Choose a version:
21% The original file has 287743 bytes (281.0k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 60024 bytes (58.6k, 21%).

After GZIP compression these minified files vary in size:
Boot
  25440 bytes (24.8k)
CDN, direct link
cdnjs
  22393 bytes (21.9k)
CDN, direct link
gzip -6 (default)
  22223 bytes (21.7k)
local copy
cdnhttps
  22212 bytes (21.7k)
CDN, direct link
unpkg
  22212 bytes (21.7k)
CDN, direct link
gzip -9
  22187 bytes (21.7k)
local copy
jsdelivr
  22172 bytes (21.7k)
CDN, direct link
7zip -mx=9 -tgzip
  21483 bytes (21.0k)
local copy
libdeflate -12
  21472 bytes (21.0k)
local copy
kzip -s0 -rn -b4
  21470 bytes (21.0k)
local copy
pigz -11 -n
  21451 bytes (20.9k)
local copy
Zopfli
  21422 bytes (20.9k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/knockout/knockout-3.4.1.min.js

You will automatically get the smallest Knockout 3.4.1 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 750 bytes by using my Knockout 3.4.1 Zopfli version instead of the best available CDN (3.50% smaller than jsdelivr, 21422 vs. 22172 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 --i1000000 --mb8 --mls4096 --bsr21 --lazy --ohh

(found November 9, 2016)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 4096  --mls4096
block splitting recursion 21  --bsr21
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-3.4.1.js --location | md5sum
6b0bd06ac6dc55112470b993fd7bfa5f  -
curl --silent --compressed http://minime.stephan-brumme.com/files/knockout/knockout-3.4.1.min.zopfli.js.gz | md5sum
6b0bd06ac6dc55112470b993fd7bfa5f  -

SHA1:
curl --silent --compressed http://knockoutjs.com/downloads/knockout-3.4.1.js --location | sha1sum
1a635e3f98b0c84b298237b9f1e222adb721e236  -
curl --silent --compressed http://minime.stephan-brumme.com/files/knockout/knockout-3.4.1.min.zopfli.js.gz | sha1sum
1a635e3f98b0c84b298237b9f1e222adb721e236  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 25440 bytes 6b0bd06ac6dc55112470b993fd7bfa5f November 9, 2016 @ 07:04
cdnjs 22393 bytes 6b0bd06ac6dc55112470b993fd7bfa5f November 8, 2016 @ 09:02
cdnhttps 22212 bytes 6b0bd06ac6dc55112470b993fd7bfa5f November 22, 2016 @ 16:35
unpkg 22212 bytes 6b0bd06ac6dc55112470b993fd7bfa5f November 8, 2016 @ 19:41
jsdelivr 22172 bytes 6b0bd06ac6dc55112470b993fd7bfa5f November 8, 2016 @ 08:34

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

Other Versions

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

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
21422 bytes -1 byte zopfli --i1000000 --mls4096 --bsr21 --lazy --ohh November 9, 2016 @ 14:32
21423 bytes -3 bytes zopfli --i100000 --mls4096 --bsr23 --lazy --ohh November 8, 2016 @ 20:17
21426 bytes -2 bytes zopfli --i10000 --mls4096 --bsr23 --lazy --ohh November 8, 2016 @ 19:51
21428 bytes -1 byte zopfli --i1000 --mls4096 --bsr23 --lazy --ohh November 8, 2016 @ 19:49
21429 bytes zopfli --i100 --mls4096 --bsr23 --lazy --ohh November 8, 2016 @ 19:42

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

Most recent activity on January 25, 2017 @ 15:29.

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
21438 21438 21438 21440 21441 21441 21441 21439 21439 21439 21439 21432 21432 21434 21437
21439 21440 21440 21438 21443 21443 21443 21438 21444 21440 21440 21432 21432 21439 21435
21441 21443 21439 21439 21443 21442 21437 21442 21438 21440 21440 21429 21434 21432 21432
21440 21439 21441 21443 21441 21443 21438 21443 21441 21440 21438 21430 21433 21439 21437
21440 21443 21440 21441 21442 21443 21438 21438 21443 21444 21439 21426 21430 21432 21431
21437 21440 21443 21437 21442 21443 21438 21438 21438 21443 21438 21427 21435 21444 21433
21439 21439 21439 21438 21441 21443 21437 21442 21442 21440 21439 21424 21426 21443 21440
21439 21440 21443 21439 21441 21443 21438 21443 21442 21442 21439 21425 21432 21431 21431
21440 21441 21439 21444 21441 21443 21443 21440 21438 21444 21438 21424 21437 21434 21432
21441 21443 21442 21444 21442 21444 21438 21439 21438 21441 21439 21431 21435 21434 21432
21439 21439 21439 21444 21441 21444 21439 21439 21438 21442 21439 21431 21426 21433 21431
21442 21440 21441 21439 21441 21443 21443 21438 21442 21440 21438 21430 21435 21434 21439
21439 21439 21439 21439 21441 21441 21437 21443 21438 21441 21438 21429 21435 21441 21432
21440 21443 21439 21443 21441 21443 21437 21438 21442 21441 21439 21424 21426 21432 21433
21441 21439 21439 21444 21442 21441 21438 21441 21443 21444 21439 21431 21429 21435 21430
21439 21441 21443 21437 21443 21444 21439 21442 21441 21440 21439 21429 21430 21433 21433
21441 21441 21438 21439 21441 21443 21438 21439 21442 21425 21438 21429 21429 21434 21431
21439 21441 21442 21438 21442 21442 21438 21438 21443 21444 21438 21422 21430 21434 21433
21439 21439 21440 21439 21441 21443 21438 21438 21442 21444 21439 21426 21434 21442 21436
21439 21439 21439 21438 21443 21443 21437 21443 21442 21441 21437 21423 21430 21432 21433
21442 21441 21438 21438 21441 21442 21438 21440 21438 21442 21440 21427 21430 21439 21436
21439 21439 21443 21444 21442 21442 21437 21438 21442 21442 21439 21426 21429 21434 21433
21438 21440 21438 21436 21441 21439 21439 21438 21442 21442 21438 21434 21429 21433 21434

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 21429 bytes 100%
1,000 21428 bytes -1 byte 100%
10,000 21426 bytes -2 bytes 100%
100,000 21423 bytes -3 bytes 4.35%
1,000,000 21422 bytes -1 byte 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
21523 bytes +101 bytes (+0.47%) +53 bytes
21529 bytes +107 bytes (+0.50%) +59 bytes
21477 bytes +55 bytes (+0.26%) +7 bytes
21484 bytes +62 bytes (+0.29%) +14 bytes
21470 bytes +48 bytes (+0.22%)
21500 bytes +78 bytes (+0.36%) +30 bytes
21551 bytes +129 bytes (+0.60%) +81 bytes
21593 bytes +171 bytes (+0.80%) +123 bytes
21629 bytes +207 bytes (+0.97%) +159 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 18118 bytes -3304 bytes (-15.42%)
ZPAQ (Wikipedia) zpaq zpaq -method 69 18140 bytes -3282 bytes (-15.32%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 19448 bytes -1974 bytes (-9.21%)
Brotli (Wikipedia) brotli brotli -q 11 19783 bytes -1639 bytes (-7.65%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 20224 bytes -1198 bytes (-5.59%)
LZMA2 (Wikipedia) xz xz -9 20972 bytes -450 bytes (-2.10%)
ZSTD (Wikipedia) zstd zstd -19 21374 bytes -48 bytes (-0.22%)

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