Choose a version:
26% The original file has 621725 bytes (607.2k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 161277 bytes (157.5k, 26%).

After GZIP compression these minified files vary in size:
Boot
  64014 bytes (62.5k)
CDN
cdnhttps
  55589 bytes (54.3k)
CDN
cdnjs
  55473 bytes (54.2k)
CDN
gzip -6 (default)
  55216 bytes (53.9k)
local copy
gzip -9
  55163 bytes (53.9k)
local copy
libdeflate -12
  52572 bytes (51.3k)
local copy
7zip -mx=9 -tgzip
  52552 bytes (51.3k)
local copy
pigz -11 -n
  52506 bytes (51.3k)
local copy
kzip -s0 -rn -b1
  52499 bytes (51.3k)
local copy
Zopfli
  52322 bytes (51.1k)
local copy
Zopfli (defluff)
  52320 bytes (51.1k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/dojo/dojo-1.9.6.min.js

You will automatically get the smallest Dojo 1.9.6 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 3151 bytes by using my Dojo 1.9.6 Zopfli version instead of the best available CDN (6.02% smaller than cdnjs, 52322 vs. 55473 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 --bsr8 --lazy --ohh

(found December 3, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 8  --mls8
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 2 more bytes (52320 bytes).

Verify file integrity

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

MD5:
curl --silent --compressed http://download.dojotoolkit.org/release-1.9.6/dojo.js --location | md5sum
117892259651691374d84eae4b49920a  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.9.6.min.zopfli.js.gz | md5sum
117892259651691374d84eae4b49920a  -

SHA1:
curl --silent --compressed http://download.dojotoolkit.org/release-1.9.6/dojo.js --location | sha1sum
259de508408d0373429cb2afb9a09ac993069918  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.9.6.min.zopfli.js.gz | sha1sum
259de508408d0373429cb2afb9a09ac993069918  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 64014 bytes 117892259651691374d84eae4b49920a March 19, 2015 @ 15:44
cdnjs 55473 bytes 117892259651691374d84eae4b49920a February 8, 2015 @ 14:45

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
cdnhttps 55589 bytes f3f45544c070c1ae79e0a55b7cab1a19 < /*
< Copyright (c) 2004-2011, 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
52322 bytes -1 byte zopfli --i100000 --mls8 --bsr8 --lazy --ohh December 3, 2015 @ 21:18
52323 bytes -2 bytes zopfli --i100000 --mls8 --bsr15 --lazy --ohh December 3, 2015 @ 20:18
52325 bytes -2 bytes zopfli --i100000 --mls8 --bsr13 --lazy --ohh December 3, 2015 @ 19:01
52327 bytes -2 bytes zopfli --i10000 --mls8 --bsr13 --lazy --ohh October 13, 2015 @ 21:42
52329 bytes -2 bytes zopfli --i10000 --mls8 --bsr15 --lazy --ohh October 13, 2015 @ 20:14
52331 bytes -1 byte zopfli --i1000 --mls8 --bsr13 --lazy --ohh September 18, 2015 @ 23:53
52332 bytes -5 bytes zopfli --i1000 --mls8 --bsr8 --lazy --ohh September 18, 2015 @ 23:51
52337 bytes zopfli --i100 --mls8 --bsr13 --lazy --ohh September 18, 2015 @ 16:13

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
52403 52400 52398 52402 52404 52403 52400 52401 52401 52418 52398 52421 52427 52418 52401
52361 52350 52342 52395 52411 52404 52415 52407 52405 52401 52407 52418 52419 52406 52402
52353 52346 52359 52395 52395 52404 52399 52398 52402 52400 52410 52420 52415 52414 52404
52396 52395 52332 52395 52396 52403 52402 52414 52404 52401 52411 52417 52418 52411 52402
52341 52336 52322 52397 52395 52397 52401 52394 52400 52413 52410 52418 52407 52400 52407
52344 52341 52354 52395 52395 52397 52400 52396 52405 52410 52403 52418 52415 52411 52405
52358 52360 52353 52395 52399 52394 52396 52398 52402 52403 52406 52420 52414 52418 52405
52344 52344 52356 52397 52396 52394 52398 52399 52405 52400 52413 52418 52418 52396 52404
52342 52341 52340 52395 52395 52397 52396 52399 52400 52398 52411 52403 52415 52396 52413
52341 52339 52325 52395 52395 52397 52396 52394 52400 52398 52397 52417 52414 52406 52403
52343 52337 52416 52396 52397 52395 52396 52396 52403 52395 52409 52408 52415 52408 52405
52341 52338 52323 52404 52395 52394 52396 52406 52400 52397 52411 52416 52417 52400 52404
52335 52341 52330 52394 52395 52397 52401 52401 52400 52401 52401 52417 52414 52402 52403
52346 52342 52419 52397 52395 52397 52398 52396 52399 52409 52411 52416 52418 52397 52404
52347 52349 52341 52396 52397 52394 52400 52398 52398 52393 52403 52417 52417 52395 52404
52344 52396 52396 52395 52396 52397 52403 52395 52401 52394 52412 52417 52416 52400 52404
52340 52340 52356 52396 52398 52397 52396 52400 52405 52394 52411 52416 52417 52417 52403
52344 52343 52350 52396 52394 52396 52397 52396 52398 52410 52403 52417 52414 52400 52403
52349 52341 52340 52396 52397 52396 52400 52398 52402 52409 52397 52418 52418 52412 52409
52339 52337 52355 52395 52400 52396 52401 52396 52400 52410 52412 52416 52416 52409 52404
52348 52344 52352 52395 52396 52396 52400 52408 52404 52399 52408 52417 52415 52399 52404
52338 52342 52351 52394 52398 52397 52400 52398 52404 52410 52410 52416 52414 52400 52405
52342 52341 52340 52395 52395 52396 52396 52398 52405 52414 52410 52417 52414 52398 52406

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 52337 bytes 100%
1,000 52331 bytes -6 bytes 100%
10,000 52327 bytes -4 bytes 100%
100,000 52322 bytes -5 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
52559 bytes +237 bytes (+0.45%) +60 bytes
52499 bytes +177 bytes (+0.34%)
52518 bytes +196 bytes (+0.37%) +19 bytes
52562 bytes +240 bytes (+0.46%) +63 bytes
52595 bytes +273 bytes (+0.52%) +96 bytes
52613 bytes +291 bytes (+0.56%) +114 bytes
52620 bytes +298 bytes (+0.57%) +121 bytes
52656 bytes +334 bytes (+0.64%) +157 bytes
52667 bytes +345 bytes (+0.66%) +168 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 38445 bytes -13877 bytes (-26.52%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 45531 bytes -6791 bytes (-12.98%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 46852 bytes -5470 bytes (-10.45%)
Brotli (Wikipedia) brotli brotli -q 11 47962 bytes -4360 bytes (-8.33%)
LZMA2 (Wikipedia) xz xz -9 49116 bytes -3206 bytes (-6.13%)
ZSTD (Wikipedia) zstd zstd -19 50590 bytes -1732 bytes (-3.31%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 50602 bytes -1720 bytes (-3.29%)

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