Choose a version:
22% The original file has 210761 bytes (205.8k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 46129 bytes (45.0k, 22%).

After GZIP compression these minified files vary in size:
Microsoft
  21207 bytes (20.7k)
CDN, direct link
Boot
  19442 bytes (19.0k)
CDN, direct link
cdnjs
  17104 bytes (16.7k)
CDN, direct link
gzip -6 (default)
  16998 bytes (16.6k)
local copy
unpkg
  16980 bytes (16.6k)
CDN, direct link
cdnhttps
  16976 bytes (16.6k)
CDN, direct link
gzip -9
  16961 bytes (16.6k)
local copy
jsdelivr
  16945 bytes (16.5k)
CDN, direct link
7zip -mx=9 -tgzip
  16498 bytes (16.1k)
local copy
libdeflate -12
  16474 bytes (16.1k)
local copy
kzip -s0 -rn -b2
  16469 bytes (16.1k)
local copy
pigz -11 -n
  16461 bytes (16.1k)
local copy
Zopfli
  16448 bytes (16.1k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/knockout/knockout-3.0.0.min.js

You will automatically get the smallest Knockout 3.0.0 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 497 bytes by using my Knockout 3.0.0 Zopfli version instead of the best available CDN (3.02% smaller than jsdelivr, 16448 vs. 16945 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 --bsr4 --lazy --ohh

(found December 18, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 256  --mls256
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://knockoutjs.com/downloads/knockout-3.0.0.js --location | md5sum
104d5d1d77adfc68cf2b08fb37c237a7  -
curl --silent --compressed http://minime.stephan-brumme.com/files/knockout/knockout-3.0.0.min.zopfli.js.gz | md5sum
104d5d1d77adfc68cf2b08fb37c237a7  -

SHA1:
curl --silent --compressed http://knockoutjs.com/downloads/knockout-3.0.0.js --location | sha1sum
753a6fac5d94e316e995d118c78b7d21b3bbaab6  -
curl --silent --compressed http://minime.stephan-brumme.com/files/knockout/knockout-3.0.0.min.zopfli.js.gz | sha1sum
753a6fac5d94e316e995d118c78b7d21b3bbaab6  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Microsoft 21207 bytes 104d5d1d77adfc68cf2b08fb37c237a7 (invalid)
Boot 19442 bytes 104d5d1d77adfc68cf2b08fb37c237a7 (invalid)
cdnjs 17104 bytes 104d5d1d77adfc68cf2b08fb37c237a7 (invalid)
unpkg 16980 bytes 104d5d1d77adfc68cf2b08fb37c237a7 July 11, 2016 @ 16:43
cdnhttps 16976 bytes 104d5d1d77adfc68cf2b08fb37c237a7 December 24, 2015 @ 07:33
jsdelivr 16945 bytes 104d5d1d77adfc68cf2b08fb37c237a7 (invalid)

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

Other Versions

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

3.4.2, 3.4.1, 3.4.0,
3.3.0,
3.2.0,
3.1.0,
3.0.0,
2.3.0,
2.2.1, 2.2.0,
2.1.0,
2.0.0,
1.2.1, 1.2.0,
1.1.2, 1.1.1, 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, jQuery, lodash, React, Socket.IO, ThreeJS, UnderscoreJS and Vue.

Changelog

Best Zopfli parameters so far:
Size Improvement Parameters Found
16448 bytes -2 bytes zopfli --i100000 --mls256 --bsr4 --lazy --ohh December 18, 2015 @ 09:37
16450 bytes -2 bytes zopfli --i100000 --mls2048 --bsr13 --lazy --ohh December 18, 2015 @ 07:36
16452 bytes -1 byte zopfli --i1000 --mls512 --bsr9 --lazy --ohh September 10, 2015 @ 11:48
16453 bytes -2 bytes zopfli --i1000 --mls512 --bsr11 --lazy --ohh September 10, 2015 @ 11:48
16455 bytes zopfli --i100 --mls512 --bsr11 --lazy --ohh September 10, 2015 @ 11:34

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

Most recent activity on July 11, 2016 @ 16:43.

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
16461 16465 16464 16462 16457 16455 16461 16460 16455 16455 16457 16456 16459 16460 16460
16461 16451 16451 16450 16450 16450 16449 16448 16451 16454 16455 16460 16453 16459 16458
16460 16461 16459 16460 16460 16461 16471 16460 16459 16459 16450 16455 16453 16457 16455
16460 16460 16460 16464 16450 16450 16454 16455 16450 16451 16449 16452 16456 16455 16456
16457 16456 16460 16458 16458 16458 16459 16458 16459 16454 16455 16452 16456 16457 16458
16460 16460 16460 16458 16450 16450 16461 16450 16450 16451 16455 16457 16457 16462 16458
16459 16459 16459 16458 16460 16457 16461 16458 16459 16450 16449 16452 16457 16464 16457
16459 16460 16460 16458 16457 16450 16460 16449 16450 16454 16450 16450 16452 16465 16457
16458 16460 16459 16461 16457 16450 16454 16450 16450 16450 16459 16459 16452 16466 16475
16458 16460 16459 16460 16458 16461 16458 16455 16455 16451 16450 16458 16455 16459 16458
16460 16460 16456 16459 16458 16450 16455 16450 16451 16454 16449 16456 16456 16466 16456
16459 16459 16460 16461 16460 16450 16460 16455 16450 16451 16455 16457 16456 16459 16457
16460 16458 16459 16458 16457 16450 16454 16455 16459 16459 16455 16459 16454 16465 16457
16461 16460 16460 16457 16451 16450 16471 16454 16450 16451 16461 16452 16452 16459 16458
16460 16460 16459 16459 16458 16449 16458 16454 16455 16450 16450 16452 16455 16465 16455
16461 16460 16459 16460 16450 16450 16454 16450 16451 16454 16459 16456 16455 16467 16456
16461 16460 16460 16460 16459 16449 16455 16460 16451 16454 16455 16455 16456 16459 16457
16459 16460 16460 16459 16458 16460 16454 16454 16459 16451 16450 16452 16452 16457 16456
16460 16460 16459 16461 16458 16450 16454 16454 16459 16451 16457 16456 16454 16465 16458
16461 16460 16460 16461 16459 16460 16454 16449 16458 16451 16454 16455 16456 16465 16458
16460 16460 16460 16461 16457 16450 16454 16457 16451 16450 16449 16452 16453 16456 16456
16459 16460 16460 16457 16457 16450 16459 16449 16450 16451 16459 16452 16453 16465 16458
16460 16460 16459 16460 16457 16460 16459 16460 16459 16454 16450 16455 16454 16455 16456

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 16454 bytes 100%
1,000 16452 bytes -2 bytes 100%
10,000 16452 bytes 100%
100,000 16448 bytes -4 bytes 24.35%
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
16519 bytes +71 bytes (+0.43%) +50 bytes
16518 bytes +70 bytes (+0.43%) +49 bytes
16469 bytes +21 bytes (+0.13%)
16475 bytes +27 bytes (+0.16%) +6 bytes
16503 bytes +55 bytes (+0.33%) +34 bytes
16542 bytes +94 bytes (+0.57%) +73 bytes
16575 bytes +127 bytes (+0.77%) +106 bytes
16605 bytes +157 bytes (+0.95%) +136 bytes
16648 bytes +200 bytes (+1.22%) +179 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
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 14055 bytes -2393 bytes (-14.55%)
ZPAQ (Wikipedia) zpaq zpaq -method 69 14440 bytes -2008 bytes (-12.21%)
Brotli (Wikipedia) brotli brotli -q 11 15145 bytes -1303 bytes (-7.92%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 15256 bytes -1192 bytes (-7.25%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 15688 bytes -760 bytes (-4.62%)
LZMA2 (Wikipedia) xz xz -9 16216 bytes -232 bytes (-1.41%)
ZSTD (Wikipedia) zstd zstd -19 16490 bytes +42 bytes (+0.26%)

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 2017.
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