Choose a version:
23% The original file has 183211 bytes (178.9k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 42732 bytes (41.7k, 23%).

After GZIP compression these minified files vary in size:
Boot
  17832 bytes (17.4k)
CDN
cdnjs
  15699 bytes (15.3k)
CDN
gzip -6 (default)
  15602 bytes (15.2k)
local copy
unpkg
  15591 bytes (15.2k)
CDN
gzip -9
  15587 bytes (15.2k)
local copy
cdnhttps
  15580 bytes (15.2k)
CDN
jsdelivr
  15565 bytes (15.2k)
CDN
7zip -mx=9 -tgzip
  15145 bytes (14.8k)
local copy
libdeflate -12
  15131 bytes (14.8k)
local copy
kzip -s0 -rn -b2
  15116 bytes (14.8k)
local copy
pigz -11 -n
  15096 bytes (14.7k)
local copy
Zopfli
  15083 bytes (14.7k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/knockout/knockout-2.3.0.min.js

You will automatically get the smallest Knockout 2.3.0 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 482 bytes by using my Knockout 2.3.0 Zopfli version instead of the best available CDN (3.20% smaller than jsdelivr, 15083 vs. 15565 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 --bsr13 --lazy --ohh

(found November 13, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 2048  --mls2048
block splitting recursion 13  --bsr13
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-2.3.0.js --location | md5sum
48d1c61386189c99e1bf5192089226b7  -
curl --silent --compressed http://minime.stephan-brumme.com/files/knockout/knockout-2.3.0.min.zopfli.js.gz | md5sum
48d1c61386189c99e1bf5192089226b7  -

SHA1:
curl --silent --compressed http://knockoutjs.com/downloads/knockout-2.3.0.js --location | sha1sum
5a1c94104bd542372746ea8843829a28cdd3dee2  -
curl --silent --compressed http://minime.stephan-brumme.com/files/knockout/knockout-2.3.0.min.zopfli.js.gz | sha1sum
5a1c94104bd542372746ea8843829a28cdd3dee2  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 17832 bytes 48d1c61386189c99e1bf5192089226b7 (invalid)
cdnjs 15699 bytes 48d1c61386189c99e1bf5192089226b7 (invalid)
unpkg 15591 bytes 48d1c61386189c99e1bf5192089226b7 July 11, 2016 @ 16:43
cdnhttps 15580 bytes 48d1c61386189c99e1bf5192089226b7 December 24, 2015 @ 07:33
jsdelivr 15565 bytes 48d1c61386189c99e1bf5192089226b7 (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
15083 bytes -1 byte zopfli --i100000 --mls2048 --bsr13 --lazy --ohh November 13, 2015 @ 18:17
15084 bytes -1 byte zopfli --i100000 --mls32768 --bsr8 --lazy --ohh November 13, 2015 @ 18:17
15085 bytes -2 bytes zopfli --i10000 --mls2048 --bsr13 --lazy --ohh September 10, 2015 @ 13:27
15087 bytes -1 byte zopfli --i1000 --mls2048 --bsr13 --lazy --ohh September 10, 2015 @ 11:50
15088 bytes zopfli --i100 --mls2048 --bsr13 --lazy --ohh September 10, 2015 @ 11:37

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
15092 15094 15094 15094 15095 15094 15095 15095 15096 15090 15089 15096 15097 15094 15098
15090 15090 15090 15091 15090 15092 15090 15094 15092 15090 15091 15092 15090 15090 15089
15091 15099 15091 15091 15092 15091 15090 15091 15092 15099 15091 15088 15092 15091 15089
15094 15098 15093 15090 15091 15097 15102 15089 15091 15093 15089 15090 15090 15090 15098
15089 15089 15090 15099 15091 15098 15090 15091 15092 15093 15091 15090 15090 15090 15084
15088 15093 15093 15100 15098 15096 15089 15091 15090 15091 15091 15094 15090 15090 15091
15089 15089 15091 15091 15099 15099 15095 15091 15090 15090 15091 15099 15090 15090 15089
15093 15098 15092 15098 15098 15098 15098 15095 15091 15090 15091 15090 15090 15090 15090
15099 15091 15099 15099 15099 15091 15090 15092 15091 15092 15091 15088 15090 15089 15089
15091 15090 15099 15091 15091 15097 15095 15091 15092 15093 15083 15091 15090 15091 15090
15089 15089 15098 15099 15091 15092 15090 15090 15094 15093 15091 15090 15091 15091 15089
15094 15097 15099 15100 15099 15097 15098 15089 15092 15092 15089 15089 15090 15090 15090
15089 15090 15098 15090 15092 15099 15090 15091 15092 15091 15091 15091 15090 15090 15091
15090 15092 15099 15100 15098 15098 15096 15090 15090 15093 15092 15089 15090 15090 15091
15089 15091 15099 15091 15101 15089 15090 15092 15092 15091 15091 15090 15090 15090 15089
15094 15091 15093 15100 15091 15091 15089 15091 15092 15093 15091 15090 15090 15090 15090
15089 15092 15091 15100 15099 15099 15090 15091 15092 15091 15091 15090 15092 15090 15090
15094 15098 15099 15091 15091 15091 15090 15091 15093 15093 15091 15090 15090 15091 15091
15089 15090 15092 15100 15091 15099 15095 15091 15093 15090 15091 15088 15090 15089 15091
15094 15093 15093 15100 15099 15098 15098 15089 15091 15091 15091 15088 15090 15090 15095
15094 15098 15099 15100 15099 15096 15095 15091 15093 15092 15091 15091 15090 15090 15091
15091 15089 15091 15091 15098 15098 15090 15090 15092 15091 15091 15091 15090 15090 15089
15099 15090 15099 15100 15099 15096 15095 15090 15093 15092 15091 15086 15090 15090 15089

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 15087 bytes 100%
1,000 15086 bytes -1 byte 100%
10,000 15085 bytes -1 byte 100%
100,000 15083 bytes -2 bytes 0.87%
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
15153 bytes +70 bytes (+0.46%) +37 bytes
15153 bytes +70 bytes (+0.46%) +37 bytes
15116 bytes +33 bytes (+0.22%)
15154 bytes +71 bytes (+0.47%) +38 bytes
15190 bytes +107 bytes (+0.71%) +74 bytes
15228 bytes +145 bytes (+0.96%) +112 bytes
15270 bytes +187 bytes (+1.24%) +154 bytes
15317 bytes +234 bytes (+1.55%) +201 bytes
15323 bytes +240 bytes (+1.59%) +207 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 12944 bytes -2139 bytes (-14.18%)
ZPAQ (Wikipedia) zpaq zpaq -method 69 13351 bytes -1732 bytes (-11.48%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 13871 bytes -1212 bytes (-8.04%)
Brotli (Wikipedia) brotli brotli -q 11 13872 bytes -1211 bytes (-8.03%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 14486 bytes -597 bytes (-3.96%)
LZMA2 (Wikipedia) xz xz -9 14936 bytes -147 bytes (-0.97%)
ZSTD (Wikipedia) zstd zstd -19 15144 bytes +61 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):


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