Choose a version:
24% The original file has 377726 bytes (368.9k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 90555 bytes (88.4k, 24%).

After GZIP compression these minified files vary in size:
Boot
  35499 bytes (34.7k)
CDN, direct link
cdnhttps
  31026 bytes (30.3k)
CDN, direct link
cdnjs
  30976 bytes (30.3k)
CDN, direct link
gzip -6 (default)
  30882 bytes (30.2k)
local copy
gzip -9
  30845 bytes (30.1k)
local copy
Yandex
  30830 bytes (30.1k)
CDN, direct link
libdeflate -12
  29487 bytes (28.8k)
local copy
7zip -mx=9 -tgzip
  29477 bytes (28.8k)
local copy
kzip -s0 -rn -b0
  29449 bytes (28.8k)
local copy
pigz -11 -n
  29417 bytes (28.7k)
local copy
Zopfli
  29344 bytes (28.7k)
local copy
Zopfli (defluff)
  29343 bytes (28.7k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/dojo/dojo-1.5.2.min.js

You will automatically get the smallest Dojo 1.5.2 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 1486 bytes by using my Dojo 1.5.2 Zopfli version instead of the best available CDN (5.06% smaller than Yandex, 29344 vs. 30830 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 --mls16 --bsr22 --lazy --ohh

(found December 2, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 16  --mls16
block splitting recursion 22  --bsr22
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 (29343 bytes).

Verify file integrity

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

MD5:
curl --silent --compressed http://download.dojotoolkit.org/release-1.5.2/dojo.js --location | md5sum
eb457dd8da0818e3365419e35ede4cfd  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.5.2.min.zopfli.js.gz | md5sum
eb457dd8da0818e3365419e35ede4cfd  -

SHA1:
curl --silent --compressed http://download.dojotoolkit.org/release-1.5.2/dojo.js --location | sha1sum
fc20c4f93969ad97f9db897bf0d41e2901346562  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.5.2.min.zopfli.js.gz | sha1sum
fc20c4f93969ad97f9db897bf0d41e2901346562  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 35499 bytes eb457dd8da0818e3365419e35ede4cfd March 19, 2015 @ 15:32
cdnjs 30976 bytes eb457dd8da0818e3365419e35ede4cfd February 8, 2015 @ 14:45
Yandex 30830 bytes eb457dd8da0818e3365419e35ede4cfd June 20, 2013 @ 11:59

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
cdnhttps 31026 bytes 581cb254a58e5f447a819f66634c3d57 < /*
< Copyright (c) 2004-2010, 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
29344 bytes -3 bytes zopfli --i100000 --mls16 --bsr22 --lazy --ohh December 2, 2015 @ 09:40
29347 bytes -3 bytes zopfli --i10000 --mls16 --bsr22 --lazy --ohh November 22, 2015 @ 22:15
29350 bytes -4 bytes zopfli --i1000 --mls16 --bsr22 --lazy --ohh September 22, 2015 @ 02:49
29354 bytes -7 bytes zopfli --i1000 --mls8192 --bsr11 --lazy --ohh September 11, 2015 @ 00:00
29361 bytes zopfli --i100 --mls8192 --bsr11 --lazy --ohh September 10, 2015 @ 15:17

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
29377 29381 29385 29398 29400 29369 29402 29391 29400 29413 29411 29424 29407 29413 29402
29395 29406 29386 29373 29390 29390 29363 29397 29377 29398 29406 29405 29394 29410 29409
29377 29390 29367 29382 29369 29376 29377 29404 29370 29401 29400 29399 29397 29413 29406
29391 29386 29369 29384 29377 29372 29355 29402 29373 29403 29362 29408 29401 29403 29406
29389 29386 29381 29383 29382 29371 29415 29399 29372 29406 29392 29399 29398 29404 29399
29384 29368 29380 29376 29376 29381 29388 29380 29378 29407 29393 29405 29366 29409 29405
29379 29364 29368 29379 29382 29383 29403 29397 29401 29397 29395 29403 29371 29413 29411
29371 29397 29372 29378 29378 29375 29380 29398 29378 29402 29394 29393 29347 29407 29396
29388 29385 29379 29382 29374 29369 29377 29402 29372 29395 29405 29406 29397 29411 29406
29373 29374 29370 29354 29380 29377 29355 29388 29363 29395 29393 29406 29402 29405 29402
29377 29376 29372 29374 29382 29375 29374 29394 29382 29395 29395 29397 29401 29405 29406
29379 29374 29373 29375 29395 29367 29374 29380 29377 29396 29392 29406 29379 29402 29405
29378 29379 29369 29377 29383 29379 29374 29403 29375 29395 29401 29407 29379 29407 29402
29375 29384 29383 29383 29379 29377 29378 29399 29377 29408 29399 29405 29393 29402 29401
29378 29389 29379 29372 29375 29377 29376 29383 29372 29401 29402 29406 29396 29406 29405
29377 29389 29355 29375 29376 29375 29400 29374 29377 29398 29396 29405 29396 29405 29402
29384 29385 29375 29377 29355 29377 29386 29386 29374 29400 29381 29406 29397 29407 29407
29390 29386 29365 29381 29388 29381 29399 29392 29375 29400 29396 29393 29395 29405 29406
29376 29383 29364 29344 29378 29382 29376 29402 29372 29400 29401 29397 29397 29406 29402
29383 29377 29378 29384 29370 29379 29372 29382 29372 29393 29397 29406 29398 29403 29406
29383 29380 29379 29352 29374 29366 29398 29403 29372 29394 29396 29407 29398 29409 29402
29361 29387 29378 29383 29374 29376 29398 29400 29399 29397 29385 29394 29393 29406 29400
29378 29383 29378 29381 29378 29371 29400 29382 29353 29395 29384 29408 29370 29413 29406

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 29358 bytes 100%
1,000 29350 bytes -8 bytes 100%
10,000 29347 bytes -3 bytes 100%
100,000 29344 bytes -3 bytes 0.58%
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
29449 bytes +105 bytes (+0.36%)
29460 bytes +116 bytes (+0.40%) +11 bytes
29492 bytes +148 bytes (+0.50%) +43 bytes
29453 bytes +109 bytes (+0.37%) +4 bytes
29496 bytes +152 bytes (+0.52%) +47 bytes
29486 bytes +142 bytes (+0.48%) +37 bytes
29496 bytes +152 bytes (+0.52%) +47 bytes
29469 bytes +125 bytes (+0.43%) +20 bytes
29507 bytes +163 bytes (+0.56%) +58 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 23227 bytes -6117 bytes (-20.85%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 26180 bytes -3164 bytes (-10.78%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 27096 bytes -2248 bytes (-7.66%)
Brotli (Wikipedia) brotli brotli -q 11 27203 bytes -2141 bytes (-7.30%)
LZMA2 (Wikipedia) xz xz -9 28116 bytes -1228 bytes (-4.18%)
ZSTD (Wikipedia) zstd zstd -19 28911 bytes -433 bytes (-1.48%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 29005 bytes -339 bytes (-1.16%)

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