Choose a version:
24% The original file has 375083 bytes (366.3k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 89264 bytes (87.2k, 24%).

After GZIP compression these minified files vary in size:
Boot
  35014 bytes (34.2k)
CDN
cdnhttps
  30545 bytes (29.8k)
CDN
Baidu
  30529 bytes (29.8k)
CDN
cdnjs
  30517 bytes (29.8k)
CDN
gzip -6 (default)
  30420 bytes (29.7k)
local copy
gzip -9
  30382 bytes (29.7k)
local copy
Yandex
  30367 bytes (29.7k)
CDN
libdeflate -12
  29062 bytes (28.4k)
local copy
7zip -mx=9 -tgzip
  29020 bytes (28.3k)
local copy
kzip -s0 -rn -b0
  29001 bytes (28.3k)
local copy
pigz -11 -n
  28933 bytes (28.3k)
local copy
Zopfli
  28862 bytes (28.2k)
local copy
Zopfli (defluff)
  28861 bytes (28.2k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/dojo/dojo-1.4.0.min.js

You will automatically get the smallest Dojo 1.4.0 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 1505 bytes by using my Dojo 1.4.0 Zopfli version instead of the best available CDN (5.21% smaller than Yandex, 28862 vs. 30367 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 --mls16 --bsr22 --lazy --ohh

(found December 1, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 16  --mls16
block splitting recursion 22  --bsr22
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 (28861 bytes).

Verify file integrity

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

MD5:
curl --silent --compressed http://download.dojotoolkit.org/release-1.4.0/dojo.js --location | md5sum
8f2918241b7c6c7530956d8ed74537a7  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.4.0.min.zopfli.js.gz | md5sum
8f2918241b7c6c7530956d8ed74537a7  -

SHA1:
curl --silent --compressed http://download.dojotoolkit.org/release-1.4.0/dojo.js --location | sha1sum
c8c84eddc732c3cbf370764836a7712f3f873326  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.4.0.min.zopfli.js.gz | sha1sum
c8c84eddc732c3cbf370764836a7712f3f873326  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 35014 bytes 8f2918241b7c6c7530956d8ed74537a7 March 19, 2015 @ 15:30
cdnjs 30517 bytes 8f2918241b7c6c7530956d8ed74537a7 February 8, 2015 @ 14:45
Yandex 30367 bytes 8f2918241b7c6c7530956d8ed74537a7 June 20, 2013 @ 11:59

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
cdnhttps 30545 bytes 27f173591451bdae59e9a7b3cd4a5b2b < /*
< Copyright (c) 2004-2009, 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 a compiled version of Dojo, built for deployment [...]
< development. To get an editable version, please visit:
<
[...]
December 24, 2015 @ 07:33
Baidu 30529 bytes affef347e2bc428b8e2c3a297b3c1014 only whitespaces differ January 7, 2015 @ 10:16

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
28862 bytes -2 bytes zopfli --i100000 --mls16 --bsr22 --lazy --ohh December 1, 2015 @ 15:08
28864 bytes -6 bytes zopfli --i10000 --mls16 --bsr22 --lazy --ohh November 22, 2015 @ 22:10
28870 bytes -7 bytes zopfli --i1000 --mls16 --bsr22 --lazy --ohh September 22, 2015 @ 05:00
28877 bytes zopfli --i100 --mls16 --bsr22 --lazy --ohh September 21, 2015 @ 11:54

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 @ 14:40.

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
28931 28940 28945 28945 28939 28964 28952 28951 28958 28955 28955 28907 28964 28953 28952
28919 28941 28913 28944 28920 28910 28903 28922 28924 28921 28909 28954 28952 28955 28958
28915 28914 28914 28913 28920 28909 28922 28912 28928 28917 28920 28957 28966 28954 28954
28917 28933 28931 28916 28916 28916 28925 28916 28944 28947 28944 28956 28953 28953 28949
28939 28907 28930 28912 28923 28921 28912 28921 28929 28917 28917 28900 28954 28952 28952
28933 28920 28917 28924 28921 28913 28926 28903 28918 28925 28927 28953 28910 28947 28949
28920 28936 28921 28924 28906 28905 28923 28938 28913 28950 28911 28953 28909 28954 28950
28922 28931 28914 28902 28919 28914 28905 28914 28923 28948 28916 28948 28895 28945 28950
28922 28911 28917 28925 28911 28911 28915 28923 28919 28904 28923 28942 28952 28949 28954
28918 28907 28913 28901 28902 28911 28904 28919 28922 28945 28914 28883 28948 28946 28946
28919 28905 28901 28904 28911 28904 28907 28917 28925 28909 28916 28954 28897 28949 28950
28916 28905 28910 28910 28908 28908 28912 28915 28921 28903 28919 28955 28898 28951 28951
28908 28908 28899 28909 28918 28906 28909 28920 28908 28915 28898 28948 28961 28954 28951
28925 28913 28893 28911 28920 28904 28914 28913 28932 28910 28920 28947 28924 28952 28952
28930 28892 28896 28913 28884 28923 28918 28925 28939 28911 28917 28948 28949 28950 28950
28928 28920 28927 28908 28905 28921 28914 28905 28944 28923 28950 28949 28935 28951 28951
28889 28892 28896 28889 28896 28925 28915 28921 28908 28953 28922 28949 28891 28956 28947
28921 28910 28909 28910 28918 28897 28913 28906 28918 28911 28921 28946 28934 28952 28956
28891 28892 28926 28862 28907 28921 28917 28922 28911 28926 28912 28955 28900 28955 28953
28920 28905 28906 28903 28905 28910 28914 28914 28912 28906 28923 28955 28899 28945 28946
28917 28901 28934 28907 28908 28912 28914 28923 28920 28904 28908 28895 28896 28951 28951
28916 28927 28914 28905 28905 28914 28915 28930 28920 28906 28916 28948 28893 28954 28946
28918 28906 28930 28910 28906 28911 28913 28923 28931 28904 28916 28957 28964 28952 28952

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 28877 bytes 100%
1,000 28870 bytes -7 bytes 100%
10,000 28864 bytes -6 bytes 100%
100,000 28862 bytes -2 bytes 0.29%
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
29001 bytes +139 bytes (+0.48%)
29008 bytes +146 bytes (+0.51%) +7 bytes
29045 bytes +183 bytes (+0.63%) +44 bytes
29016 bytes +154 bytes (+0.53%) +15 bytes
29038 bytes +176 bytes (+0.61%) +37 bytes
29028 bytes +166 bytes (+0.58%) +27 bytes
29022 bytes +160 bytes (+0.55%) +21 bytes
29028 bytes +166 bytes (+0.58%) +27 bytes
29071 bytes +209 bytes (+0.72%) +70 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 22984 bytes -5878 bytes (-20.37%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 25764 bytes -3098 bytes (-10.73%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 26620 bytes -2242 bytes (-7.77%)
Brotli (Wikipedia) brotli brotli -q 11 26825 bytes -2037 bytes (-7.06%)
LZMA2 (Wikipedia) xz xz -9 27704 bytes -1158 bytes (-4.01%)
ZSTD (Wikipedia) zstd zstd -19 28459 bytes -403 bytes (-1.40%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 28576 bytes -286 bytes (-0.99%)

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