Choose a version:
26% The original file has 609972 bytes (595.7k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 159258 bytes (155.5k, 26%).

After GZIP compression these minified files vary in size:
Boot
  63163 bytes (61.7k)
CDN
cdnhttps
  54833 bytes (53.5k)
CDN
cdnjs
  54754 bytes (53.5k)
CDN
gzip -6 (default)
  54496 bytes (53.2k)
local copy
gzip -9
  54428 bytes (53.2k)
local copy
libdeflate -12
  51870 bytes (50.7k)
local copy
7zip -mx=9 -tgzip
  51858 bytes (50.6k)
local copy
pigz -11 -n
  51781 bytes (50.6k)
local copy
kzip -s0 -rn -b1
  51779 bytes (50.6k)
local copy
Zopfli
  51601 bytes (50.4k)
local copy
Zopfli (defluff)
  51600 bytes (50.4k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/dojo/dojo-1.8.7.min.js

You will automatically get the smallest Dojo 1.8.7 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 3153 bytes by using my Dojo 1.8.7 Zopfli version instead of the best available CDN (6.11% smaller than cdnjs, 51601 vs. 54754 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 --mls2 --bsr8 --lazy --ohh

(found December 3, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 2  --mls2
block splitting recursion 8  --bsr8
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 (51600 bytes).

Verify file integrity

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

MD5:
curl --silent --compressed http://download.dojotoolkit.org/release-1.8.7/dojo.js --location | md5sum
19561dca0ddfc2a454bc7491658629d8  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.8.7.min.zopfli.js.gz | md5sum
19561dca0ddfc2a454bc7491658629d8  -

SHA1:
curl --silent --compressed http://download.dojotoolkit.org/release-1.8.7/dojo.js --location | sha1sum
a7370a3f5a352e21cb601ec50d1f76592d98f330  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.8.7.min.zopfli.js.gz | sha1sum
a7370a3f5a352e21cb601ec50d1f76592d98f330  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 63163 bytes 19561dca0ddfc2a454bc7491658629d8 March 19, 2015 @ 15:40
cdnjs 54754 bytes 19561dca0ddfc2a454bc7491658629d8 February 8, 2015 @ 14:45

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
cdnhttps 54833 bytes 1d85e996d6655a88ed0bbe28274aef30 < /*
< Copyright (c) 2004-2012, 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
51601 bytes -2 bytes zopfli --i100000 --mls2 --bsr8 --lazy --ohh December 3, 2015 @ 12:57
51603 bytes -7 bytes zopfli --i100000 --mls8 --bsr6 --lazy --ohh December 3, 2015 @ 12:12
51610 bytes -3 bytes zopfli --i10000 --mls2 --bsr8 --lazy --ohh October 13, 2015 @ 23:11
51613 bytes -1 byte zopfli --i1000 --mls2 --bsr7 --lazy --ohh September 23, 2015 @ 00:29
51614 bytes -3 bytes zopfli --i1000 --mls8 --bsr6 --lazy --ohh September 19, 2015 @ 10:34
51617 bytes -2 bytes zopfli --i1000 --mls8 --bsr13 --lazy --ohh September 19, 2015 @ 10:30
51619 bytes zopfli --i100 --mls8 --bsr6 --lazy --ohh September 18, 2015 @ 15:57

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
51689 51678 51686 51681 51683 51682 51681 51686 51687 51706 51693 51700 51710 51710 51691
51684 51636 51647 51680 51686 51684 51684 51685 51690 51676 51687 51696 51689 51689 51685
51620 51642 51603 51680 51683 51685 51688 51686 51685 51694 51687 51687 51687 51706 51687
51601 51680 51719 51684 51688 51685 51686 51687 51684 51684 51678 51689 51684 51680 51684
51601 51624 51692 51683 51683 51679 51679 51678 51687 51693 51689 51686 51687 51696 51686
51622 51640 51697 51679 51684 51685 51685 51681 51684 51698 51688 51695 51687 51681 51685
51626 51633 51679 51683 51686 51683 51686 51684 51684 51692 51690 51694 51702 51686 51685
51622 51630 51680 51678 51684 51680 51686 51681 51690 51695 51689 51688 51688 51690 51684
51623 51612 51694 51707 51684 51679 51679 51684 51702 51687 51688 51687 51687 51678 51687
51627 51638 51616 51680 51684 51684 51678 51684 51687 51687 51688 51688 51696 51688 51684
51622 51643 51628 51679 51684 51679 51679 51681 51685 51693 51687 51687 51695 51688 51684
51621 51627 51679 51679 51711 51685 51685 51689 51684 51705 51680 51695 51703 51680 51685
51629 51625 51620 51682 51684 51684 51686 51686 51702 51695 51692 51695 51709 51682 51687
51628 51639 51694 51683 51707 51684 51678 51684 51684 51687 51687 51690 51687 51677 51687
51624 51626 51694 51704 51685 51683 51688 51682 51687 51690 51695 51695 51702 51676 51687
51623 51633 51695 51681 51686 51688 51684 51681 51687 51690 51688 51688 51687 51682 51687
51621 51631 51602 51681 51682 51686 51678 51681 51684 51691 51687 51688 51702 51680 51684
51622 51626 51694 51684 51684 51680 51680 51680 51684 51691 51687 51688 51687 51708 51687
51619 51628 51624 51684 51685 51683 51687 51683 51690 51704 51696 51690 51687 51710 51684
51623 51631 51688 51680 51711 51680 51684 51687 51685 51696 51691 51688 51686 51689 51684
51622 51625 51627 51683 51711 51686 51685 51681 51684 51688 51680 51694 51687 51684 51686
51621 51630 51679 51683 51686 51679 51685 51685 51688 51680 51695 51688 51703 51681 51687
51622 51628 51698 51680 51684 51679 51678 51683 51684 51693 51678 51687 51688 51683 51684

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 51619 bytes 100%
1,000 51613 bytes -6 bytes 100%
10,000 51610 bytes -3 bytes 100%
100,000 51601 bytes -9 bytes 1.16%
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
51845 bytes +244 bytes (+0.47%) +66 bytes
51779 bytes +178 bytes (+0.34%)
51798 bytes +197 bytes (+0.38%) +19 bytes
51843 bytes +242 bytes (+0.47%) +64 bytes
51870 bytes +269 bytes (+0.52%) +91 bytes
51889 bytes +288 bytes (+0.56%) +110 bytes
51932 bytes +331 bytes (+0.64%) +153 bytes
51919 bytes +318 bytes (+0.62%) +140 bytes
51935 bytes +334 bytes (+0.65%) +156 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 37840 bytes -13761 bytes (-26.67%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 44899 bytes -6702 bytes (-12.99%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 46266 bytes -5335 bytes (-10.34%)
Brotli (Wikipedia) brotli brotli -q 11 47342 bytes -4259 bytes (-8.25%)
LZMA2 (Wikipedia) xz xz -9 48480 bytes -3121 bytes (-6.05%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 49807 bytes -1794 bytes (-3.48%)
ZSTD (Wikipedia) zstd zstd -19 49927 bytes -1674 bytes (-3.24%)

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