Choose a version:
26% The original file has 621713 bytes (607.1k) 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
  64013 bytes (62.5k)
CDN
cdnhttps
  55589 bytes (54.3k)
CDN
cdnjs
  55472 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
  52555 bytes (51.3k)
local copy
pigz -11 -n
  52503 bytes (51.3k)
local copy
kzip -s0 -rn -b1
  52497 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-1.9.7.min.js

You will automatically get the smallest Dojo 1.9.7 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 3150 bytes by using my Dojo 1.9.7 Zopfli version instead of the best available CDN (6.02% smaller than cdnjs, 52322 vs. 55472 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 --bsr15 --lazy --ohh

(found September 28, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 8  --mls8
block splitting recursion 15  --bsr15
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-1.9.7/dojo.js --location | md5sum
4c904708e42ec4202f67d60e2a9e7934  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.9.7.min.zopfli.js.gz | md5sum
4c904708e42ec4202f67d60e2a9e7934  -

SHA1:
curl --silent --compressed http://download.dojotoolkit.org/release-1.9.7/dojo.js --location | sha1sum
669dd0e027780b8ef9e6dbff6eb584bef83967aa  -
curl --silent --compressed http://minime.stephan-brumme.com/files/dojo/dojo-1.9.7.min.zopfli.js.gz | sha1sum
669dd0e027780b8ef9e6dbff6eb584bef83967aa  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 64013 bytes 4c904708e42ec4202f67d60e2a9e7934 March 19, 2015 @ 15:45
cdnjs 55472 bytes 4c904708e42ec4202f67d60e2a9e7934 February 8, 2015 @ 14:45

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
cdnhttps 55589 bytes 498bbe4108b109fd95fe88562c9e7d75 < /*
< 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 -7 bytes zopfli --i100000 --mls8 --bsr15 --lazy --ohh September 28, 2015 @ 06:29
52329 bytes -8 bytes zopfli --i10000 --mls8 --bsr15 --lazy --ohh September 27, 2015 @ 17:15
52337 bytes -6 bytes zopfli --i1000 --mls8 --bsr15 --lazy --ohh September 18, 2015 @ 23:09
52343 bytes -15 bytes zopfli --i1000 --mls8 --bsr16 --lazy --ohh September 18, 2015 @ 22:32
52358 bytes -1 byte zopfli --i1000 --mls8 --bsr6 --lazy --ohh September 18, 2015 @ 22:13
52359 bytes zopfli --i100 --mls8 --bsr15 --lazy --ohh September 18, 2015 @ 15:56

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
52402 52400 52398 52401 52402 52402 52401 52401 52400 52417 52397 52421 52426 52419 52401
52364 52350 52340 52393 52410 52403 52414 52407 52403 52401 52405 52416 52416 52403 52401
52353 52346 52349 52395 52395 52402 52398 52397 52401 52399 52408 52420 52413 52417 52403
52395 52394 52329 52401 52395 52401 52402 52413 52402 52402 52411 52417 52411 52410 52401
52340 52337 52322 52396 52395 52395 52398 52394 52399 52412 52409 52418 52407 52398 52406
52342 52338 52353 52394 52395 52395 52399 52395 52404 52409 52402 52417 52414 52408 52404
52358 52359 52353 52394 52398 52395 52395 52397 52403 52402 52407 52419 52413 52416 52404
52341 52341 52354 52396 52396 52395 52398 52398 52403 52399 52412 52418 52418 52397 52404
52344 52338 52339 52393 52395 52395 52395 52399 52400 52398 52411 52417 52413 52395 52413
52343 52338 52357 52394 52395 52395 52395 52394 52400 52396 52396 52417 52414 52406 52402
52340 52341 52415 52395 52397 52394 52396 52396 52403 52394 52409 52415 52413 52408 52403
52341 52338 52322 52403 52395 52395 52395 52406 52399 52399 52410 52416 52417 52401 52403
52335 52342 52333 52394 52394 52396 52400 52401 52399 52400 52400 52417 52415 52401 52402
52344 52339 52415 52397 52395 52397 52398 52395 52398 52409 52410 52416 52418 52397 52404
52344 52346 52342 52395 52396 52395 52398 52398 52398 52393 52403 52418 52416 52396 52404
52341 52395 52395 52395 52395 52395 52402 52394 52400 52393 52409 52417 52416 52401 52403
52340 52340 52359 52395 52397 52396 52395 52399 52403 52393 52411 52416 52417 52418 52403
52341 52340 52355 52395 52393 52395 52397 52395 52398 52409 52403 52417 52414 52401 52403
52348 52341 52340 52395 52396 52395 52399 52398 52402 52409 52395 52409 52417 52412 52406
52341 52340 52355 52395 52400 52396 52399 52395 52400 52399 52412 52416 52413 52412 52403
52347 52348 52351 52394 52396 52395 52399 52407 52402 52398 52406 52417 52414 52399 52403
52338 52342 52348 52394 52397 52395 52399 52397 52402 52410 52410 52416 52417 52401 52404
52341 52338 52339 52394 52395 52395 52395 52397 52403 52409 52410 52417 52416 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 52350 bytes 100%
1,000 52337 bytes -13 bytes 100%
10,000 52329 bytes -8 bytes 100%
100,000 52322 bytes -7 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%) +62 bytes
52497 bytes +175 bytes (+0.33%)
52515 bytes +193 bytes (+0.37%) +18 bytes
52561 bytes +239 bytes (+0.46%) +64 bytes
52594 bytes +272 bytes (+0.52%) +97 bytes
52610 bytes +288 bytes (+0.55%) +113 bytes
52618 bytes +296 bytes (+0.57%) +121 bytes
52647 bytes +325 bytes (+0.62%) +150 bytes
52668 bytes +346 bytes (+0.66%) +171 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 38447 bytes -13875 bytes (-26.52%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 45530 bytes -6792 bytes (-12.98%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 46850 bytes -5472 bytes (-10.46%)
Brotli (Wikipedia) brotli brotli -q 11 47950 bytes -4372 bytes (-8.36%)
LZMA2 (Wikipedia) xz xz -9 49112 bytes -3210 bytes (-6.14%)
ZSTD (Wikipedia) zstd zstd -19 50593 bytes -1729 bytes (-3.30%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 50624 bytes -1698 bytes (-3.25%)

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