Choose a version:
26% The original file has 606576 bytes (592.4k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 158637 bytes (154.9k, 26%).

After GZIP compression these minified files vary in size:
Boot
  62910 bytes (61.4k)
CDN
cdnhttps
  54620 bytes (53.3k)
CDN
cdnjs
  54543 bytes (53.3k)
CDN
gzip -6 (default)
  54296 bytes (53.0k)
local copy
gzip -9
  54228 bytes (53.0k)
local copy
7zip -mx=9 -tgzip
  51665 bytes (50.5k)
local copy
libdeflate -12
  51622 bytes (50.4k)
local copy
kzip -s0 -rn -b1
  51584 bytes (50.4k)
local copy
pigz -11 -n
  51564 bytes (50.4k)
local copy
Zopfli
  51409 bytes (50.2k)
local copy
Zopfli (defluff)
  51407 bytes (50.2k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/dojo/dojo-1.8.6.min.js (or via HTTPS)

You will automatically get the smallest Dojo 1.8.6 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 3134 bytes by using my Dojo 1.8.6 Zopfli version instead of the best available CDN (6.10% smaller than cdnjs, 51409 vs. 54543 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 --bsr4 --lazy --ohh

(found October 21, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 2  --mls2
block splitting recursion 4  --bsr4
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 (51407 bytes).

Verify file integrity

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

MD5:
curl --silent --compressed https://download.dojotoolkit.org/release-1.8.6/dojo.js --location | md5sum
fca7de428f976d71cb0342e558f00024  -
curl --silent --compressed https://minime.stephan-brumme.com/files/dojo/dojo-1.8.6.min.zopfli.js.gz | md5sum
fca7de428f976d71cb0342e558f00024  -

SHA1:
curl --silent --compressed https://download.dojotoolkit.org/release-1.8.6/dojo.js --location | sha1sum
c5a8bc66407a76b4f95958d448025ae0657e836b  -
curl --silent --compressed https://minime.stephan-brumme.com/files/dojo/dojo-1.8.6.min.zopfli.js.gz | sha1sum
c5a8bc66407a76b4f95958d448025ae0657e836b  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 62910 bytes fca7de428f976d71cb0342e558f00024 March 19, 2015 @ 15:40
cdnjs 54543 bytes fca7de428f976d71cb0342e558f00024 February 8, 2015 @ 14:45

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
cdnhttps 54620 bytes 5a72b93a23fdfa100cdc1ca5d1a19034 < /*
< 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:

1.14.2, 1.14.1, 1.14.0,
1.13.3, 1.13.2, 1.13.1, 1.13.0,
1.12.4, 1.12.3, 1.12.2, 1.12.1,
1.11.6, 1.11.5, 1.11.4, 1.11.3, 1.11.2, 1.11.1, 1.11.0,
1.10.10, 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,
1.8.14, 1.8.13, 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,
1.7.12, 1.7.11, 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
51409 bytes -3 bytes zopfli --i100000 --mls2 --bsr4 --lazy --ohh October 21, 2015 @ 10:57
51412 bytes -5 bytes zopfli --i10000 --mls2 --bsr4 --lazy --ohh October 21, 2015 @ 10:21
51417 bytes -7 bytes zopfli --i1000 --mls2 --bsr4 --lazy --ohh September 23, 2015 @ 01:39
51424 bytes zopfli --i100 --mls2 --bsr4 --lazy --ohh September 22, 2015 @ 12:08

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 @ 14:38.

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
51481 51480 51481 51481 51477 51482 51478 51478 51480 51479 51473 51507 51496 51511 51498
51409 51412 51477 51478 51475 51477 51489 51477 51489 51481 51473 51498 51488 51481 51498
51437 51447 51477 51474 51477 51485 51475 51482 51482 51482 51494 51490 51488 51504 51488
51488 51451 51487 51471 51473 51477 51474 51476 51473 51474 51477 51498 51482 51485 51485
51433 51432 51473 51471 51473 51494 51481 51473 51473 51474 51489 51499 51490 51498 51497
51429 51433 51475 51473 51473 51474 51475 51481 51487 51483 51491 51486 51495 51495 51490
51435 51432 51492 51472 51474 51484 51474 51478 51473 51478 51475 51500 51489 51486 51495
51431 51434 51473 51471 51474 51473 51477 51478 51473 51484 51495 51499 51501 51495 51482
51429 51433 51472 51472 51472 51474 51478 51486 51473 51479 51495 51499 51502 51479 51472
51441 51435 51472 51485 51476 51476 51476 51478 51477 51475 51473 51472 51487 51487 51499
51432 51430 51473 51472 51472 51474 51475 51473 51479 51476 51474 51489 51500 51486 51498
51433 51435 51474 51471 51472 51473 51478 51477 51473 51479 51472 51492 51497 51492 51498
51439 51433 51472 51473 51472 51473 51477 51474 51478 51472 51473 51501 51502 51495 51498
51450 51432 51472 51473 51473 51473 51481 51480 51473 51476 51489 51476 51484 51486 51482
51432 51441 51473 51473 51474 51473 51481 51475 51472 51474 51492 51500 51503 51495 51482
51431 51437 51472 51473 51474 51474 51474 51481 51478 51475 51475 51485 51486 51503 51482
51429 51431 51477 51474 51473 51475 51474 51478 51476 51474 51473 51501 51483 51507 51490
51431 51431 51473 51473 51473 51474 51476 51472 51476 51474 51501 51484 51502 51502 51501
51429 51429 51472 51473 51474 51473 51490 51477 51473 51474 51490 51499 51502 51510 51498
51431 51433 51473 51472 51474 51473 51477 51476 51475 51476 51490 51489 51492 51494 51472
51429 51431 51473 51472 51475 51473 51476 51489 51475 51474 51474 51488 51502 51495 51488
51433 51429 51474 51473 51475 51473 51477 51475 51482 51474 51473 51499 51502 51496 51498
51433 51436 51471 51472 51479 51473 51475 51480 51477 51474 51472 51492 51498 51481 51498

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 51424 bytes 100%
1,000 51417 bytes -7 bytes 100%
10,000 51412 bytes -5 bytes 100%
100,000 51409 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
51640 bytes +231 bytes (+0.45%) +56 bytes
51584 bytes +175 bytes (+0.34%)
51597 bytes +188 bytes (+0.37%) +13 bytes
51641 bytes +232 bytes (+0.45%) +57 bytes
51659 bytes +250 bytes (+0.49%) +75 bytes
51680 bytes +271 bytes (+0.53%) +96 bytes
51722 bytes +313 bytes (+0.61%) +138 bytes
51710 bytes +301 bytes (+0.59%) +126 bytes
51720 bytes +311 bytes (+0.60%) +136 bytes

Non-DEFLATE Algorithms

Archivers based on completely different compression algorithms often produce superior results.
Unfortunately, browsers only support gzip compression at the moment.
However, support for Brotli is constantly growing - but your browser doesn't support it.
Algorithm Program Parameters Size Compared To Best Zopfli
ZPAQ (Wikipedia) zpaq zpaq -method 69 37780 bytes -13629 bytes (-26.51%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 44747 bytes -6662 bytes (-12.96%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 46135 bytes -5274 bytes (-10.26%)
Brotli (Wikipedia) brotli brotli -q 11 47217 bytes -4192 bytes (-8.15%)
LZMA2 (Wikipedia) xz xz -9 48248 bytes -3161 bytes (-6.15%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 49640 bytes -1769 bytes (-3.44%)
Zstandard (Wikipedia) zstd zstd -19 49734 bytes -1675 bytes (-3.26%)

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