2k)
CDN
jsdelivr
  29892 bytes (29.2k)
CDN
7zip -mx=9 -tgzip
  28942 bytes (28.3k)
local copy
libdeflate -12
  28890 bytes (28.2k)
local copy
Yandex
  28877 bytes (28.2k)
CDN
pigz -11 -n
  28868 bytes (28.2k)
local copy
kzip -s0 -rn -b2
  28856 bytes (28.2k)
local copy
Zopfli
  28829 bytes (28.2k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/jquery/jquery-2.2.1.min.js

You will automatically get the smallest jQuery 2.2.1 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 48 bytes by using my jQuery 2.2.1 Zopfli version instead of the best available CDN (0.17% smaller than Yandex, 28829 vs. 28877 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 --i10000000 --mb8 --mls32 --bsr4 --lazy --ohh

(found February 27, 2016)
Description Value Parameter
iterations 10000000  --i10000000
maximum blocks 8  --mb8
maximum length score 32  --mls32
block splitting recursion 4  --bsr4
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-2.2.1.min.js --location | md5sum
6cbb321051a268424103cd4aea8ffa66  -
curl --silent --compressed http://minime.stephan-brumme.com/files/jquery/jquery-2.2.1.min.zopfli.js.gz | md5sum
6cbb321051a268424103cd4aea8ffa66  -

SHA1:
curl --silent --compressed http://code.jquery.com/jquery-2.2.1.min.js --location | sha1sum
7cb05e3d551cd61439337b2cb22f49b1955f9711  -
curl --silent --compressed http://minime.stephan-brumme.com/files/jquery/jquery-2.2.1.min.zopfli.js.gz | sha1sum
7cb05e3d551cd61439337b2cb22f49b1955f9711  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Microsoft 38407 bytes 6cbb321051a268424103cd4aea8ffa66 February 26, 2016 @ 19:07
Boot 34929 bytes 6cbb321051a268424103cd4aea8ffa66 February 23, 2016 @ 15:02
cdnhttps 33660 bytes 6cbb321051a268424103cd4aea8ffa66 November 24, 2016 @ 16:42
cdnjs 30127 bytes 6cbb321051a268424103cd4aea8ffa66 February 23, 2016 @ 06:47
unpkg 29936 bytes 6cbb321051a268424103cd4aea8ffa66 July 11, 2016 @ 15:38
Google 29895 bytes 6cbb321051a268424103cd4aea8ffa66 March 18, 2016 @ 22:26
jsdelivr 29892 bytes 6cbb321051a268424103cd4aea8ffa66 February 22, 2016 @ 21:02
Yandex 28877 bytes 6cbb321051a268424103cd4aea8ffa66 (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
28829 bytes -1 byte zopfli --i10000000 --mls32 --bsr4 --lazy --ohh February 27, 2016 @ 15:38
28830 bytes -1 byte zopfli --i1000000 --mls32 --bsr4 --lazy --ohh February 24, 2016 @ 16:17
28831 bytes -1 byte zopfli --i100000 --mls32 --bsr4 --lazy --ohh February 24, 2016 @ 11:01
28832 bytes -1 byte zopfli --i1000000 --mls64 --bsr20 --lazy --ohh February 23, 2016 @ 19:54
28833 bytes -3 bytes zopfli --i100000 --mls64 --bsr20 --lazy --ohh February 23, 2016 @ 13:46
28836 bytes -1 byte zopfli --i10000 --mls64 --bsr20 --lazy --ohh February 23, 2016 @ 12:04
28837 bytes -1 byte zopfli --i10000 --mls32 --bsr2 --lazy --ohh February 23, 2016 @ 12:00
28838 bytes -2 bytes zopfli --i1000 --mls32 --bsr2 --lazy --ohh February 23, 2016 @ 11:16
28840 bytes -1 byte zopfli --i1000 --mls64 --bsr2 --lazy --ohh February 23, 2016 @ 11:15
28841 bytes -1 byte zopfli --i1000 --mls16 --bsr12 --lazy --ohh February 23, 2016 @ 11:15
28842 bytes zopfli --i100 --mls16 --bsr12 --lazy --ohh February 23, 2016 @ 10:49

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

Most recent activity on November 24, 2016 @ 16:42.

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, 100,000, 1,000,000 or 10,000,000.
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
28843 28844 28849 28844 28834 28837 28852 28851 28846 28847 28849 28849 28845 28844 28869
28842 28842 28850 28852 28829 28863 28850 28851 28856 28852 28845 28845 28846 28844 28843
28851 28846 28850 28853 28854 28852 28852 28850 28850 28851 28843 28846 28845 28848 28844
28851 28849 28850 28839 28840 28852 28849 28851 28850 28852 28840 28843 28844 28846 28854
28851 28852 28839 28838 28846 28862 28850 28854 28852 28853 28842 28845 28846 28847 28848
28852 28850 28842 28839 28840 28863 28850 28850 28852 28853 28840 28846 28845 28848 28849
28852 28853 28839 28839 28851 28863 28851 28850 28852 28851 28841 28846 28849 28844 28844
28840 28849 28860 28842 28838 28851 28849 28850 28851 28850 28842 28844 28845 28848 28847
28852 28850 28840 28840 28851 28867 28851 28852 28850 28853 28840 28844 28845 28848 28849
28851 28852 28845 28841 28850 28863 28850 28851 28850 28853 28842 28846 28845 28848 28848
28838 28852 28853 28840 28837 28836 28842 28841 28852 28851 28840 28843 28845 28848 28843
28852 28852 28844 28854 28858 28852 28849 28850 28853 28850 28840 28843 28843 28846 28848
28840 28849 28839 28840 28851 28864 28850 28850 28850 28851 28839 28843 28846 28847 28847
28838 28839 28839 28844 28836 28838 28850 28850 28850 28851 28845 28844 28845 28846 28848
28851 28849 28840 28855 28842 28841 28850 28837 28850 28852 28842 28846 28845 28848 28849
28851 28849 28845 28839 28848 28864 28850 28850 28851 28851 28840 28845 28845 28844 28843
28840 28839 28840 28839 28843 28832 28850 28851 28850 28850 28843 28845 28846 28847 28848
28841 28850 28839 28840 28844 28843 28850 28839 28850 28851 28841 28845 28845 28846 28847
28852 28849 28852 28840 28852 28839 28850 28839 28852 28850 28843 28843 28845 28847 28843
28852 28850 28853 28853 28843 28865 28850 28850 28852 28853 28840 28844 28845 28847 28847
28839 28841 28840 28840 28852 28843 28850 28850 28851 28851 28843 28844 28845 28846 28842
28840 28852 28839 28843 28844 28865 28849 28850 28851 28850 28840 28844 28845 28848 28846
28841 28839 28839 28850 28842 28863 28850 28852 28850 28851 28842 28843 28845 28848 28847

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 28842 bytes 100%
1,000 28838 bytes -4 bytes 100%
10,000 28834 bytes -4 bytes 100%
100,000 28831 bytes -3 bytes 0.87%
1,000,000 28830 bytes -1 byte 0.58%
10,000,000 28829 bytes -1 byte 0.29%

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
28956 bytes +127 bytes (+0.44%) +100 bytes
28956 bytes +127 bytes (+0.44%) +100 bytes
28856 bytes +27 bytes (+0.09%)
28864 bytes +35 bytes (+0.12%) +8 bytes
28873 bytes +44 bytes (+0.15%) +17 bytes
28920 bytes +91 bytes (+0.32%) +64 bytes
28941 bytes +112 bytes (+0.39%) +85 bytes
28992 bytes +163 bytes (+0.57%) +136 bytes
29029 bytes +200 bytes (+0.69%) +173 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 23960 bytes -4869 bytes (-16.89%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 24461 bytes -4368 bytes (-15.15%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 25919 bytes -2910 bytes (-10.09%)
Brotli (Wikipedia) brotli brotli -q 11 26989 bytes -1840 bytes (-6.38%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 27308 bytes -1521 bytes (-5.28%)
LZMA2 (Wikipedia) xz xz -9 28096 bytes -733 bytes (-2.54%)
ZSTD (Wikipedia) zstd zstd -19 28619 bytes -210 bytes (-0.73%)

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