Choose a version:
21% The original file has 260844 bytes (254.7k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 54129 bytes (52.9k, 21%).

After GZIP compression these minified files vary in size:
Microsoft
  24898 bytes (24.3k)
CDN
Boot
  22902 bytes (22.4k)
CDN
cdnjs
  20130 bytes (19.7k)
CDN
gzip -6 (default)
  19980 bytes (19.5k)
local copy
cdnhttps
  19958 bytes (19.5k)
CDN
gzip -9
  19942 bytes (19.5k)
local copy
unpkg
  19933 bytes (19.5k)
CDN
jsdelivr
  19929 bytes (19.5k)
CDN
libdeflate -12
  19336 bytes (18.9k)
local copy
7zip -mx=9 -tgzip
  19335 bytes (18.9k)
local copy
kzip -s0 -rn -b2
  19315 bytes (18.9k)
local copy
pigz -11 -n
  19301 bytes (18.8k)
local copy
Zopfli
  19273 bytes (18.8k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/knockout/knockout-3.2.0.min.js (or via HTTPS)

You will automatically get the smallest Knockout 3.2.0 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 656 bytes by using my Knockout 3.2.0 Zopfli version instead of the best available CDN (3.40% smaller than jsdelivr, 19273 vs. 19929 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 --i10000 --mb8 --mls4096 --bsr6 --lazy --ohh

(found September 10, 2015)
Description Value Parameter
iterations 10000  --i10000
maximum blocks 8  --mb8
maximum length score 4096  --mls4096
block splitting recursion 6  --bsr6
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-3.2.0.js --location | md5sum
f8219fcd0b579bd438b91a0f7648eba8  -
curl --silent --compressed https://minime.stephan-brumme.com/files/knockout/knockout-3.2.0.min.zopfli.js.gz | md5sum
f8219fcd0b579bd438b91a0f7648eba8  -

SHA1:
curl --silent --compressed http://knockoutjs.com/downloads/knockout-3.2.0.js --location | sha1sum
c4d160b17b587fbeacecdd9006499f5c817b0dde  -
curl --silent --compressed https://minime.stephan-brumme.com/files/knockout/knockout-3.2.0.min.zopfli.js.gz | sha1sum
c4d160b17b587fbeacecdd9006499f5c817b0dde  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Microsoft 24898 bytes f8219fcd0b579bd438b91a0f7648eba8 (invalid)
Boot 22902 bytes f8219fcd0b579bd438b91a0f7648eba8 (invalid)
cdnjs 20130 bytes f8219fcd0b579bd438b91a0f7648eba8 (invalid)
cdnhttps 19958 bytes f8219fcd0b579bd438b91a0f7648eba8 December 24, 2015 @ 07:33
jsdelivr 19929 bytes f8219fcd0b579bd438b91a0f7648eba8 (invalid)

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
unpkg 19933 bytes 7c32f9e123c8b648776f6c469e403eb6 < (function() {(function(p){var s=this||(0,eval)("this"),v=s [...]
< c=setTimeout(a,d)}}function I(b,d,c,e){a.d[b]={init:functi [...]
< a.b("version",a.version);a.a=function(){function b(a,b){fo [...]
< 0,d=b.length;c<d;c++)h[b[c]]=a});var k={propertychange:!0} [...]
< b)return c;return-1},qb:function(a,b,c){for(var d=0,f=a.le [...]
< Array)a.push.apply(a,b);else for(var c=0,d=b.length;c<d;c+ [...]
< 0,f=b.length,e=[];d<f;d++){var k=b[d].cloneNode(!0);e.push [...]
< 0;c!==d;)if(a.push(c),c=c.nextSibling,!c)return;a.push(d)} [...]
< 16);for(;a&&a!=b;)a=a.parentNode;return!!a},Ja:function(b) [...]
< else b.addEventListener(c,d,!1)},oa:function(b,c){if(!b||! [...]
[...]
July 11, 2016 @ 16:43

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
19273 bytes -2 bytes zopfli --i10000 --mls4096 --bsr6 --lazy --ohh September 10, 2015 @ 12:36
19275 bytes -1 byte zopfli --i10000 --mls1024 --bsr12 --lazy --ohh September 10, 2015 @ 12:28
19276 bytes -1 byte zopfli --i1000 --mls4096 --bsr10 --lazy --ohh September 10, 2015 @ 11:45
19277 bytes -3 bytes zopfli --i1000 --mls1024 --bsr12 --lazy --ohh September 10, 2015 @ 11:44
19280 bytes zopfli --i100 --mls1024 --bsr10 --lazy --ohh September 10, 2015 @ 11:35

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
19291 19292 19291 19291 19290 19291 19291 19289 19289 19289 19290 19279 19294 19294 19296
19291 19293 19292 19293 19289 19290 19288 19288 19289 19288 19290 19294 19286 19291 19291
19289 19293 19290 19290 19290 19289 19288 19290 19288 19288 19289 19273 19290 19290 19292
19292 19293 19291 19292 19289 19290 19289 19289 19289 19288 19290 19293 19294 19292 19291
19289 19293 19290 19289 19289 19289 19288 19288 19289 19289 19290 19279 19288 19294 19290
19289 19291 19291 19290 19289 19290 19288 19290 19288 19288 19289 19286 19293 19294 19289
19292 19292 19291 19292 19289 19290 19289 19290 19289 19274 19288 19274 19286 19290 19289
19293 19292 19291 19293 19289 19289 19290 19288 19289 19288 19288 19286 19290 19290 19288
19292 19292 19291 19289 19290 19289 19289 19288 19289 19274 19290 19274 19290 19292 19293
19289 19292 19291 19291 19290 19290 19288 19288 19288 19274 19290 19283 19289 19290 19291
19292 19293 19292 19289 19289 19290 19288 19288 19288 19288 19288 19293 19290 19295 19290
19292 19292 19292 19292 19290 19290 19288 19288 19288 19274 19290 19274 19289 19290 19290
19290 19293 19290 19289 19289 19290 19288 19287 19288 19275 19288 19283 19290 19290 19288
19289 19292 19291 19289 19289 19290 19288 19288 19289 19289 19288 19273 19288 19290 19290
19290 19293 19291 19290 19288 19288 19289 19289 19288 19274 19289 19283 19286 19290 19290
19289 19292 19290 19290 19290 19289 19287 19288 19288 19288 19289 19274 19278 19290 19290
19292 19293 19292 19289 19289 19290 19289 19289 19289 19289 19289 19286 19285 19290 19292
19289 19293 19290 19291 19289 19289 19288 19290 19288 19274 19289 19274 19289 19290 19289
19289 19293 19292 19290 19289 19289 19289 19288 19289 19288 19289 19286 19288 19291 19288
19290 19292 19290 19290 19289 19289 19289 19290 19287 19289 19289 19283 19289 19292 19288
19289 19292 19290 19289 19289 19289 19289 19288 19287 19289 19288 19282 19288 19290 19289
19292 19292 19290 19291 19289 19290 19289 19289 19288 19277 19289 19275 19279 19290 19290
19290 19293 19291 19291 19290 19290 19288 19288 19289 19288 19290 19286 19289 19294 19289

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 19280 bytes 100%
1,000 19275 bytes -5 bytes 100%
10,000 19273 bytes -2 bytes 100%
100,000 19273 bytes 4.35%
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
19362 bytes +89 bytes (+0.46%) +47 bytes
19362 bytes +89 bytes (+0.46%) +47 bytes
19315 bytes +42 bytes (+0.22%)
19329 bytes +56 bytes (+0.29%) +14 bytes
19374 bytes +101 bytes (+0.52%) +59 bytes
19417 bytes +144 bytes (+0.75%) +102 bytes
19419 bytes +146 bytes (+0.76%) +104 bytes
19461 bytes +188 bytes (+0.98%) +146 bytes
19498 bytes +225 bytes (+1.17%) +183 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
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 16372 bytes -2901 bytes (-15.05%)
ZPAQ (Wikipedia) zpaq zpaq -method 69 16616 bytes -2657 bytes (-13.79%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 17570 bytes -1703 bytes (-8.84%)
Brotli (Wikipedia) brotli brotli -q 11 17695 bytes -1578 bytes (-8.19%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 18279 bytes -994 bytes (-5.16%)
LZMA2 (Wikipedia) xz xz -9 18888 bytes -385 bytes (-2.00%)
Zstandard (Wikipedia) zstd zstd -19 19240 bytes -33 bytes (-0.17%)

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