Choose a version:
24% The original file has 1031730 bytes (1,007.5k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 248892 bytes (243.1k, 24%).

After GZIP compression these minified files vary in size:
Boot
  84874 bytes (82.9k)
CDN, direct link
Baidu
  70582 bytes (68.9k)
CDN, direct link
cdnjs
  70562 bytes (68.9k)
CDN, direct link
gzip -6 (default)
  69631 bytes (68.0k)
local copy
cdnhttps
  69544 bytes (67.9k)
CDN, direct link
gzip -9
  69286 bytes (67.7k)
local copy
7zip -mx=9 -tgzip
  66832 bytes (65.3k)
local copy
pigz -11 -n
  66633 bytes (65.1k)
local copy
libdeflate -12
  66632 bytes (65.1k)
local copy
kzip -s0 -rn -b1
  66613 bytes (65.1k)
local copy
Zopfli
  66526 bytes (65.0k)
local copy
Zopfli (defluff)
  66525 bytes (65.0k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/ember/ember-1.2.1.min.js

You will automatically get the smallest Ember 1.2.1 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 3018 bytes by using my Ember 1.2.1 Zopfli version instead of the best available CDN (4.54% smaller than cdnhttps, 66526 vs. 69544 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 --i1000000 --mb8 --mls4096 --bsr23 --lazy --ohh

(found July 23, 2016)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 4096  --mls4096
block splitting recursion 23  --bsr23
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 (66525 bytes).

Verify file integrity

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

MD5:
curl --silent --compressed http://builds.emberjs.com/tags/v1.2.1/ember.min.js --location | md5sum
0bc70ff0baf60d52cc037aef69354da1  -
curl --silent --compressed http://minime.stephan-brumme.com/files/ember/ember-1.2.1.min.zopfli.js.gz | md5sum
0bc70ff0baf60d52cc037aef69354da1  -

SHA1:
curl --silent --compressed http://builds.emberjs.com/tags/v1.2.1/ember.min.js --location | sha1sum
ba99292c8972055b9bcc93c3d8ea8c4c9cb6fa05  -
curl --silent --compressed http://minime.stephan-brumme.com/files/ember/ember-1.2.1.min.zopfli.js.gz | sha1sum
ba99292c8972055b9bcc93c3d8ea8c4c9cb6fa05  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 84874 bytes 0bc70ff0baf60d52cc037aef69354da1 March 19, 2015 @ 17:49
cdnjs 70562 bytes 0bc70ff0baf60d52cc037aef69354da1 January 14, 2014 @ 20:15
cdnhttps 69544 bytes 0bc70ff0baf60d52cc037aef69354da1 December 24, 2015 @ 07:33

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
Baidu 70582 bytes 203435b3cfab0cf10279ffc523f3c9d2 only whitespaces differ June 5, 2014 @ 10:05

Note: only the MD5 hashes are shown to keep things simple.

Other Versions

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

2.13.3, 2.13.2, 2.13.1, 2.13.0,
2.12.2, 2.12.1, 2.12.0,
2.11.3, 2.11.2, 2.11.1, 2.11.0,
2.10.2, 2.10.1, 2.10.0,
2.9.1, 2.9.0,
2.8.3, 2.8.2, 2.8.1, 2.8.0,
2.7.3, 2.7.2, 2.7.1, 2.7.0,
2.6.2, 2.6.1, 2.6.0,
2.5.1, 2.5.0,
2.4.6, 2.4.5, 2.4.4, 2.4.3, 2.4.2, 2.4.1, 2.4.0,
2.3.1, 2.3.0,
2.2.2, 2.2.1, 2.2.0,
2.1.2, 2.1.1, 2.1.0,
2.0.3, 2.0.2, 2.0.1, 2.0.0,
1.13.13, 1.13.12, 1.13.11, 1.13.10, 1.13.9, 1.13.8, 1.13.7, 1.13.6, 1.13.5, 1.13.4, 1.13.3, 1.13.2, 1.13.1, 1.13.0,
1.12.2, 1.12.1, 1.12.0,
1.11.4, 1.11.3, 1.11.2, 1.11.1, 1.11.0,
1.10.1, 1.10.0,
1.9.1, 1.9.0,
1.8.1, 1.8.0,
1.7.1, 1.7.0,
1.6.1, 1.6.0,
1.5.1, 1.5.0,
1.4.0,
1.3.2, 1.3.1, 1.3.0,
1.2.2, 1.2.1, 1.2.0,
1.0.1, 1.0.0

The project site contains an overview how well these versions were compressed.
Other interesting projects are AngularJS, BackboneJS, Bootstrap, D3, Dojo, jQuery, Knockout, lodash, React, Socket.IO, ThreeJS, UnderscoreJS and Vue.

Changelog

Best Zopfli parameters so far:
Size Improvement Parameters Found
66526 bytes -3 bytes zopfli --i1000000 --mls4096 --bsr23 --lazy --ohh July 23, 2016 @ 23:41
66529 bytes -1 byte zopfli --i100000 --mls4096 --bsr23 --lazy --ohh July 19, 2016 @ 19:10
66530 bytes -1 byte zopfli --i100000 --mls2 --bsr19 --lazy --ohh November 22, 2015 @ 14:00
66531 bytes -1 byte zopfli --i1000000 --mls8 --bsr17 --lazy --ohh November 21, 2015 @ 21:28
66532 bytes -4 bytes zopfli --i10000 --mls8 --bsr17 --lazy --ohh October 2, 2015 @ 17:35
66536 bytes -1 byte zopfli --i1000 --mls8 --bsr17 --lazy --ohh October 2, 2015 @ 16:23
66537 bytes -1 byte zopfli --i1000 --mls2 --bsr19 --lazy --ohh October 2, 2015 @ 16:22
66538 bytes -9 bytes zopfli --i1000 --mls2 --bsr18 --lazy --ohh October 2, 2015 @ 16:21
66547 bytes -1 byte zopfli --i1000 --mls8 --bsr2 --lazy --ohh October 2, 2015 @ 16:16
66548 bytes -2 bytes zopfli --i1000 --mls256 --bsr17 --lazy --ohh October 2, 2015 @ 16:12
66550 bytes -3 bytes zopfli --i1000 --mls64 --bsr18 --lazy --ohh October 2, 2015 @ 16:07
66553 bytes zopfli --i100 --mls64 --bsr18 --lazy --ohh September 30, 2015 @ 10:58

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

Most recent activity on March 27, 2017 @ 17:44.

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
66539 66539 66539 66539 66538 66536 66536 66536 66539 66537 66537 66536 66539 66539 66544
66540 66538 66538 66539 66533 66538 66534 66532 66534 66534 66535 66533 66537 66536 66543
66538 66538 66539 66534 66534 66533 66540 66535 66533 66534 66534 66534 66540 66537 66539
66542 66537 66538 66534 66538 66539 66541 66533 66533 66533 66534 66534 66538 66545 66537
66537 66538 66536 66535 66535 66539 66538 66535 66533 66533 66534 66534 66540 66549 66540
66537 66538 66534 66534 66535 66536 66542 66533 66534 66534 66534 66534 66535 66540 66546
66539 66539 66533 66533 66540 66538 66541 66533 66533 66534 66533 66534 66537 66547 66537
66536 66538 66536 66533 66537 66533 66539 66536 66533 66533 66534 66531 66537 66537 66541
66536 66537 66539 66533 66534 66538 66541 66538 66533 66534 66533 66529 66537 66545 66537
66536 66537 66538 66534 66535 66537 66541 66537 66533 66534 66534 66532 66540 66548 66537
66537 66536 66538 66535 66534 66540 66541 66535 66532 66534 66534 66534 66535 66541 66537
66536 66537 66537 66535 66534 66539 66541 66533 66531 66534 66534 66533 66536 66548 66540
66536 66536 66536 66533 66535 66537 66541 66537 66533 66534 66534 66535 66537 66545 66538
66538 66537 66531 66533 66534 66535 66541 66532 66533 66534 66532 66533 66537 66546 66538
66531 66537 66533 66533 66534 66535 66535 66533 66534 66534 66533 66531 66538 66545 66537
66530 66538 66539 66534 66538 66538 66540 66535 66531 66533 66534 66533 66536 66545 66535
66531 66537 66534 66535 66534 66539 66540 66534 66533 66534 66534 66534 66538 66545 66537
66537 66539 66534 66535 66534 66539 66540 66533 66532 66534 66534 66532 66537 66544 66541
66537 66537 66534 66535 66534 66539 66541 66533 66533 66534 66534 66534 66536 66545 66539
66537 66537 66538 66542 66534 66538 66541 66533 66535 66534 66533 66526 66537 66545 66540
66536 66535 66534 66533 66534 66537 66540 66538 66533 66534 66533 66534 66538 66545 66536
66535 66538 66536 66533 66537 66538 66540 66532 66533 66534 66534 66533 66536 66545 66537
66532 66537 66538 66535 66541 66538 66540 66538 66530 66534 66534 66534 66536 66545 66546

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 66553 bytes 100%
1,000 66536 bytes -17 bytes 100%
10,000 66531 bytes -5 bytes 100%
100,000 66529 bytes -2 bytes 3.77%
1,000,000 66526 bytes -3 bytes 1.16%
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
66655 bytes +129 bytes (+0.19%) +42 bytes
66613 bytes +87 bytes (+0.13%)
66656 bytes +130 bytes (+0.20%) +43 bytes
66668 bytes +142 bytes (+0.21%) +55 bytes
66658 bytes +132 bytes (+0.20%) +45 bytes
66707 bytes +181 bytes (+0.27%) +94 bytes
66727 bytes +201 bytes (+0.30%) +114 bytes
66772 bytes +246 bytes (+0.37%) +159 bytes
66782 bytes +256 bytes (+0.38%) +169 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 48344 bytes -18182 bytes (-27.33%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 51208 bytes -15318 bytes (-23.03%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 55082 bytes -11444 bytes (-17.20%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 58225 bytes -8301 bytes (-12.48%)
Brotli (Wikipedia) brotli brotli -q 11 59346 bytes -7180 bytes (-10.79%)
LZMA2 (Wikipedia) xz xz -9 61088 bytes -5438 bytes (-8.17%)
ZSTD (Wikipedia) zstd zstd -19 62682 bytes -3844 bytes (-5.78%)

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 2017.
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