Choose a version:
56% The original file has 99997 bytes (97.7k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 55715 bytes (54.4k, 56%).

After GZIP compression these minified files vary in size:
gzip -6 (default)
  16753 bytes (16.4k)
 local copy
gzip -9
  16710 bytes (16.3k)
 local copy
libdeflate -12
  16132 bytes (15.8k)
 local copy
kzip -s0 -rn -b0
  16128 bytes (15.8k)
 local copy
7zip -mx=9 -tgzip
  16111 bytes (15.7k)
 local copy
zultra
  16104 bytes (15.7k)
 local copy
pigz -11 -n
  16087 bytes (15.7k)
 local copy
Zopfli
  16071 bytes (15.7k)
 local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/jquery/jquery-1.2.5.min.js (or via HTTPS)

You will automatically get the smallest jQuery 1.2.5 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

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 --mls32 --bsr18 --lazy --ohh

(found January 7, 2016)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 32  --mls32
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 https://code.jquery.com/jquery-1.2.5.min.js --location | md5sum
85b7cbe520e2449c84b04769bce1b45a  -
curl --silent --compressed https://minime.stephan-brumme.com/files/jquery/jquery-1.2.5.min.zopfli.js.gz | md5sum
85b7cbe520e2449c84b04769bce1b45a  -

SHA1:
curl --silent --compressed https://code.jquery.com/jquery-1.2.5.min.js --location | sha1sum
20860bad9c83c3890be57052f009b9d97848c9ec  -
curl --silent --compressed https://minime.stephan-brumme.com/files/jquery/jquery-1.2.5.min.zopfli.js.gz | sha1sum
20860bad9c83c3890be57052f009b9d97848c9ec  -

Other Versions

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

3.6.1, 3.6.0,
3.5.1, 3.5.0,
3.4.1, 3.4.0,
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
16071 bytes -1 byte zopfli --i100000 --mls32 --bsr18 --lazy --ohh January 7, 2016 @ 13:01
16072 bytes -2 bytes zopfli --i100000 --mls32 --bsr7 --lazy --ohh October 21, 2015 @ 15:49
16074 bytes -1 byte zopfli --i10000 --mls32 --bsr7 --lazy --ohh October 21, 2015 @ 15:24
16075 bytes -1 byte zopfli --i100000 --mls4096 --bsr13 --lazy --ohh September 2, 2015 @ 03:08
16076 bytes -1 byte zopfli --i10000 --mls4096 --bsr13 --lazy --ohh September 1, 2015 @ 21:33
16077 bytes -2 bytes zopfli --i1000 --mls4096 --bsr13 --lazy --ohh September 1, 2015 @ 20:39
16079 bytes – zopfli --i100 --mls8192 --bsr11 --lazy --ohh September 1, 2015 @ 20:22

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

Most recent activity on July 20, 2020 @ 13:08.

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
2 16080 16079 16091 16086 16092 16085 16077 16085 16082 16088 16081 16082 16080 16078 16090
4 16097 16098 16099 16078 16083 16094 16096 16096 16097 16077 16077 16083 16077 16082 16081
6 16086 16096 16099 16075 16075 16080 16081 16081 16080 16097 16080 16079 16078 16080 16082
7 16078 16097 16101 16078 16072 16078 16097 16078 16095 16076 16083 16078 16078 16077 16077
8 16081 16082 16083 16077 16071 16080 16095 16078 16089 16094 16081 16079 16079 16081 16078
9 16099 16092 16101 16079 16080 16095 16097 16098 16080 16080 16079 16079 16079 16079 16080
10 16098 16095 16095 16082 16075 16094 16094 16094 16080 16095 16077 16077 16078 16080 16079
11 16097 16091 16078 16084 16092 16094 16095 16080 16081 16095 16085 16079 16076 16078 16078
12 16076 16075 16080 16080 16076 16079 16079 16078 16080 16076 16078 16078 16080 16082 16081
13 16097 16094 16096 16079 16076 16079 16078 16078 16093 16079 16079 16075 16078 16075 16077
14 16096 16093 16096 16079 16079 16078 16096 16098 16096 16080 16078 16078 16075 16081 16080
15 16076 16076 16077 16080 16076 16079 16076 16076 16078 16075 16084 16077 16078 16080 16074
16 16075 16075 16081 16078 16076 16079 16079 16079 16081 16076 16077 16074 16080 16082 16079
17 16087 16095 16081 16081 16076 16094 16095 16078 16078 16080 16080 16076 16077 16077 16080
18 16077 16076 16079 16078 16071 16078 16081 16080 16081 16094 16077 16077 16076 16077 16077
19 16098 16099 16078 16080 16076 16094 16097 16099 16082 16080 16084 16076 16077 16079 16078
20 16087 16095 16077 16077 16076 16080 16079 16077 16079 16076 16080 16079 16075 16080 16081
21 16080 16080 16081 16080 16075 16079 16079 16095 16081 16094 16082 16083 16079 16082 16079
22 16088 16079 16079 16081 16074 16078 16094 16095 16077 16096 16079 16079 16078 16079 16080
23 16098 16095 16081 16079 16075 16076 16095 16093 16094 16077 16082 16079 16078 16079 16080
25 16075 16075 16081 16079 16076 16080 16079 16080 16079 16079 16078 16078 16078 16080 16077
30 16097 16095 16097 16095 16071 16095 16095 16079 16082 16080 16079 16078 16077 16079 16076
40 16099 16077 16082 16080 16077 16076 16078 16077 16079 16094 16080 16083 16077 16082 16078

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 16079 bytes – 100%
1,000 16075 bytes -4 bytes 100%
10,000 16073 bytes -2 bytes 100%
100,000 16071 bytes -2 bytes 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
(any) 16128 bytes +57 bytes (+0.35%) –
1 16129 bytes +58 bytes (+0.36%) +1 byte
2 16138 bytes +67 bytes (+0.42%) +10 bytes
3 16160 bytes +89 bytes (+0.55%) +32 bytes
4 16182 bytes +111 bytes (+0.69%) +54 bytes
5 16178 bytes +107 bytes (+0.67%) +50 bytes
6 16217 bytes +146 bytes (+0.91%) +89 bytes
7 16262 bytes +191 bytes (+1.19%) +134 bytes
8 16277 bytes +206 bytes (+1.28%) +149 bytes

Non-DEFLATE Algorithms

Archivers based on completely different compression algorithms often produce superior results.
Unfortunately, browsers only support gzip compression at the moment.
However, support for Brotli is constantly growing - for example, your browser actually supports it !
Algorithm Program Parameters Size Compared To Best Zopfli
ZPAQ (Wikipedia) zpaq zpaq -method 69 13559 bytes -2512 bytes (-15.63%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 13819 bytes -2252 bytes (-14.01%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 14959 bytes -1112 bytes (-6.92%)
Brotli (Wikipedia) brotli brotli -q 11 15108 bytes -963 bytes (-5.99%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 15674 bytes -397 bytes (-2.47%)
LZMA2 (Wikipedia) xz xz -9 15848 bytes -223 bytes (-1.39%)
Zstandard (Wikipedia) zstd zstd -19 16007 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):
Load and Parse Data


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 2024.
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

All trademarks are property of their respective owners. You know, the boring legal stuff.