Choose a version:
26% The original file has 613070 bytes (598.7k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 159460 bytes (155.7k, 26%).

After GZIP compression these minified files vary in size:
Boot
  63385 bytes (61.9k)
CDN
cdnhttps
  55028 bytes (53.7k)
CDN
cdnjs
  54929 bytes (53.6k)
CDN
gzip -6 (default)
  54689 bytes (53.4k)
local copy
gzip -9
  54634 bytes (53.4k)
local copy
jsdelivr
  54603 bytes (53.3k)
CDN
7zip -mx=9 -tgzip
  52042 bytes (50.8k)
local copy
libdeflate -12
  52041 bytes (50.8k)
local copy
pigz -11 -n
  52000 bytes (50.8k)
local copy
kzip -s0 -rn -b1
  51993 bytes (50.8k)
local copy
Zopfli
  51829 bytes (50.6k)
local copy
Zopfli (defluff)
  51827 bytes (50.6k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/dojo/dojo-1.9.1.min.js

You will automatically get the smallest Dojo 1.9.1 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 2774 bytes by using my Dojo 1.9.1 Zopfli version instead of the best available CDN (5.35% smaller than jsdelivr, 51829 vs. 54603 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 --mls4 --bsr4 --lazy --ohh

(found December 3, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 4  --mls4
block splitting recursion 4  --bsr4
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 2 more bytes (51827 bytes).

Verify file integrity

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

MD5:
curl --silent --compressed http://download.dojotoolkit.org/release-1.9.1/dojo.js --location | md5sum
67b90c46c842c4d23b095cedf6f80ad8  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.9.1.min.zopfli.js.gz | md5sum
67b90c46c842c4d23b095cedf6f80ad8  -

SHA1:
curl --silent --compressed http://download.dojotoolkit.org/release-1.9.1/dojo.js --location | sha1sum
a2f2bc8c9b103e113506ad4774223eb5a02d1214  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.9.1.min.zopfli.js.gz | sha1sum
a2f2bc8c9b103e113506ad4774223eb5a02d1214  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 63385 bytes 67b90c46c842c4d23b095cedf6f80ad8 March 19, 2015 @ 15:42
cdnjs 54929 bytes 67b90c46c842c4d23b095cedf6f80ad8 February 8, 2015 @ 14:45
jsdelivr 54603 bytes 67b90c46c842c4d23b095cedf6f80ad8 August 7, 2014 @ 19:16

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
cdnhttps 55028 bytes b528114d073d6951e47b86182b3bab57 < /*
< Copyright (c) 2004-2011, The Dojo Foundation All Rights R [...]
< Available via Academic Free License >= 2.1 OR the modifie [...]
< see: http://dojotoolkit.org/license for details
< */
<
< /*
< This is an optimized version of Dojo, built for deploymen [...]
< development. To get sources and documentation, please vis [...]
<
[...]
December 24, 2015 @ 07:33

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

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
51829 bytes -1 byte zopfli --i100000 --mls4 --bsr4 --lazy --ohh December 3, 2015 @ 19:21
51830 bytes -4 bytes zopfli --i100000 --mls8 --bsr12 --lazy --ohh December 3, 2015 @ 16:47
51834 bytes -1 byte zopfli --i10000 --mls8 --bsr12 --lazy --ohh October 13, 2015 @ 18:26
51835 bytes -2 bytes zopfli --i10000 --mls8 --bsr30 --lazy --ohh September 24, 2015 @ 14:13
51837 bytes -1 byte zopfli --i1000 --mls8 --bsr30 --lazy --ohh September 24, 2015 @ 13:26
51838 bytes -5 bytes zopfli --i1000 --mls8 --bsr12 --lazy --ohh September 19, 2015 @ 05:43
51843 bytes zopfli --i100 --mls8 --bsr12 --lazy --ohh September 18, 2015 @ 16:24

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 @ 14:37.

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
51909 51908 51908 51905 51908 51910 51907 51906 51916 51931 51926 51922 51922 51926 51946
51846 51829 51858 51910 51910 51907 51911 51908 51908 51912 51919 51917 51903 51904 51893
51860 51863 51852 51917 51906 51910 51909 51909 51907 51907 51920 51923 51911 51914 51903
51848 51903 51846 51908 51907 51906 51908 51909 51908 51917 51912 51916 51911 51904 51900
51856 51856 51909 51909 51901 51901 51909 51909 51917 51904 51903 51903 51911 51899 51914
51859 51855 51908 51909 51899 51900 51906 51907 51914 51918 51915 51918 51919 51895 51908
51857 51870 51843 51909 51907 51901 51906 51907 51909 51903 51904 51912 51910 51905 51904
51846 51854 51841 51915 51906 51901 51908 51911 51914 51906 51913 51918 51911 51915 51898
51858 51861 51830 51916 51901 51902 51908 51910 51909 51899 51903 51924 51912 51898 51899
51857 51846 51859 51908 51901 51901 51909 51910 51914 51913 51917 51917 51920 51903 51906
51857 51849 51908 51921 51905 51901 51908 51910 51911 51896 51910 51921 51911 51904 51898
51853 51860 51846 51907 51907 51902 51908 51910 51907 51899 51917 51919 51910 51895 51897
51853 51859 51844 51906 51902 51907 51911 51911 51911 51903 51914 51920 51919 51898 51905
51856 51858 51906 51921 51901 51906 51909 51901 51912 51906 51916 51917 51910 51896 51895
51857 51858 51918 51918 51902 51906 51908 51911 51911 51903 51909 51918 51925 51896 51898
51845 51865 51910 51917 51903 51901 51908 51909 51916 51916 51904 51901 51911 51898 51900
51855 51862 51910 51917 51903 51901 51908 51911 51906 51898 51912 51917 51910 51897 51900
51841 51857 51844 51907 51905 51901 51906 51909 51913 51897 51912 51917 51910 51900 51897
51849 51851 51906 51907 51902 51906 51908 51909 51912 51902 51903 51907 51910 51897 51903
51849 51860 51845 51917 51904 51908 51909 51907 51907 51903 51916 51919 51910 51903 51904
51853 51914 51908 51916 51900 51904 51908 51907 51912 51910 51912 51918 51919 51899 51899
51854 51856 51830 51907 51905 51901 51906 51909 51910 51916 51906 51908 51910 51901 51913
51842 51853 51847 51909 51900 51908 51908 51909 51908 51904 51920 51918 51913 51900 51906

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 51843 bytes 100%
1,000 51837 bytes -6 bytes 100%
10,000 51834 bytes -3 bytes 100%
100,000 51829 bytes -5 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
52048 bytes +219 bytes (+0.42%) +55 bytes
51993 bytes +164 bytes (+0.32%)
52005 bytes +176 bytes (+0.34%) +12 bytes
52047 bytes +218 bytes (+0.42%) +54 bytes
52070 bytes +241 bytes (+0.46%) +77 bytes
52086 bytes +257 bytes (+0.50%) +93 bytes
52128 bytes +299 bytes (+0.58%) +135 bytes
52137 bytes +308 bytes (+0.59%) +144 bytes
52143 bytes +314 bytes (+0.61%) +150 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 38015 bytes -13814 bytes (-26.65%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 45087 bytes -6742 bytes (-13.01%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 46481 bytes -5348 bytes (-10.32%)
Brotli (Wikipedia) brotli brotli -q 11 47562 bytes -4267 bytes (-8.23%)
LZMA2 (Wikipedia) xz xz -9 48700 bytes -3129 bytes (-6.04%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 50085 bytes -1744 bytes (-3.36%)
ZSTD (Wikipedia) zstd zstd -19 50171 bytes -1658 bytes (-3.20%)

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