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:
gzip -6 (default)
  30879 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
  29469 bytes (28.8k)
local copy
kzip -s0 -rn -b4
  29435 bytes (28.7k)
local copy
pigz -11 -n
  29411 bytes (28.7k)
local copy
Zopfli
  29320 bytes (28.6k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/dojo/dojo-1.5.6.min.js (or via HTTPS)

You will automatically get the smallest Dojo 1.5.6 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

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 --i1000000 --mb8 --mls2 --bsr22 --lazy --ohh

(found February 27, 2020)
Description Value Parameter
iterations 1000000  --i1000000
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

Verify file integrity

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

MD5:
curl --silent --compressed https://download.dojotoolkit.org/release-1.5.6/dojo.js --location | md5sum
762704308881db6e92ad1ab8034e47f6  -
curl --silent --compressed https://minime.stephan-brumme.com/files/dojo/dojo-1.5.6.min.zopfli.js.gz | md5sum
762704308881db6e92ad1ab8034e47f6  -

SHA1:
curl --silent --compressed https://download.dojotoolkit.org/release-1.5.6/dojo.js --location | sha1sum
53e6faef34b52b28e513b58de58992d0e1316cce  -
curl --silent --compressed https://minime.stephan-brumme.com/files/dojo/dojo-1.5.6.min.zopfli.js.gz | sha1sum
53e6faef34b52b28e513b58de58992d0e1316cce  -

Other Versions

Available Dojo versions at minime.stephan-brumme.com:

1.16.2, 1.16.1, 1.16.0,
1.15.3, 1.15.2, 1.15.1, 1.15.0,
1.14.6, 1.14.5, 1.14.4, 1.14.3, 1.14.2, 1.14.1, 1.14.0,
1.13.5, 1.13.4, 1.13.3, 1.13.2, 1.13.1, 1.13.0,
1.12.5, 1.12.4, 1.12.3, 1.12.2, 1.12.1,
1.11.8, 1.11.7, 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,
1.6.5, 1.6.4, 1.6.3, 1.6.2, 1.6.1, 1.6.0,
1.5.6, 1.5.5, 1.5.4, 1.5.3, 1.5.2, 1.5.1, 1.5.0,
1.4.8, 1.4.7, 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, 1.2.2

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 --i1000000 --mls2 --bsr22 --lazy --ohh February 27, 2020 @ 17:30
29322 bytes -2 bytes zopfli --i100000 --mls2 --bsr22 --lazy --ohh January 28, 2020 @ 21:07
29324 bytes -4 bytes zopfli --i10000 --mls2 --bsr22 --lazy --ohh January 28, 2020 @ 20:42
29328 bytes -5 bytes zopfli --i1000 --mls2 --bsr22 --lazy --ohh January 28, 2020 @ 14:52
29333 bytes zopfli --i100 --mls2 --bsr22 --lazy --ohh January 28, 2020 @ 13:17

If there are multiple parameter sets yielding the same compressed size, only the first one found is shown.

Most recent activity on February 27, 2020 @ 17:30.

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, 100,000 or 1,000,000.
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
29367 29364 29366 29376 29394 29385 29378 29375 29398 29402 29397 29384 29392 29404 29396
29379 29387 29377 29371 29365 29377 29350 29391 29355 29393 29387 29398 29341 29399 29397
29353 29379 29361 29378 29358 29367 29352 29396 29356 29398 29391 29397 29399 29392 29393
29372 29375 29367 29369 29365 29371 29359 29371 29363 29387 29392 29399 29348 29393 29397
29374 29336 29374 29372 29363 29373 29349 29393 29359 29390 29389 29387 29393 29392 29394
29379 29375 29370 29367 29344 29356 29374 29359 29361 29399 29396 29397 29387 29399 29398
29355 29357 29374 29365 29370 29369 29370 29387 29362 29390 29387 29387 29387 29401 29390
29374 29378 29348 29341 29347 29360 29376 29345 29360 29388 29387 29386 29337 29398 29390
29352 29359 29348 29373 29362 29364 29347 29370 29363 29386 29387 29395 29344 29402 29389
29365 29368 29369 29361 29347 29365 29377 29372 29370 29386 29385 29396 29364 29398 29398
29369 29372 29368 29370 29362 29368 29353 29370 29388 29387 29386 29398 29387 29397 29394
29346 29376 29370 29369 29364 29340 29364 29351 29376 29389 29389 29388 29381 29393 29397
29368 29370 29375 29367 29358 29364 29352 29389 29375 29389 29387 29397 29354 29395 29397
29368 29367 29377 29368 29356 29345 29373 29344 29362 29388 29389 29398 29381 29393 29397
29380 29379 29369 29365 29367 29367 29348 29367 29368 29387 29390 29397 29381 29401 29398
29389 29360 29375 29347 29351 29363 29357 29348 29393 29387 29387 29398 29387 29395 29395
29368 29376 29345 29370 29333 29378 29365 29373 29363 29387 29391 29397 29364 29396 29392
29364 29374 29372 29363 29368 29363 29367 29350 29385 29399 29388 29385 29387 29397 29397
29320 29356 29373 29340 29363 29372 29356 29389 29359 29389 29386 29396 29387 29398 29395
29377 29375 29350 29366 29358 29358 29365 29369 29366 29384 29382 29397 29382 29398 29389
29367 29368 29367 29372 29361 29363 29353 29396 29350 29385 29383 29397 29388 29397 29389
29376 29371 29368 29364 29345 29387 29351 29348 29367 29387 29388 29397 29396 29394 29398
29371 29368 29372 29368 29345 29373 29350 29368 29363 29384 29386 29397 29381 29392 29394

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 29328 bytes -5 bytes 100%
10,000 29324 bytes -4 bytes 100%
100,000 29322 bytes -2 bytes 0.58%
1,000,000 29320 bytes -2 bytes 0.29%
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
29467 bytes +147 bytes (+0.50%) +32 bytes
29467 bytes +147 bytes (+0.50%) +32 bytes
29488 bytes +168 bytes (+0.57%) +53 bytes
29470 bytes +150 bytes (+0.51%) +35 bytes
29435 bytes +115 bytes (+0.39%)
29482 bytes +162 bytes (+0.55%) +47 bytes
29464 bytes +144 bytes (+0.49%) +29 bytes
29486 bytes +166 bytes (+0.57%) +51 bytes
29526 bytes +206 bytes (+0.70%) +91 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 - for example, your browser actually supports it !
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 27086 bytes -2234 bytes (-7.62%)
Brotli (Wikipedia) brotli brotli -q 11 27232 bytes -2088 bytes (-7.12%)
LZMA2 (Wikipedia) xz xz -9 28120 bytes -1200 bytes (-4.09%)
Zstandard (Wikipedia) zstd zstd -19 28775 bytes -545 bytes (-1.86%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 29076 bytes -244 bytes (-0.83%)

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 2020.
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

All trademarks are property of their respective owners. You know, the boring legal stuff.