Choose a version:
24% The original file has 377569 bytes (368.7k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 90550 bytes (88.4k, 24%).

After GZIP compression these minified files vary in size:
Boot
  35491 bytes (34.7k)
CDN
cdnhttps
  31024 bytes (30.3k)
CDN
cdnjs
  30979 bytes (30.3k)
CDN
gzip -6 (default)
  30880 bytes (30.2k)
local copy
gzip -9
  30840 bytes (30.1k)
local copy
libdeflate -12
  29482 bytes (28.8k)
local copy
7zip -mx=9 -tgzip
  29470 bytes (28.8k)
local copy
kzip -s0 -rn -b4
  29434 bytes (28.7k)
local copy
pigz -11 -n
  29405 bytes (28.7k)
local copy
Zopfli
  29320 bytes (28.6k)
local copy
Zopfli (defluff)
  29319 bytes (28.6k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/dojo/dojo-1.5.4.min.js

You will automatically get the smallest Dojo 1.5.4 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 1659 bytes by using my Dojo 1.5.4 Zopfli version instead of the best available CDN (5.66% smaller than cdnjs, 29320 vs. 30979 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 --bsr22 --lazy --ohh

(found December 2, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 2  --mls2
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 (29319 bytes).

Verify file integrity

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

MD5:
curl --silent --compressed http://download.dojotoolkit.org/release-1.5.4/dojo.js --location | md5sum
4abcba1a57166873cee80849e7477a09  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.5.4.min.zopfli.js.gz | md5sum
4abcba1a57166873cee80849e7477a09  -

SHA1:
curl --silent --compressed http://download.dojotoolkit.org/release-1.5.4/dojo.js --location | sha1sum
c74b312c92294c853bc438397637c6bbb334a73d  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.5.4.min.zopfli.js.gz | sha1sum
c74b312c92294c853bc438397637c6bbb334a73d  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 35491 bytes 4abcba1a57166873cee80849e7477a09 March 19, 2015 @ 15:32
cdnjs 30979 bytes 4abcba1a57166873cee80849e7477a09 February 8, 2015 @ 14:45

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
cdnhttps 31024 bytes a6ff3b38d0fd0f9e3261f8e71cd1f73a < /*
< 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:

1.13.0,
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
29320 bytes -2 bytes zopfli --i100000 --mls2 --bsr22 --lazy --ohh December 2, 2015 @ 10:20
29322 bytes -5 bytes zopfli --i10000 --mls2 --bsr22 --lazy --ohh November 22, 2015 @ 22:17
29327 bytes -6 bytes zopfli --i1000 --mls2 --bsr22 --lazy --ohh September 23, 2015 @ 16:14
29333 bytes zopfli --i100 --mls2 --bsr22 --lazy --ohh September 22, 2015 @ 10:51

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
29369 29365 29367 29377 29397 29385 29388 29376 29399 29403 29398 29391 29394 29406 29397
29380 29389 29379 29373 29366 29382 29351 29392 29356 29389 29388 29395 29348 29390 29396
29347 29382 29364 29373 29359 29380 29354 29390 29367 29392 29391 29403 29400 29393 29394
29371 29375 29367 29370 29366 29372 29360 29371 29365 29399 29395 29401 29347 29395 29398
29369 29381 29372 29371 29367 29378 29406 29387 29360 29388 29392 29386 29394 29392 29390
29380 29374 29374 29368 29348 29356 29375 29360 29374 29388 29397 29389 29363 29397 29393
29352 29378 29374 29363 29367 29371 29372 29388 29373 29388 29386 29389 29388 29397 29390
29370 29380 29379 29337 29348 29361 29377 29346 29371 29390 29388 29389 29386 29400 29391
29356 29361 29342 29372 29363 29364 29355 29371 29364 29385 29384 29398 29345 29395 29390
29366 29368 29351 29362 29348 29366 29364 29371 29371 29389 29387 29397 29362 29400 29398
29370 29371 29376 29369 29363 29368 29354 29368 29371 29388 29387 29400 29355 29398 29396
29338 29375 29372 29370 29365 29341 29365 29351 29385 29390 29389 29389 29384 29395 29398
29368 29370 29376 29369 29356 29365 29353 29390 29377 29390 29389 29398 29382 29398 29398
29378 29377 29367 29368 29358 29346 29374 29345 29387 29388 29389 29398 29383 29398 29398
29364 29382 29364 29366 29368 29365 29348 29368 29369 29388 29387 29388 29382 29398 29399
29377 29361 29374 29348 29352 29364 29355 29349 29394 29402 29389 29389 29384 29394 29393
29374 29379 29347 29371 29335 29367 29371 29374 29374 29389 29388 29398 29365 29397 29388
29368 29377 29373 29365 29369 29364 29368 29353 29387 29385 29389 29386 29332 29402 29393
29320 29359 29377 29343 29364 29375 29357 29390 29360 29389 29391 29397 29383 29403 29398
29373 29377 29361 29371 29359 29378 29365 29370 29364 29388 29387 29398 29382 29395 29398
29368 29368 29374 29369 29362 29364 29355 29390 29352 29388 29386 29389 29382 29398 29394
29366 29371 29372 29370 29348 29369 29357 29349 29368 29389 29388 29398 29340 29389 29390
29373 29369 29379 29376 29347 29375 29356 29369 29364 29388 29387 29402 29383 29393 29398

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 29333 bytes 100%
1,000 29327 bytes -6 bytes 100%
10,000 29322 bytes -5 bytes 100%
100,000 29320 bytes -2 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
29452 bytes +132 bytes (+0.45%) +18 bytes
29448 bytes +128 bytes (+0.44%) +14 bytes
29488 bytes +168 bytes (+0.57%) +54 bytes
29465 bytes +145 bytes (+0.49%) +31 bytes
29434 bytes +114 bytes (+0.39%)
29478 bytes +158 bytes (+0.54%) +44 bytes
29461 bytes +141 bytes (+0.48%) +27 bytes
29483 bytes +163 bytes (+0.56%) +49 bytes
29523 bytes +203 bytes (+0.69%) +89 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 23263 bytes -6057 bytes (-20.66%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 26170 bytes -3150 bytes (-10.74%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 27084 bytes -2236 bytes (-7.63%)
Brotli (Wikipedia) brotli brotli -q 11 27227 bytes -2093 bytes (-7.14%)
LZMA2 (Wikipedia) xz xz -9 28124 bytes -1196 bytes (-4.08%)
ZSTD (Wikipedia) zstd zstd -19 28902 bytes -418 bytes (-1.43%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 29059 bytes -261 bytes (-0.89%)

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