Choose a version:
27% The original file has 1724405 bytes (1,684.0k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 460906 bytes (450.1k, 27%).

After GZIP compression these minified files vary in size:
Boot
  145240 bytes (141.8k)
CDN
cdnjs
  119092 bytes (116.3k)
CDN
gzip -6 (default)
  117261 bytes (114.5k)
local copy
gzip -9
  116850 bytes (114.1k)
local copy
cdnhttps
  116728 bytes (114.0k)
CDN
7zip -mx=9 -tgzip
  113023 bytes (110.4k)
local copy
libdeflate -12
  112892 bytes (110.2k)
local copy
pigz -11 -n
  112800 bytes (110.2k)
local copy
kzip -s0 -rn -b5
  112665 bytes (110.0k)
local copy
Zopfli
  112585 bytes (109.9k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/ember/ember-2.5.1.min.js

You will automatically get the smallest Ember 2.5.1 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 4143 bytes by using my Ember 2.5.1 Zopfli version instead of the best available CDN (3.68% smaller than cdnhttps, 112585 vs. 116728 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 --mls32 --bsr25 --lazy --ohh

(found April 23, 2016)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 32  --mls32
block splitting recursion 25  --bsr25
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 http://builds.emberjs.com/tags/v2.5.1/ember.min.js --location | md5sum
3ab26e3d1443f782314d3b0c8dfe22ce  -
curl --silent --compressed http://minime.stephan-brumme.com/files/ember/ember-2.5.1.min.zopfli.js.gz | md5sum
3ab26e3d1443f782314d3b0c8dfe22ce  -

SHA1:
curl --silent --compressed http://builds.emberjs.com/tags/v2.5.1/ember.min.js --location | sha1sum
d8d1d963fb8c27433aa502bc2f02d5cd19fbce2f  -
curl --silent --compressed http://minime.stephan-brumme.com/files/ember/ember-2.5.1.min.zopfli.js.gz | sha1sum
d8d1d963fb8c27433aa502bc2f02d5cd19fbce2f  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 145240 bytes 3ab26e3d1443f782314d3b0c8dfe22ce May 3, 2016 @ 11:52
cdnjs 119092 bytes 3ab26e3d1443f782314d3b0c8dfe22ce April 22, 2016 @ 00:16
cdnhttps 116728 bytes 3ab26e3d1443f782314d3b0c8dfe22ce November 22, 2016 @ 16:33

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

Other Versions

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

3.0.0,
2.18.2, 2.18.1, 2.18.0,
2.17.2, 2.17.1, 2.17.0,
2.16.2, 2.16.1, 2.16.0,
2.15.3, 2.15.2, 2.15.1, 2.15.0,
2.14.1, 2.14.0,
2.13.4, 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
112585 bytes -2 bytes zopfli --i1000000 --mls32 --bsr25 --lazy --ohh April 23, 2016 @ 18:28
112587 bytes -1 byte zopfli --i100000 --mls32 --bsr25 --lazy --ohh April 22, 2016 @ 18:37
112588 bytes -6 bytes zopfli --i100000 --mls32 --bsr11 --lazy --ohh April 22, 2016 @ 13:30
112594 bytes -9 bytes zopfli --i10000 --mls32 --bsr11 --lazy --ohh April 22, 2016 @ 10:25
112603 bytes -10 bytes zopfli --i10000 --mls8192 --bsr23 --lazy --ohh April 22, 2016 @ 09:31
112613 bytes -21 bytes zopfli --i1000 --mls8192 --bsr23 --lazy --ohh April 22, 2016 @ 09:17
112634 bytes zopfli --i100 --mls8192 --bsr23 --lazy --ohh April 22, 2016 @ 09:07

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

Most recent activity on November 22, 2016 @ 16:33.

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
112703 112699 112724 112719 112719 112703 112705 112715 112757 112721 112719 112720 112768 112722 112774
112622 112621 112671 112629 112597 112597 112716 112612 112618 112650 112664 112720 112768 112631 112711
112600 112596 112608 112607 112612 112620 112627 112636 112605 112640 112641 112715 112611 112634 112774
112712 112715 112714 112712 112711 112711 112712 112712 112712 112713 112711 112711 112621 112621 112720
112715 112710 112709 112709 112594 112713 112712 112707 112712 112712 112713 112711 112717 112629 112710
112713 112715 112714 112709 112602 112711 112710 112707 112711 112713 112712 112708 112618 112715 112716
112712 112711 112711 112709 112594 112711 112710 112713 112713 112713 112713 112712 112641 112711 112718
112711 112710 112718 112709 112588 112711 112712 112707 112711 112713 112713 112711 112612 112706 112716
112713 112712 112710 112713 112713 112711 112709 112711 112712 112713 112713 112710 112618 112715 112711
112714 112712 112713 112709 112587 112711 112711 112715 112713 112719 112713 112711 112717 112714 112715
112712 112712 112713 112710 112615 112594 112712 112707 112712 112713 112718 112712 112617 112715 112718
112712 112711 112713 112712 112598 112711 112710 112707 112712 112712 112713 112713 112611 112714 112714
112714 112713 112712 112717 112598 112712 112710 112712 112711 112713 112717 112711 112720 112711 112710
112713 112712 112714 112709 112601 112712 112712 112707 112711 112713 112712 112712 112617 112715 112717
112712 112712 112713 112711 112595 112598 112712 112713 112712 112715 112717 112711 112614 112710 112716
112713 112714 112713 112709 112713 112711 112711 112713 112713 112712 112713 112713 112717 112715 112718
112713 112712 112714 112709 112609 112600 112712 112713 112713 112712 112714 112711 112610 112715 112716
112712 112710 112713 112709 112587 112711 112710 112707 112713 112713 112718 112713 112617 112712 112716
112712 112711 112713 112709 112601 112597 112712 112707 112712 112713 112713 112712 112621 112714 112710
112712 112711 112714 112709 112588 112712 112711 112707 112713 112713 112713 112711 112596 112715 112710
112712 112711 112714 112709 112585 112594 112711 112710 112712 112713 112713 112713 112605 112715 112711
112711 112710 112713 112712 112599 112600 112710 112712 112712 112714 112713 112713 112599 112713 112716
112713 112711 112713 112709 112600 112713 112710 112713 112713 112713 112713 112712 112613 112713 112718

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 112634 bytes 100%
1,000 112603 bytes -31 bytes 100%
10,000 112592 bytes -11 bytes 100%
100,000 112587 bytes -5 bytes 1.74%
1,000,000 112585 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
112791 bytes +206 bytes (+0.18%) +126 bytes
112734 bytes +149 bytes (+0.13%) +69 bytes
112785 bytes +200 bytes (+0.18%) +120 bytes
112748 bytes +163 bytes (+0.14%) +83 bytes
112754 bytes +169 bytes (+0.15%) +89 bytes
112665 bytes +80 bytes (+0.07%)
112709 bytes +124 bytes (+0.11%) +44 bytes
112769 bytes +184 bytes (+0.16%) +104 bytes
112805 bytes +220 bytes (+0.20%) +140 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 76639 bytes -35946 bytes (-31.93%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 82105 bytes -30480 bytes (-27.07%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 88583 bytes -24002 bytes (-21.32%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 93392 bytes -19193 bytes (-17.05%)
Brotli (Wikipedia) brotli brotli -q 11 97707 bytes -14878 bytes (-13.21%)
LZMA2 (Wikipedia) xz xz -9 99836 bytes -12749 bytes (-11.32%)
ZSTD (Wikipedia) zstd zstd -19 102659 bytes -9926 bytes (-8.82%)

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