Choose a version:
40% The original file has 211978 bytes (207.0k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 84362 bytes (82.4k, 40%).

After GZIP compression these minified files vary in size:
Baidu
  29652 bytes (29.0k)
CDN
gzip -6 (default)
  29417 bytes (28.7k)
local copy
Google
  29399 bytes (28.7k)
CDN
gzip -9
  29353 bytes (28.7k)
local copy
kzip -s0 -rn -b0
  28348 bytes (27.7k)
local copy
7zip -mx=9 -tgzip
  28341 bytes (27.7k)
local copy
libdeflate -12
  28286 bytes (27.6k)
local copy
Yandex
  28272 bytes (27.6k)
CDN
pigz -11 -n
  28261 bytes (27.6k)
local copy
Zopfli
  28242 bytes (27.6k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/jquery/jquery-1.5.min.js (or via HTTPS)

You will automatically get the smallest jQuery 1.5 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

Save 30 bytes by using my jQuery 1.5 Zopfli version instead of the best available CDN (0.11% smaller than Yandex, 28242 vs. 28272 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 --bsr11 --lazy --ohh

(found September 2, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 2048  --mls2048
block splitting recursion 11  --bsr11
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-1.5.min.js --location | md5sum
63c1bc2eb898f68b943e1b0fdd98c746  -
curl --silent --compressed https://minime.stephan-brumme.com/files/jquery/jquery-1.5.min.zopfli.js.gz | md5sum
63c1bc2eb898f68b943e1b0fdd98c746  -

SHA1:
curl --silent --compressed https://code.jquery.com/jquery-1.5.min.js --location | sha1sum
99b7a6ecd023a00fdb104f2da21859e6bb9d49fa  -
curl --silent --compressed https://minime.stephan-brumme.com/files/jquery/jquery-1.5.min.zopfli.js.gz | sha1sum
99b7a6ecd023a00fdb104f2da21859e6bb9d49fa  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Google 29399 bytes 63c1bc2eb898f68b943e1b0fdd98c746 (invalid)
Yandex 28272 bytes 63c1bc2eb898f68b943e1b0fdd98c746 June 15, 2015 @ 21:17

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
Baidu 29652 bytes 31b653be75274e5ee8277eeac25afc1e 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
28242 bytes -3 bytes zopfli --i100000 --mls2048 --bsr11 --lazy --ohh September 2, 2015 @ 00:56
28245 bytes -1 byte zopfli --i10000 --mls2048 --bsr11 --lazy --ohh September 1, 2015 @ 21:23
28246 bytes -6 bytes zopfli --i1000 --mls2048 --bsr11 --lazy --ohh September 1, 2015 @ 20:38
28252 bytes zopfli --i100 --mls2048 --bsr11 --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 @ 14:41.

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
28262 28261 28261 28261 28262 28262 28261 28262 28261 28259 28246 28252 28250 28249 28257
28260 28257 28254 28254 28256 28258 28257 28267 28261 28261 28250 28249 28248 28248 28256
28249 28249 28248 28249 28244 28259 28251 28254 28259 28249 28250 28249 28251 28248 28247
28249 28251 28255 28253 28246 28250 28250 28253 28256 28248 28244 28249 28249 28248 28247
28249 28247 28247 28250 28247 28249 28251 28254 28257 28263 28247 28242 28248 28248 28256
28253 28250 28255 28248 28254 28257 28257 28255 28257 28250 28248 28247 28248 28247 28248
28252 28249 28250 28246 28247 28250 28249 28256 28259 28250 28249 28249 28250 28249 28248
28252 28247 28247 28250 28244 28250 28248 28257 28250 28248 28242 28249 28247 28248 28247
28247 28248 28247 28243 28245 28250 28256 28256 28250 28250 28251 28247 28250 28249 28249
28252 28251 28250 28248 28245 28250 28250 28257 28259 28253 28249 28247 28247 28248 28249
28249 28249 28251 28253 28246 28250 28256 28254 28258 28250 28248 28247 28250 28254 28248
28248 28248 28252 28252 28245 28250 28250 28255 28258 28250 28254 28249 28249 28248 28247
28253 28251 28250 28248 28245 28250 28249 28255 28258 28250 28248 28249 28250 28249 28247
28250 28249 28251 28250 28247 28249 28248 28257 28258 28250 28247 28247 28250 28249 28252
28247 28248 28247 28252 28247 28249 28256 28258 28249 28247 28247 28247 28247 28248 28248
28252 28249 28251 28254 28245 28250 28249 28260 28250 28248 28249 28249 28250 28248 28249
28251 28250 28248 28252 28247 28251 28253 28257 28258 28251 28247 28247 28250 28249 28247
28253 28248 28248 28246 28248 28248 28255 28256 28258 28248 28250 28249 28247 28249 28250
28249 28249 28248 28250 28248 28250 28250 28257 28258 28251 28245 28248 28250 28248 28247
28250 28250 28250 28250 28253 28255 28250 28257 28249 28247 28250 28249 28248 28248 28249
28250 28252 28247 28252 28247 28250 28248 28256 28259 28261 28250 28247 28250 28249 28247
28250 28251 28251 28248 28247 28250 28248 28256 28257 28263 28248 28246 28249 28248 28247
28250 28252 28247 28251 28245 28249 28248 28256 28258 28262 28247 28247 28249 28248 28249

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 28252 bytes 100%
1,000 28246 bytes -6 bytes 100%
10,000 28244 bytes -2 bytes 100%
100,000 28242 bytes -2 bytes 3.77%
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
28348 bytes +106 bytes (+0.38%)
28349 bytes +107 bytes (+0.38%) +1 byte
28390 bytes +148 bytes (+0.52%) +42 bytes
28374 bytes +132 bytes (+0.47%) +26 bytes
28384 bytes +142 bytes (+0.50%) +36 bytes
28418 bytes +176 bytes (+0.62%) +70 bytes
28431 bytes +189 bytes (+0.67%) +83 bytes
28454 bytes +212 bytes (+0.75%) +106 bytes
28492 bytes +250 bytes (+0.89%) +144 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 22814 bytes -5428 bytes (-19.22%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 23486 bytes -4756 bytes (-16.84%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 24681 bytes -3561 bytes (-12.61%)
Brotli (Wikipedia) brotli brotli -q 11 26089 bytes -2153 bytes (-7.62%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 26271 bytes -1971 bytes (-6.98%)
LZMA2 (Wikipedia) xz xz -9 27176 bytes -1066 bytes (-3.77%)
Zstandard (Wikipedia) zstd zstd -19 27795 bytes -447 bytes (-1.58%)

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