Choose a version:
26% The original file has 610208 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 159226 bytes (155.5k, 26%).

After GZIP compression these minified files vary in size:
Boot
  63168 bytes (61.7k)
CDN, direct link
cdnhttps
  54830 bytes (53.5k)
CDN, direct link
cdnjs
  54753 bytes (53.5k)
CDN, direct link
gzip -6 (default)
  54495 bytes (53.2k)
local copy
gzip -9
  54428 bytes (53.2k)
local copy
libdeflate -12
  51868 bytes (50.7k)
local copy
7zip -mx=9 -tgzip
  51857 bytes (50.6k)
local copy
kzip -s0 -rn -b1
  51777 bytes (50.6k)
local copy
pigz -11 -n
  51769 bytes (50.6k)
local copy
Zopfli
  51598 bytes (50.4k)
local copy
Zopfli (defluff)
  51597 bytes (50.4k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/dojo/dojo-1.8.10.min.js

You will automatically get the smallest Dojo 1.8.10 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 3155 bytes by using my Dojo 1.8.10 Zopfli version instead of the best available CDN (6.11% smaller than cdnjs, 51598 vs. 54753 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 --mls8 --bsr19 --lazy --ohh

(found December 3, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 8  --mls8
block splitting recursion 19  --bsr19
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 (51597 bytes).

Verify file integrity

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

MD5:
curl --silent --compressed http://download.dojotoolkit.org/release-1.8.10/dojo.js --location | md5sum
686572db787d2b0939aa556d3e79db38  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.8.10.min.zopfli.js.gz | md5sum
686572db787d2b0939aa556d3e79db38  -

SHA1:
curl --silent --compressed http://download.dojotoolkit.org/release-1.8.10/dojo.js --location | sha1sum
5166b72ede6486d8fa9f98c0619deffabd56acd9  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.8.10.min.zopfli.js.gz | sha1sum
5166b72ede6486d8fa9f98c0619deffabd56acd9  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 63168 bytes 686572db787d2b0939aa556d3e79db38 March 19, 2015 @ 15:37
cdnjs 54753 bytes 686572db787d2b0939aa556d3e79db38 February 8, 2015 @ 14:45

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
cdnhttps 54830 bytes 9e9745a7aef5649828232a4cc084645b < /*
< 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 -8 bytes zopfli --i100000 --mls8 --bsr19 --lazy --ohh December 3, 2015 @ 15:00
51606 bytes -5 bytes zopfli --i10000 --mls8 --bsr19 --lazy --ohh November 23, 2015 @ 00:03
51611 bytes -1 byte zopfli --i10000 --mls8 --bsr25 --lazy --ohh October 14, 2015 @ 01:34
51612 bytes -4 bytes zopfli --i1000 --mls8 --bsr19 --lazy --ohh September 21, 2015 @ 18:55
51616 bytes zopfli --i100 --mls8 --bsr19 --lazy --ohh September 21, 2015 @ 11:32

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
51684 51673 51683 51678 51682 51679 51678 51682 51684 51703 51690 51697 51706 51706 51687
51681 51634 51680 51682 51683 51680 51681 51681 51686 51675 51691 51692 51685 51684 51680
51623 51638 51637 51681 51679 51681 51684 51682 51681 51691 51683 51684 51684 51705 51683
51677 51711 51679 51680 51683 51682 51683 51683 51680 51680 51675 51685 51680 51678 51680
51617 51644 51700 51679 51680 51675 51675 51674 51683 51689 51685 51683 51684 51692 51681
51618 51631 51692 51680 51680 51681 51682 51676 51681 51686 51684 51691 51684 51686 51680
51627 51629 51681 51680 51681 51676 51682 51680 51681 51688 51687 51724 51701 51687 51681
51617 51634 51624 51679 51681 51677 51682 51676 51685 51688 51685 51684 51684 51685 51680
51619 51709 51679 51680 51680 51675 51675 51681 51697 51684 51684 51684 51684 51675 51683
51622 51637 51679 51680 51679 51680 51674 51680 51683 51683 51675 51684 51692 51682 51682
51619 51638 51680 51680 51680 51675 51675 51677 51683 51687 51685 51684 51691 51675 51680
51618 51632 51623 51677 51701 51681 51682 51686 51680 51700 51675 51692 51700 51678 51680
51625 51631 51623 51678 51679 51681 51682 51683 51698 51692 51688 51692 51706 51676 51683
51623 51625 51623 51679 51698 51680 51674 51680 51681 51684 51684 51686 51684 51674 51684
51620 51632 51625 51697 51682 51679 51684 51677 51684 51689 51689 51725 51699 51674 51683
51620 51632 51598 51677 51682 51683 51681 51676 51683 51686 51684 51684 51684 51678 51683
51617 51681 51618 51681 51681 51681 51674 51677 51680 51689 51686 51684 51699 51678 51680
51618 51634 51624 51681 51680 51676 51676 51676 51680 51689 51683 51685 51683 51704 51684
51608 51635 51623 51681 51681 51679 51683 51680 51686 51701 51692 51687 51683 51704 51680
51618 51682 51680 51679 51680 51675 51681 51680 51680 51692 51687 51684 51683 51682 51681
51616 51634 51603 51680 51680 51681 51682 51676 51680 51685 51675 51724 51688 51680 51683
51628 51626 51674 51679 51698 51674 51681 51680 51684 51677 51691 51684 51684 51684 51683
51618 51625 51622 51679 51680 51675 51674 51678 51680 51677 51674 51684 51684 51679 51680

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 51616 bytes 100%
1,000 51612 bytes -4 bytes 100%
10,000 51606 bytes -6 bytes 100%
100,000 51598 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
51839 bytes +241 bytes (+0.47%) +62 bytes
51777 bytes +179 bytes (+0.35%)
51789 bytes +191 bytes (+0.37%) +12 bytes
51842 bytes +244 bytes (+0.47%) +65 bytes
51865 bytes +267 bytes (+0.52%) +88 bytes
51887 bytes +289 bytes (+0.56%) +110 bytes
51935 bytes +337 bytes (+0.65%) +158 bytes
51918 bytes +320 bytes (+0.62%) +141 bytes
51923 bytes +325 bytes (+0.63%) +146 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 37839 bytes -13759 bytes (-26.67%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 44895 bytes -6703 bytes (-12.99%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 46262 bytes -5336 bytes (-10.34%)
Brotli (Wikipedia) brotli brotli -q 11 47275 bytes -4323 bytes (-8.38%)
LZMA2 (Wikipedia) xz xz -9 48484 bytes -3114 bytes (-6.04%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 49803 bytes -1795 bytes (-3.48%)
ZSTD (Wikipedia) zstd zstd -19 49925 bytes -1673 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 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