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
  29470 bytes (28.8k)
local copy
kzip -s0 -rn -b4
  29435 bytes (28.7k)
local copy
zultra
  29423 bytes (28.7k)
local copy
pigz -11 -n
  29411 bytes (28.7k)
local copy
Zopfli
  29314 bytes (28.6k)
local copy
Zopfli (defluff)
  29313 bytes (28.6k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/dojo/dojo-1.5.5.min.js (or via HTTPS)

You will automatically get the smallest Dojo 1.5.5 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 --mls4 --bsr30 --lazy --ohh

(found February 27, 2020)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 4  --mls4
block splitting recursion 30  --bsr30
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 (29313 bytes).

Verify file integrity

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

MD5:
curl --silent --compressed https://download.dojotoolkit.org/release-1.5.5/dojo.js --location | md5sum
c3391a754e50f8f5ae25e61d43542621  -
curl --silent --compressed https://minime.stephan-brumme.com/files/dojo/dojo-1.5.5.min.zopfli.js.gz | md5sum
c3391a754e50f8f5ae25e61d43542621  -

SHA1:
curl --silent --compressed https://download.dojotoolkit.org/release-1.5.5/dojo.js --location | sha1sum
ed34cb5b6a5f5708984a22a8bbc0049ee20f4c20  -
curl --silent --compressed https://minime.stephan-brumme.com/files/dojo/dojo-1.5.5.min.zopfli.js.gz | sha1sum
ed34cb5b6a5f5708984a22a8bbc0049ee20f4c20  -

Other Versions

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

1.16.3, 1.16.2, 1.16.1, 1.16.0,
1.15.4, 1.15.3, 1.15.2, 1.15.1, 1.15.0,
1.14.7, 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
29314 bytes -1 byte zopfli --i1000000 --mls4 --bsr30 --lazy --ohh February 27, 2020 @ 22:44
29315 bytes -3 bytes zopfli --i100000 --mls4 --bsr30 --lazy --ohh January 28, 2020 @ 18:13
29318 bytes -5 bytes zopfli --i10000 --mls4 --bsr30 --lazy --ohh January 28, 2020 @ 17:41
29323 bytes -1 byte zopfli --i1000 --mls4 --bsr30 --lazy --ohh January 28, 2020 @ 16:44
29324 bytes zopfli --i100 --mls4 --bsr30 --lazy --ohh January 28, 2020 @ 13:36

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

Most recent activity on July 20, 2020 @ 12:51.

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
29368 29363 29370 29375 29393 29385 29387 29374 29404 29402 29402 29389 29392 29405 29393
29379 29388 29379 29369 29370 29388 29353 29389 29353 29393 29387 29395 29341 29396 29397
29346 29381 29362 29375 29370 29372 29353 29393 29360 29392 29388 29387 29344 29394 29394
29371 29374 29366 29362 29347 29372 29361 29373 29361 29399 29390 29399 29400 29394 29397
29374 29382 29371 29370 29369 29373 29394 29392 29349 29400 29368 29386 29370 29392 29395
29379 29374 29368 29367 29344 29363 29377 29353 29388 29399 29396 29397 29349 29396 29393
29351 29358 29375 29364 29363 29369 29372 29345 29360 29386 29385 29388 29381 29401 29390
29375 29381 29347 29338 29349 29362 29365 29341 29360 29389 29386 29388 29381 29399 29397
29353 29360 29376 29374 29363 29366 29366 29345 29364 29385 29386 29397 29348 29395 29389
29365 29377 29358 29345 29348 29365 29368 29367 29371 29386 29384 29395 29363 29400 29397
29369 29367 29370 29369 29366 29370 29353 29369 29365 29389 29388 29397 29387 29403 29395
29346 29374 29375 29367 29367 29338 29368 29349 29372 29388 29388 29388 29381 29394 29397
29367 29370 29375 29369 29370 29347 29356 29395 29377 29390 29387 29388 29381 29400 29397
29369 29367 29373 29373 29355 29345 29362 29346 29362 29386 29389 29388 29382 29392 29397
29373 29381 29375 29349 29365 29362 29352 29367 29338 29398 29387 29387 29387 29397 29396
29379 29360 29372 29345 29357 29363 29354 29347 29392 29398 29388 29388 29387 29396 29397
29369 29377 29373 29369 29334 29368 29370 29373 29361 29388 29385 29386 29364 29397 29397
29365 29369 29376 29362 29354 29370 29363 29349 29387 29399 29386 29386 29337 29398 29394
29322 29358 29377 29331 29365 29360 29348 29395 29345 29398 29386 29388 29382 29399 29396
29372 29377 29350 29364 29351 29373 29366 29365 29367 29388 29387 29387 29382 29401 29389
29367 29366 29351 29364 29361 29362 29353 29394 29351 29385 29395 29388 29393 29387 29389
29366 29314 29379 29368 29351 29387 29359 29348 29391 29387 29387 29387 29395 29388 29388
29369 29365 29374 29369 29348 29374 29350 29370 29349 29384 29386 29387 29381 29396 29396

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 29324 bytes 100%
1,000 29323 bytes -1 byte 100%
10,000 29318 bytes -5 bytes 100%
100,000 29315 bytes -3 bytes 0.58%
1,000,000 29314 bytes -1 byte 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 +153 bytes (+0.52%) +32 bytes
29467 bytes +153 bytes (+0.52%) +32 bytes
29487 bytes +173 bytes (+0.59%) +52 bytes
29467 bytes +153 bytes (+0.52%) +32 bytes
29435 bytes +121 bytes (+0.41%)
29480 bytes +166 bytes (+0.57%) +45 bytes
29465 bytes +151 bytes (+0.52%) +30 bytes
29485 bytes +171 bytes (+0.58%) +50 bytes
29529 bytes +215 bytes (+0.73%) +94 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 23262 bytes -6052 bytes (-20.65%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 26170 bytes -3144 bytes (-10.73%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 27083 bytes -2231 bytes (-7.61%)
Brotli (Wikipedia) brotli brotli -q 11 27221 bytes -2093 bytes (-7.14%)
LZMA2 (Wikipedia) xz xz -9 28116 bytes -1198 bytes (-4.09%)
Zstandard (Wikipedia) zstd zstd -19 28774 bytes -540 bytes (-1.84%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 29063 bytes -251 bytes (-0.86%)

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.