Choose a version:
31% The original file has 279860 bytes (273.3k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 88151 bytes (86.1k, 31%).

After GZIP compression these minified files vary in size:
unpkg
  36486 bytes (35.6k)
CDN
cdnjs
  30908 bytes (30.2k)
CDN
gzip -6 (default)
  30731 bytes (30.0k)
local copy
gzip -9
  30652 bytes (29.9k)
local copy
7zip -mx=9 -tgzip
  29696 bytes (29.0k)
local copy
libdeflate -12
  29615 bytes (28.9k)
local copy
pigz -11 -n
  29595 bytes (28.9k)
local copy
kzip -s0 -rn -b2
  29590 bytes (28.9k)
local copy
Zopfli
  29571 bytes (28.9k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/jquery/jquery-3.4.0.min.js (or via HTTPS)

You will automatically get the smallest jQuery 3.4.0 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 1337 bytes by using my jQuery 3.4.0 Zopfli version instead of the best available CDN (4.52% smaller than cdnjs, 29571 vs. 30908 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 --mls256 --bsr40 --lazy --ohh

(found April 11, 2019)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 256  --mls256
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-3.4.0.min.js --location | md5sum
bbcf3bf05fa6cb58a67cfd0498f00d23  -
curl --silent --compressed https://minime.stephan-brumme.com/files/jquery/jquery-3.4.0.min.zopfli.js.gz | md5sum
bbcf3bf05fa6cb58a67cfd0498f00d23  -

SHA1:
curl --silent --compressed https://code.jquery.com/jquery-3.4.0.min.js --location | sha1sum
e4925196f6f444fa58915420fbcd80f909c68d28  -
curl --silent --compressed https://minime.stephan-brumme.com/files/jquery/jquery-3.4.0.min.zopfli.js.gz | sha1sum
e4925196f6f444fa58915420fbcd80f909c68d28  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
unpkg 36486 bytes bbcf3bf05fa6cb58a67cfd0498f00d23 (invalid)
cdnjs 30908 bytes bbcf3bf05fa6cb58a67cfd0498f00d23 April 10, 2019 @ 22:15

Note: only the MD5 hashes are shown to keep things simple.

Other Versions

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

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
29571 bytes -1 byte zopfli --i100000 --mls256 --bsr40 --lazy --ohh April 11, 2019 @ 14:02
29572 bytes -1 byte zopfli --i1000 --mls4096 --bsr40 --lazy --ohh April 11, 2019 @ 12:56
29573 bytes -1 byte zopfli --i1000 --mls256 --bsr40 --lazy --ohh April 11, 2019 @ 12:56
29574 bytes -2 bytes zopfli --i1000 --mls256 --bsr21 --lazy --ohh April 11, 2019 @ 12:55
29576 bytes zopfli --i100 --mls2048 --bsr30 --lazy --ohh April 11, 2019 @ 12:52

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

Most recent activity on April 11, 2019 @ 21:17.

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 or 1,000,000.
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
29591 29591 29574 29574 29593 29600 29591 29581 29582 29583 29584 29586 29581 29581 29600
29612 29615 29612 29574 29606 29590 29599 29577 29588 29589 29574 29581 29594 29584 29602
29588 29587 29589 29586 29592 29585 29592 29591 29587 29590 29588 29572 29593 29584 29599
29588 29586 29585 29585 29586 29591 29587 29585 29589 29587 29589 29581 29574 29579 29602
29597 29602 29606 29604 29584 29589 29578 29580 29583 29584 29587 29582 29579 29580 29601
29605 29611 29610 29604 29585 29593 29596 29579 29587 29590 29588 29581 29593 29580 29600
29587 29587 29614 29585 29585 29588 29589 29579 29586 29590 29574 29574 29590 29580 29601
29588 29585 29591 29588 29586 29585 29592 29588 29588 29587 29574 29582 29593 29580 29600
29598 29603 29594 29595 29587 29593 29586 29592 29587 29588 29588 29582 29579 29582 29601
29596 29587 29589 29586 29585 29602 29597 29583 29587 29590 29586 29574 29593 29581 29599
29586 29582 29588 29604 29588 29583 29589 29584 29589 29587 29587 29581 29574 29580 29601
29585 29587 29589 29585 29587 29589 29586 29584 29586 29587 29574 29581 29592 29579 29599
29585 29587 29584 29586 29585 29596 29588 29580 29574 29590 29574 29574 29579 29580 29599
29585 29584 29586 29601 29587 29598 29596 29590 29572 29587 29574 29574 29593 29581 29601
29584 29589 29588 29587 29585 29588 29589 29586 29589 29590 29587 29574 29593 29581 29599
29587 29587 29588 29603 29584 29589 29591 29580 29588 29588 29589 29581 29593 29583 29600
29597 29594 29593 29604 29584 29594 29586 29598 29587 29590 29572 29574 29592 29581 29599
29585 29587 29588 29604 29586 29597 29580 29572 29587 29574 29574 29582 29591 29580 29594
29587 29588 29588 29585 29584 29590 29585 29591 29587 29590 29586 29581 29589 29580 29601
29586 29583 29585 29585 29588 29586 29589 29590 29587 29587 29587 29574 29594 29580 29599
29585 29584 29588 29588 29587 29585 29589 29590 29571 29575 29574 29573 29581 29580 29599
29586 29615 29613 29586 29584 29589 29590 29579 29572 29575 29574 29574 29579 29580 29601
29586 29584 29584 29601 29585 29585 29587 29571 29589 29587 29574 29572 29579 29581 29602

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 29576 bytes 100%
1,000 29572 bytes -4 bytes 100%
10,000 29572 bytes 100%
100,000 29571 bytes -1 byte 2.61%
1,000,000 29571 bytes 0.58%
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
29669 bytes +98 bytes (+0.33%) +79 bytes
29669 bytes +98 bytes (+0.33%) +79 bytes
29590 bytes +19 bytes (+0.06%)
29600 bytes +29 bytes (+0.10%) +10 bytes
29604 bytes +33 bytes (+0.11%) +14 bytes
29644 bytes +73 bytes (+0.25%) +54 bytes
29680 bytes +109 bytes (+0.37%) +90 bytes
29722 bytes +151 bytes (+0.51%) +132 bytes
29758 bytes +187 bytes (+0.63%) +168 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 - but your browser doesn't support it.
Algorithm Program Parameters Size Compared To Best Zopfli
ZPAQ (Wikipedia) zpaq zpaq -method 69 24871 bytes -4700 bytes (-15.89%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 25219 bytes -4352 bytes (-14.72%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 26728 bytes -2843 bytes (-9.61%)
Brotli (Wikipedia) brotli brotli -q 11 27731 bytes -1840 bytes (-6.22%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 28394 bytes -1177 bytes (-3.98%)
LZMA2 (Wikipedia) xz xz -9 28944 bytes -627 bytes (-2.12%)
Zstandard (Wikipedia) zstd zstd -19 29233 bytes -338 bytes (-1.14%)

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 2019.
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