Choose a version:
26% The original file has 623859 bytes (609.2k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 161911 bytes (158.1k, 26%).

After GZIP compression these minified files vary in size:
gzip -6 (default)
  54732 bytes (53.4k)
local copy
gzip -9
  54681 bytes (53.4k)
local copy
libdeflate -12
  52035 bytes (50.8k)
local copy
7zip -mx=9 -tgzip
  52023 bytes (50.8k)
local copy
pigz -11 -n
  51997 bytes (50.8k)
local copy
kzip -s0 -rn -b1
  51977 bytes (50.8k)
local copy
Zopfli
  51887 bytes (50.7k)
local copy
Zopfli (defluff)
  51886 bytes (50.7k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/dojo/dojo-1.9.9.min.js

You will automatically get the smallest Dojo 1.9.9 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

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 --mls8 --bsr15 --lazy --ohh

(found June 13, 2016)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 8  --mls8
block splitting recursion 15  --bsr15
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

Even Smaller Files Thanks To Defluff

Zopfli's output can be further optimized by the defluff tool.
In this particular case, defluff saves 1 more byte (51886 bytes).

Verify file integrity

After decompression, my uncompressed files are identical to the original ones:

MD5:
curl --silent --compressed http://download.dojotoolkit.org/release-1.9.9/dojo.js --location | md5sum
6b0fbe059516f3df29ff4db463cc9528  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.9.9.min.zopfli.js.gz | md5sum
6b0fbe059516f3df29ff4db463cc9528  -

SHA1:
curl --silent --compressed http://download.dojotoolkit.org/release-1.9.9/dojo.js --location | sha1sum
4a1b4c1b397c2fc0fba4c89c961944959538fc5b  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.9.9.min.zopfli.js.gz | sha1sum
4a1b4c1b397c2fc0fba4c89c961944959538fc5b  -

Other Versions

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

1.13.0,
1.12.3, 1.12.2, 1.12.1,
1.11.5, 1.11.4, 1.11.3, 1.11.2, 1.11.1, 1.11.0,
1.10.9, 1.10.8, 1.10.7, 1.10.6, 1.10.5, 1.10.4, 1.10.3, 1.10.2, 1.10.1, 1.10.0,
1.9.11, 1.9.10, 1.9.9, 1.9.8, 1.9.7, 1.9.6, 1.9.5, 1.9.4, 1.9.3, 1.9.2, 1.9.1, 1.9.0,
1.8.12, 1.8.11, 1.8.10, 1.8.9, 1.8.8, 1.8.7, 1.8.6, 1.8.5, 1.8.4, 1.8.3, 1.8.2, 1.8.1, 1.8.0,
1.7.10, 1.7.9, 1.7.8, 1.7.7, 1.7.6, 1.7.5, 1.7.4, 1.7.3, 1.7.2, 1.7.1, 1.7.0,
1.6.3, 1.6.2, 1.6.1, 1.6.0,
1.5.4, 1.5.3, 1.5.2, 1.5.1, 1.5.0,
1.4.6, 1.4.5, 1.4.4, 1.4.3, 1.4.2, 1.4.1, 1.4.0,
1.3.3, 1.3.2, 1.3.1, 1.3.0,
1.2.3

The project site contains an overview how well these versions were compressed.
Other interesting projects are AngularJS, BackboneJS, Bootstrap, D3, Ember, jQuery, Knockout, lodash, React, Socket.IO, ThreeJS, UnderscoreJS and Vue.

Changelog

Best Zopfli parameters so far:
Size Improvement Parameters Found
51887 bytes -3 bytes zopfli --i1000000 --mls8 --bsr15 --lazy --ohh June 13, 2016 @ 13:22
51890 bytes -1 byte zopfli --i100000 --mls8 --bsr15 --lazy --ohh June 10, 2016 @ 17:30
51891 bytes -9 bytes zopfli --i100000 --mls8 --bsr9 --lazy --ohh June 10, 2016 @ 09:58
51900 bytes -1 byte zopfli --i10000 --mls8 --bsr9 --lazy --ohh June 10, 2016 @ 08:57
51901 bytes -5 bytes zopfli --i10000 --mls16 --bsr15 --lazy --ohh June 10, 2016 @ 08:51
51906 bytes -4 bytes zopfli --i1000 --mls16 --bsr12 --lazy --ohh June 10, 2016 @ 08:41
51910 bytes zopfli --i100 --mls16 --bsr15 --lazy --ohh June 9, 2016 @ 17:48

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

Most recent activity on June 16, 2016 @ 14:38.

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
51908 51909 51905 51907 51907 51907 51903 51905 51902 51921 51922 51922 51924 51924 51924
51904 51911 51904 51901 51905 51918 51911 51911 51906 51917 51915 51914 51923 51916 51907
51916 51912 51914 51904 51904 51913 51905 51918 51908 51915 51913 51912 51918 51917 51908
51937 51910 51917 51901 51903 51909 51917 51901 51909 51908 51912 51911 51912 51911 51923
51912 51915 51901 51900 51902 51900 51902 51900 51917 51919 51913 51913 51911 51916 51918
51917 51913 51891 51900 51901 51904 51903 51909 51909 51918 51919 51914 51917 51911 51908
51904 51910 51901 51900 51902 51905 51903 51909 51908 51919 51915 51912 51920 51911 51921
51902 51912 51914 51900 51903 51901 51906 51900 51900 51916 51913 51912 51918 51916 51912
51904 51904 51901 51901 51901 51902 51920 51901 51908 51916 51911 51914 51921 51908 51918
51914 51912 51912 51901 51901 51914 51905 51903 51908 51915 51916 51919 51923 51917 51917
51901 51903 51900 51900 51903 51903 51903 51901 51902 51912 51913 51911 51918 51911 51913
51914 51912 51887 51901 51903 51912 51900 51904 51909 51915 51914 51912 51913 51923 51921
51910 51912 51911 51903 51901 51904 51902 51900 51908 51914 51907 51913 51918 51911 51912
51902 51911 51900 51904 51901 51904 51902 51903 51908 51922 51911 51912 51919 51912 51929
51912 51911 51911 51900 51900 51914 51903 51905 51908 51923 51906 51914 51918 51924 51918
51912 51912 51913 51903 51902 51904 51903 51909 51909 51916 51912 51910 51920 51911 51918
51903 51912 51903 51901 51900 51901 51901 51900 51910 51917 51913 51916 51918 51911 51917
51902 51904 51902 51901 51903 51902 51905 51910 51908 51917 51912 51912 51914 51911 51921
51909 51912 51901 51900 51900 51915 51906 51910 51908 51916 51906 51911 51914 51912 51923
51903 51911 51913 51902 51901 51909 51906 51900 51912 51919 51919 51912 51918 51910 51913
51912 51912 51911 51900 51902 51914 51902 51909 51908 51918 51908 51911 51915 51911 51916
51888 51905 51911 51901 51903 51900 51904 51910 51900 51917 51912 51912 51920 51912 51910
51913 51910 51901 51904 51903 51902 51906 51909 51900 51913 51912 51911 51918 51911 51913

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 51910 bytes 100%
1,000 51906 bytes -4 bytes 100%
10,000 51899 bytes -7 bytes 100%
100,000 51890 bytes -9 bytes 0.87%
1,000,000 51887 bytes -3 bytes 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
52055 bytes +168 bytes (+0.32%) +78 bytes
51977 bytes +90 bytes (+0.17%)
51978 bytes +91 bytes (+0.18%) +1 byte
52027 bytes +140 bytes (+0.27%) +50 bytes
52050 bytes +163 bytes (+0.31%) +73 bytes
52093 bytes +206 bytes (+0.40%) +116 bytes
52114 bytes +227 bytes (+0.44%) +137 bytes
52140 bytes +253 bytes (+0.49%) +163 bytes
52137 bytes +250 bytes (+0.48%) +160 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
ZPAQ (Wikipedia) zpaq zpaq -method 69 38267 bytes -13620 bytes (-26.25%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 45628 bytes -6259 bytes (-12.06%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 46494 bytes -5393 bytes (-10.39%)
Brotli (Wikipedia) brotli brotli -q 11 47875 bytes -4012 bytes (-7.73%)
LZMA2 (Wikipedia) xz xz -9 48988 bytes -2899 bytes (-5.59%)
ZSTD (Wikipedia) zstd zstd -19 50462 bytes -1425 bytes (-2.75%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 50752 bytes -1135 bytes (-2.19%)

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