Choose a version:
30% The original file has 1620131 bytes (1,582.2k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 486857 bytes (475.4k, 30%).

After GZIP compression these minified files vary in size:
cdnjs
  123490 bytes (120.6k)
CDN
gzip -6 (default)
  121938 bytes (119.1k)
local copy
gzip -9
  121429 bytes (118.6k)
local copy
libdeflate -12
  117292 bytes (114.5k)
local copy
7zip -mx=9 -tgzip
  117271 bytes (114.5k)
local copy
pigz -11 -n
  117153 bytes (114.4k)
local copy
kzip -s0 -rn -b3
  117038 bytes (114.3k)
local copy
Zopfli
  116961 bytes (114.2k)
local copy
Zopfli (defluff)
  116958 bytes (114.2k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/ember/ember-2.18.1.min.js

You will automatically get the smallest Ember 2.18.1 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 6529 bytes by using my Ember 2.18.1 Zopfli version instead of the best available CDN (5.58% smaller than cdnjs, 116961 vs. 123490 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 --mls8192 --bsr7 --lazy --ohh

(found February 20, 2018)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 8192  --mls8192
block splitting recursion 7  --bsr7
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 3 more bytes (116958 bytes).

Verify file integrity

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

MD5:
curl --silent --compressed http://builds.emberjs.com/tags/v2.18.1/ember.min.js --location | md5sum
1dfc9b3b160fe96c812d21890b8c9e80  -
curl --silent --compressed http://minime.stephan-brumme.com/files/ember/ember-2.18.1.min.zopfli.js.gz | md5sum
1dfc9b3b160fe96c812d21890b8c9e80  -

SHA1:
curl --silent --compressed http://builds.emberjs.com/tags/v2.18.1/ember.min.js --location | sha1sum
387e2a65a4bd43941cd2d0c0b1a9bd31676e18da  -
curl --silent --compressed http://minime.stephan-brumme.com/files/ember/ember-2.18.1.min.zopfli.js.gz | sha1sum
387e2a65a4bd43941cd2d0c0b1a9bd31676e18da  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
cdnjs 123490 bytes 1dfc9b3b160fe96c812d21890b8c9e80 February 14, 2018 @ 06:04

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
116961 bytes -3 bytes zopfli --i1000000 --mls8192 --bsr7 --lazy --ohh February 20, 2018 @ 10:44
116964 bytes -6 bytes zopfli --i100000 --mls8192 --bsr7 --lazy --ohh February 16, 2018 @ 20:49
116970 bytes -23 bytes zopfli --i10000 --mls8192 --bsr7 --lazy --ohh February 14, 2018 @ 15:04
116993 bytes -27 bytes zopfli --i1000 --mls8192 --bsr7 --lazy --ohh February 14, 2018 @ 09:46
117020 bytes zopfli --i100 --mls8192 --bsr7 --lazy --ohh February 14, 2018 @ 09:41

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

Most recent activity on February 20, 2018 @ 11:10.

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
117035 117027 117028 117053 117029 117032 117031 117033 117028 117030 117025 117022 117024 117040 117078
117020 117020 117032 117030 117028 117028 117018 117023 117022 117025 117049 117022 117026 117033 117068
117029 117031 117023 117019 117024 117021 117027 117016 117018 117020 117021 117017 117083 117030 117027
117020 117020 117048 117020 117022 117028 117034 117030 117027 117021 117020 117020 116961 117014 117042
117018 117018 117037 117020 117037 117020 117016 117019 117019 117023 117017 117018 117017 117030 117040
117020 117018 117020 117019 117018 117022 117030 117018 117018 117020 117020 117021 117017 117032 117065
117019 117018 117024 117020 117027 117025 117018 117020 117030 117025 117024 117016 117016 117035 117036
117021 117016 117012 117019 117020 117027 117027 117077 117020 117019 117027 117021 117017 117031 117037
117018 117017 117018 117019 117017 117022 117020 117020 117018 117020 117016 117036 117068 117033 117065
117024 117018 117013 117022 117016 117008 117011 117025 117024 117020 117042 117033 117074 117048 117034
117029 117030 117021 117018 117009 117019 117021 117028 117021 117017 117028 117017 117018 117033 117070
117024 117022 117016 117018 117017 117023 117022 117020 117018 117021 117015 117019 117072 117029 117042
117023 117019 117017 117020 117018 117017 117013 117025 117014 117020 117025 117036 117015 117032 117027
117018 117019 117019 117020 117025 117018 117017 117014 117023 117017 117021 117018 117016 117034 117069
117024 117024 117016 117018 117015 117018 117026 117012 117019 117018 117021 117016 117016 117032 117068
117024 117028 117015 117017 117020 117017 117022 117019 117017 117018 117026 117015 117035 117032 117068
117024 117027 117013 117018 117016 117012 117021 117018 117019 117021 117017 117019 117015 117034 117071
117024 117021 117021 117020 117020 117020 117026 117025 117019 117020 117016 117025 117016 117032 117067
117024 117023 117026 117018 117015 117019 117015 117016 117016 117017 117019 117025 117018 117034 117068
117012 117014 117012 117018 117016 117016 117028 117016 117018 117017 117027 117020 117018 117031 117038
117018 117021 117017 117018 117021 117020 117021 117020 117020 117019 117025 117019 117016 117033 117067
117018 117020 117019 117018 117018 117020 117020 117012 117017 117020 117013 117018 117018 117034 117071
117023 117018 117017 117023 117017 117020 117011 117013 117019 117019 117026 117018 117016 117019 117065

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 117020 bytes 100%
1,000 116993 bytes -27 bytes 100%
10,000 116970 bytes -23 bytes 100%
100,000 116964 bytes -6 bytes 0.87%
1,000,000 116961 bytes -3 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
117131 bytes +170 bytes (+0.15%) +93 bytes
117130 bytes +169 bytes (+0.14%) +92 bytes
117096 bytes +135 bytes (+0.12%) +58 bytes
117038 bytes +77 bytes (+0.07%)
117078 bytes +117 bytes (+0.10%) +40 bytes
117080 bytes +119 bytes (+0.10%) +42 bytes
117098 bytes +137 bytes (+0.12%) +60 bytes
117060 bytes +99 bytes (+0.08%) +22 bytes
117095 bytes +134 bytes (+0.11%) +57 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 80723 bytes -36238 bytes (-30.98%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 87584 bytes -29377 bytes (-25.12%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 94009 bytes -22952 bytes (-19.62%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 100399 bytes -16562 bytes (-14.16%)
Brotli (Wikipedia) brotli brotli -q 11 102163 bytes -14798 bytes (-12.65%)
LZMA2 (Wikipedia) xz xz -9 103780 bytes -13181 bytes (-11.27%)
ZSTD (Wikipedia) zstd zstd -19 106712 bytes -10249 bytes (-8.76%)

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