Choose a version:
26% The original file has 610219 bytes (595.9k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 159225 bytes (155.5k, 26%).

After GZIP compression these minified files vary in size:
Boot
  63163 bytes (61.7k)
CDN, direct link
cdnhttps
  54829 bytes (53.5k)
CDN, direct link
cdnjs
  54750 bytes (53.5k)
CDN, direct link
gzip -6 (default)
  54489 bytes (53.2k)
local copy
gzip -9
  54423 bytes (53.1k)
local copy
libdeflate -12
  51866 bytes (50.7k)
local copy
7zip -mx=9 -tgzip
  51855 bytes (50.6k)
local copy
kzip -s0 -rn -b1
  51776 bytes (50.6k)
local copy
pigz -11 -n
  51776 bytes (50.6k)
local copy
Zopfli
  51598 bytes (50.4k)
local copy
Zopfli (defluff)
  51596 bytes (50.4k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/dojo/dojo-1.8.8.min.js

You will automatically get the smallest Dojo 1.8.8 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 3152 bytes by using my Dojo 1.8.8 Zopfli version instead of the best available CDN (6.11% smaller than cdnjs, 51598 vs. 54750 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 --bsr21 --lazy --ohh

(found December 3, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 2  --mls2
block splitting recursion 21  --bsr21
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 (51596 bytes).

Verify file integrity

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

MD5:
curl --silent --compressed http://download.dojotoolkit.org/release-1.8.8/dojo.js --location | md5sum
3838cdfd35ec9b905ff7bf1e996bd19b  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.8.8.min.zopfli.js.gz | md5sum
3838cdfd35ec9b905ff7bf1e996bd19b  -

SHA1:
curl --silent --compressed http://download.dojotoolkit.org/release-1.8.8/dojo.js --location | sha1sum
1b0f51b1da69713017d03ad2bf91a64136dcc815  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.8.8.min.zopfli.js.gz | sha1sum
1b0f51b1da69713017d03ad2bf91a64136dcc815  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 63163 bytes 3838cdfd35ec9b905ff7bf1e996bd19b March 19, 2015 @ 15:40
cdnjs 54750 bytes 3838cdfd35ec9b905ff7bf1e996bd19b February 8, 2015 @ 14:45

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
cdnhttps 54829 bytes 9c4dd8087e0aa46e25e980964acb6f69 < /*
< 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:

1.12.2, 1.12.1,
1.11.4, 1.11.3, 1.11.2, 1.11.1, 1.11.0,
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
51598 bytes -6 bytes zopfli --i100000 --mls2 --bsr21 --lazy --ohh December 3, 2015 @ 13:44
51604 bytes -2 bytes zopfli --i10000 --mls2 --bsr21 --lazy --ohh October 14, 2015 @ 03:46
51606 bytes -6 bytes zopfli --i1000 --mls2 --bsr21 --lazy --ohh September 22, 2015 @ 23:42
51612 bytes zopfli --i100 --mls2 --bsr21 --lazy --ohh September 22, 2015 @ 11:40

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
51683 51672 51681 51676 51680 51679 51676 51680 51680 51701 51688 51696 51704 51704 51685
51679 51630 51678 51680 51680 51677 51679 51679 51684 51670 51690 51690 51684 51682 51678
51622 51636 51631 51679 51677 51679 51682 51680 51679 51689 51681 51682 51682 51701 51681
51675 51709 51677 51678 51682 51679 51681 51680 51679 51678 51673 51683 51678 51676 51678
51615 51638 51698 51677 51678 51674 51673 51672 51681 51687 51692 51681 51682 51691 51679
51616 51629 51691 51678 51678 51679 51679 51674 51679 51693 51681 51689 51682 51684 51678
51621 51624 51679 51678 51679 51674 51680 51679 51679 51687 51685 51689 51699 51685 51679
51615 51631 51623 51677 51679 51674 51681 51675 51681 51687 51684 51682 51682 51684 51679
51617 51674 51677 51678 51678 51674 51674 51679 51695 51682 51681 51682 51682 51673 51681
51622 51633 51677 51678 51677 51678 51673 51678 51681 51683 51682 51682 51690 51681 51680
51615 51637 51677 51678 51678 51673 51674 51675 51681 51687 51684 51682 51689 51674 51678
51615 51629 51680 51675 51699 51679 51680 51684 51679 51698 51674 51690 51697 51677 51678
51622 51630 51678 51677 51677 51679 51680 51681 51696 51690 51687 51689 51703 51674 51681
51622 51634 51677 51678 51696 51678 51673 51678 51679 51684 51682 51685 51682 51672 51682
51618 51630 51680 51696 51679 51677 51682 51676 51682 51684 51688 51690 51698 51672 51682
51617 51627 51672 51674 51680 51681 51679 51674 51681 51685 51681 51682 51682 51676 51682
51616 51679 51672 51679 51680 51680 51673 51674 51679 51685 51687 51682 51698 51676 51678
51598 51632 51678 51679 51678 51674 51674 51674 51678 51685 51681 51683 51682 51702 51681
51614 51633 51676 51679 51679 51677 51682 51678 51682 51698 51691 51685 51682 51702 51679
51615 51680 51679 51677 51679 51674 51679 51681 51679 51690 51685 51683 51681 51680 51679
51616 51634 51680 51678 51678 51680 51681 51715 51678 51681 51674 51689 51686 51678 51681
51626 51624 51673 51677 51696 51673 51680 51679 51681 51676 51689 51682 51682 51681 51681
51616 51622 51676 51677 51678 51673 51673 51677 51679 51673 51673 51682 51682 51677 51678

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 51612 bytes 100%
1,000 51606 bytes -6 bytes 100%
10,000 51604 bytes -2 bytes 100%
100,000 51598 bytes -6 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
51838 bytes +240 bytes (+0.47%) +62 bytes
51776 bytes +178 bytes (+0.34%)
51788 bytes +190 bytes (+0.37%) +12 bytes
51838 bytes +240 bytes (+0.47%) +62 bytes
51865 bytes +267 bytes (+0.52%) +89 bytes
51877 bytes +279 bytes (+0.54%) +101 bytes
51929 bytes +331 bytes (+0.64%) +153 bytes
51910 bytes +312 bytes (+0.60%) +134 bytes
51928 bytes +330 bytes (+0.64%) +152 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 37834 bytes -13764 bytes (-26.68%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 44894 bytes -6704 bytes (-12.99%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 46262 bytes -5336 bytes (-10.34%)
Brotli (Wikipedia) brotli brotli -q 11 47328 bytes -4270 bytes (-8.28%)
LZMA2 (Wikipedia) xz xz -9 48480 bytes -3118 bytes (-6.04%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 49705 bytes -1893 bytes (-3.67%)
ZSTD (Wikipedia) zstd zstd -19 49919 bytes -1679 bytes (-3.25%)

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 2017.
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