Choose a version:
26% The original file has 598715 bytes (584.7k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 156294 bytes (152.6k, 26%).

After GZIP compression these minified files vary in size:
Boot
  61849 bytes (60.4k)
CDN
cdnhttps
  53775 bytes (52.5k)
CDN
Baidu
  53676 bytes (52.4k)
CDN
cdnjs
  53669 bytes (52.4k)
CDN
gzip -6 (default)
  53420 bytes (52.2k)
local copy
gzip -9
  53368 bytes (52.1k)
local copy
libdeflate -12
  50920 bytes (49.7k)
local copy
7zip -mx=9 -tgzip
  50860 bytes (49.7k)
local copy
kzip -s0 -rn -b1
  50775 bytes (49.6k)
local copy
pigz -11 -n
  50766 bytes (49.6k)
local copy
Zopfli
  50600 bytes (49.4k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/dojo/dojo-1.8.1.min.js (or via HTTPS)

You will automatically get the smallest Dojo 1.8.1 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 3069 bytes by using my Dojo 1.8.1 Zopfli version instead of the best available CDN (6.07% smaller than cdnjs, 50600 vs. 53669 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

Verify file integrity

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

MD5:
curl --silent --compressed https://download.dojotoolkit.org/release-1.8.1/dojo.js --location | md5sum
d3612e2d044837669c9660fe3299185c  -
curl --silent --compressed https://minime.stephan-brumme.com/files/dojo/dojo-1.8.1.min.zopfli.js.gz | md5sum
d3612e2d044837669c9660fe3299185c  -

SHA1:
curl --silent --compressed https://download.dojotoolkit.org/release-1.8.1/dojo.js --location | sha1sum
056dcd115645680eaf3d8b80113f443ecce48d9c  -
curl --silent --compressed https://minime.stephan-brumme.com/files/dojo/dojo-1.8.1.min.zopfli.js.gz | sha1sum
056dcd115645680eaf3d8b80113f443ecce48d9c  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 61849 bytes d3612e2d044837669c9660fe3299185c March 19, 2015 @ 15:37
cdnjs 53669 bytes d3612e2d044837669c9660fe3299185c January 13, 2014 @ 19:17

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
cdnhttps 53775 bytes 5bc932525400ce64de7c643b8398a3ac < /*
< 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
Baidu 53676 bytes be1ea434ca345e496254cd14c3c83464 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:

1.14.2, 1.14.1, 1.14.0,
1.13.3, 1.13.2, 1.13.1, 1.13.0,
1.12.4, 1.12.3, 1.12.2, 1.12.1,
1.11.6, 1.11.5, 1.11.4, 1.11.3, 1.11.2, 1.11.1, 1.11.0,
1.10.10, 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,
1.8.14, 1.8.13, 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,
1.7.12, 1.7.11, 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
50600 bytes -8 bytes zopfli --i100000 --mls4 --bsr4 --lazy --ohh December 3, 2015 @ 14:01
50608 bytes -4 bytes zopfli --i10000 --mls4 --bsr4 --lazy --ohh October 21, 2015 @ 13:40
50612 bytes -4 bytes zopfli --i1000 --mls4 --bsr4 --lazy --ohh September 21, 2015 @ 22:10
50616 bytes zopfli --i100 --mls4 --bsr4 --lazy --ohh September 21, 2015 @ 13:21

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 @ 14:39.

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
50647 50643 50675 50676 50676 50676 50676 50674 50699 50681 50670 50678 50709 50714 50674
50644 50600 50638 50671 50676 50681 50675 50679 50682 50685 50695 50671 50699 50680 50678
50650 50646 50631 50672 50677 50684 50674 50680 50684 50697 50692 50684 50696 50704 50674
50660 50630 50625 50638 50673 50671 50684 50681 50700 50688 50690 50686 50706 50676 50699
50661 50628 50633 50669 50685 50681 50679 50683 50689 50698 50696 50684 50693 50674 50690
50663 50636 50628 50668 50672 50677 50676 50679 50673 50670 50680 50696 50698 50688 50678
50624 50654 50627 50669 50671 50681 50681 50678 50672 50674 50687 50685 50695 50678 50679
50637 50628 50635 50700 50693 50681 50679 50679 50696 50670 50689 50682 50692 50681 50685
50634 50636 50629 50668 50672 50680 50680 50675 50702 50674 50691 50685 50697 50670 50691
50677 50667 50649 50668 50670 50680 50681 50677 50687 50677 50694 50686 50694 50681 50677
50649 50669 50636 50669 50697 50670 50678 50677 50677 50674 50695 50686 50693 50683 50677
50630 50625 50622 50645 50670 50671 50681 50681 50699 50693 50692 50684 50696 50678 50670
50709 50671 50632 50639 50670 50679 50687 50676 50695 50674 50695 50684 50696 50682 50687
50626 50625 50629 50672 50668 50670 50678 50687 50683 50685 50696 50682 50694 50677 50686
50631 50634 50620 50671 50672 50670 50680 50679 50672 50692 50695 50687 50698 50682 50686
50626 50673 50627 50671 50671 50671 50682 50678 50675 50683 50689 50682 50695 50681 50696
50636 50640 50628 50671 50669 50680 50687 50675 50674 50674 50696 50685 50695 50676 50678
50659 50626 50633 50671 50675 50670 50677 50680 50695 50687 50694 50685 50697 50674 50678
50634 50658 50631 50671 50670 50681 50680 50679 50694 50692 50695 50684 50695 50699 50679
50661 50664 50633 50670 50675 50683 50682 50673 50697 50694 50673 50685 50695 50668 50677
50666 50638 50633 50670 50671 50680 50687 50677 50673 50684 50695 50691 50699 50682 50677
50644 50627 50629 50669 50671 50680 50681 50678 50695 50677 50694 50693 50701 50672 50678
50635 50632 50629 50668 50673 50680 50680 50675 50685 50674 50694 50696 50696 50682 50678

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 50616 bytes 100%
1,000 50612 bytes -4 bytes 100%
10,000 50608 bytes -4 bytes 100%
100,000 50600 bytes -8 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
50827 bytes +227 bytes (+0.45%) +52 bytes
50775 bytes +175 bytes (+0.35%)
50794 bytes +194 bytes (+0.38%) +19 bytes
50824 bytes +224 bytes (+0.44%) +49 bytes
50865 bytes +265 bytes (+0.52%) +90 bytes
50879 bytes +279 bytes (+0.55%) +104 bytes
50871 bytes +271 bytes (+0.54%) +96 bytes
50872 bytes +272 bytes (+0.54%) +97 bytes
50861 bytes +261 bytes (+0.52%) +86 bytes

Non-DEFLATE Algorithms

Archivers based on completely different compression algorithms often produce superior results.
Unfortunately, browsers only support gzip compression at the moment.
However, support for Brotli is constantly growing - but your browser doesn't support it.
Algorithm Program Parameters Size Compared To Best Zopfli
ZPAQ (Wikipedia) zpaq zpaq -method 69 37290 bytes -13310 bytes (-26.30%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 44145 bytes -6455 bytes (-12.76%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 45441 bytes -5159 bytes (-10.20%)
Brotli (Wikipedia) brotli brotli -q 11 46519 bytes -4081 bytes (-8.07%)
LZMA2 (Wikipedia) xz xz -9 47636 bytes -2964 bytes (-5.86%)
Zstandard (Wikipedia) zstd zstd -19 49088 bytes -1512 bytes (-2.99%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 49112 bytes -1488 bytes (-2.94%)

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