Choose a version:
23% The original file has 177847 bytes (173.7k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 40871 bytes (39.9k, 23%).

After GZIP compression these minified files vary in size:
Microsoft
  18682 bytes (18.2k)
 CDN
Boot
  17121 bytes (16.7k)
 CDN
cdnjs
  15071 bytes (14.7k)
 CDN
gzip -6 (default)
  15009 bytes (14.7k)
 local copy
gzip -9
  14990 bytes (14.6k)
 local copy
libdeflate -12
  14552 bytes (14.2k)
 local copy
7zip -mx=9 -tgzip
  14551 bytes (14.2k)
 local copy
zultra
  14527 bytes (14.2k)
 local copy
kzip -s0 -rn -b2
  14519 bytes (14.2k)
 local copy
pigz -11 -n
  14516 bytes (14.2k)
 local copy
Zopfli
  14491 bytes (14.2k)
 local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/knockout/knockout-2.2.0.min.js (or via HTTPS)

You will automatically get the smallest Knockout 2.2.0 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 580 bytes by using my Knockout 2.2.0 Zopfli version instead of the best available CDN (4.00% smaller than cdnjs, 14491 vs. 15071 bytes):
Download
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 --mls16 --bsr13 --lazy --ohh

(found December 18, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 16  --mls16
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 https://knockoutjs.com/downloads/knockout-2.2.0.js --location | md5sum
d2ca6796efcb3a731b062dbaa8c483c7  -
curl --silent --compressed https://minime.stephan-brumme.com/files/knockout/knockout-2.2.0.min.zopfli.js.gz | md5sum
d2ca6796efcb3a731b062dbaa8c483c7  -

SHA1:
curl --silent --compressed https://knockoutjs.com/downloads/knockout-2.2.0.js --location | sha1sum
0d1272c7a07350245335ce1f7c6c6b9ca59cfc0b  -
curl --silent --compressed https://minime.stephan-brumme.com/files/knockout/knockout-2.2.0.min.zopfli.js.gz | sha1sum
0d1272c7a07350245335ce1f7c6c6b9ca59cfc0b  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Microsoft 18682 bytes d2ca6796efcb3a731b062dbaa8c483c7 (invalid)
Boot 17121 bytes d2ca6796efcb3a731b062dbaa8c483c7 (invalid)
cdnjs 15071 bytes d2ca6796efcb3a731b062dbaa8c483c7 (invalid)

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

Other Versions

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

3.5.1, 3.5.0,
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
14491 bytes -1 byte zopfli --i100000 --mls16 --bsr13 --lazy --ohh December 18, 2015 @ 13:53
14492 bytes -2 bytes zopfli --i10000 --mls8 --bsr16 --lazy --ohh September 19, 2015 @ 19:26
14494 bytes -2 bytes zopfli --i10000 --mls64 --bsr9 --lazy --ohh September 18, 2015 @ 07:12
14496 bytes -1 byte zopfli --i1000 --mls256 --bsr6 --lazy --ohh September 11, 2015 @ 13:55
14497 bytes -2 bytes zopfli --i1000 --mls8192 --bsr11 --lazy --ohh September 10, 2015 @ 11:54
14499 bytes -2 bytes zopfli --i1000 --mls2048 --bsr10 --lazy --ohh September 10, 2015 @ 11:53
14501 bytes – zopfli --i100 --mls8192 --bsr8 --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 20, 2020 @ 12:51.

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
2 14496 14496 14496 14505 14505 14505 14496 14506 14506 14508 14504 14500 14512 14509 14503
4 14495 14496 14491 14494 14497 14507 14508 14505 14506 14504 14507 14506 14500 14512 14512
6 14508 14505 14494 14506 14507 14503 14505 14494 14505 14504 14506 14498 14507 14510 14507
7 14498 14499 14495 14496 14506 14496 14508 14510 14507 14507 14505 14496 14495 14507 14506
8 14496 14494 14494 14494 14508 14510 14511 14513 14506 14505 14506 14502 14498 14508 14505
9 14492 14494 14494 14511 14495 14494 14507 14507 14506 14507 14504 14500 14498 14507 14506
10 14497 14499 14507 14507 14508 14507 14508 14510 14506 14505 14498 14501 14508 14507 14500
11 14495 14495 14496 14506 14496 14502 14512 14497 14505 14505 14504 14498 14494 14507 14506
12 14494 14494 14493 14507 14508 14501 14508 14507 14506 14505 14506 14502 14507 14506 14500
13 14500 14502 14496 14491 14507 14507 14507 14497 14505 14505 14506 14496 14496 14508 14500
14 14498 14498 14507 14506 14508 14507 14507 14510 14505 14505 14505 14500 14503 14507 14506
15 14491 14499 14494 14497 14507 14501 14508 14511 14506 14505 14506 14496 14497 14507 14505
16 14500 14508 14492 14497 14506 14510 14507 14497 14506 14505 14504 14501 14498 14513 14506
17 14497 14492 14507 14494 14507 14510 14505 14496 14507 14506 14504 14498 14499 14507 14500
18 14494 14494 14494 14495 14508 14495 14505 14498 14504 14505 14506 14500 14503 14507 14500
19 14492 14495 14495 14507 14508 14507 14507 14494 14508 14505 14504 14496 14494 14511 14503
20 14497 14495 14507 14498 14507 14501 14505 14497 14505 14505 14505 14496 14497 14508 14505
21 14494 14495 14494 14494 14507 14507 14508 14510 14505 14508 14506 14500 14506 14508 14507
22 14494 14496 14494 14495 14508 14507 14508 14510 14506 14508 14506 14495 14495 14507 14503
23 14498 14497 14507 14498 14508 14507 14507 14510 14508 14507 14498 14498 14494 14508 14504
25 14491 14494 14494 14496 14508 14507 14507 14494 14508 14507 14506 14497 14494 14508 14503
30 14495 14495 14494 14495 14506 14507 14507 14495 14506 14505 14506 14502 14496 14506 14502
40 14497 14494 14495 14496 14507 14508 14508 14496 14506 14506 14505 14495 14505 14507 14504

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 14497 bytes – 100%
1,000 14495 bytes -2 bytes 100%
10,000 14492 bytes -3 bytes 100%
100,000 14491 bytes -1 byte 2.61%
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
(any) 14562 bytes +71 bytes (+0.49%) +43 bytes
1 14562 bytes +71 bytes (+0.49%) +43 bytes
2 14519 bytes +28 bytes (+0.19%) –
3 14538 bytes +47 bytes (+0.32%) +19 bytes
4 14573 bytes +82 bytes (+0.57%) +54 bytes
5 14595 bytes +104 bytes (+0.72%) +76 bytes
6 14631 bytes +140 bytes (+0.97%) +112 bytes
7 14671 bytes +180 bytes (+1.24%) +152 bytes
8 14700 bytes +209 bytes (+1.44%) +181 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 - for example, your browser actually supports it !
Algorithm Program Parameters Size Compared To Best Zopfli
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 12506 bytes -1985 bytes (-13.70%)
ZPAQ (Wikipedia) zpaq zpaq -method 69 12998 bytes -1493 bytes (-10.30%)
Brotli (Wikipedia) brotli brotli -q 11 13299 bytes -1192 bytes (-8.23%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 13366 bytes -1125 bytes (-7.76%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 13988 bytes -503 bytes (-3.47%)
LZMA2 (Wikipedia) xz xz -9 14332 bytes -159 bytes (-1.10%)
Zstandard (Wikipedia) zstd zstd -19 14503 bytes +12 bytes (+0.08%)

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):
Load and Parse Data


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 2025.
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

All trademarks are property of their respective owners. You know, the boring legal stuff.