Choose a version:
33% The original file has 55796 bytes (54.5k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 18286 bytes (17.9k, 33%).

After GZIP compression these minified files vary in size:
Boot
  7160 bytes (7.0k)
CDN, direct link
Baidu
  6353 bytes (6.2k)
CDN, direct link
gzip -6 (default)
  6322 bytes (6.2k)
local copy
cdnjs
  6321 bytes (6.2k)
CDN, direct link
jsdelivr
  6320 bytes (6.2k)
CDN, direct link
unpkg
  6314 bytes (6.2k)
CDN, direct link
gzip -9
  6310 bytes (6.2k)
local copy
cdnhttps
  6299 bytes (6.2k)
CDN, direct link
7zip -mx=9 -tgzip
  6144 bytes (6.0k)
local copy
libdeflate -12
  6142 bytes (6.0k)
local copy
pigz -11 -n
  6137 bytes (6.0k)
local copy
kzip -s0 -rn -b0
  6136 bytes (6.0k)
local copy
Zopfli
  6125 bytes (6.0k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-0.9.10.min.js

You will automatically get the smallest BackboneJS 0.9.10 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 174 bytes by using my BackboneJS 0.9.10 Zopfli version instead of the best available CDN (2.84% smaller than cdnhttps, 6125 vs. 6299 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 --mls512 --bsr14 --lazy --ohh

(found November 27, 2015)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 512  --mls512
block splitting recursion 14  --bsr14
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://raw.githubusercontent.com/jashkenas/backbone/0.9.10/backbone-min.js --location | md5sum
44a81b4ba37828fc620b47a5c55da53e  -
curl --silent --compressed http://minime.stephan-brumme.com/files/backbonejs/backbone-0.9.10.min.zopfli.js.gz | md5sum
44a81b4ba37828fc620b47a5c55da53e  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/0.9.10/backbone-min.js --location | sha1sum
64d76035ef563288f2964fa73843634655d6043d  -
curl --silent --compressed http://minime.stephan-brumme.com/files/backbonejs/backbone-0.9.10.min.zopfli.js.gz | sha1sum
64d76035ef563288f2964fa73843634655d6043d  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 7160 bytes 44a81b4ba37828fc620b47a5c55da53e (invalid)
cdnjs 6321 bytes 44a81b4ba37828fc620b47a5c55da53e (invalid)
unpkg 6314 bytes 44a81b4ba37828fc620b47a5c55da53e July 11, 2016 @ 16:18
cdnhttps 6299 bytes 44a81b4ba37828fc620b47a5c55da53e December 24, 2015 @ 07:32

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
Baidu 6353 bytes c0f61ccea82807ce535917b48b6baa6d only whitespaces differ (invalid)
jsdelivr 6320 bytes c0f61ccea82807ce535917b48b6baa6d only whitespaces differ (invalid)

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

Other Versions

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

1.3.3, 1.3.2, 1.3.1, 1.3.0,
1.2.3, 1.2.2, 1.2.1, 1.2.0,
1.1.2, 1.1.1, 1.1.0,
1.0.0,
0.9.10, 0.9.9, 0.9.2, 0.9.1, 0.9.0,
0.3.3, 0.3.2, 0.3.1, 0.3.0,
0.2.0,
0.1.2, 0.1.1

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

Changelog

Best Zopfli parameters so far:
Size Improvement Parameters Found
6125 bytes -1 byte zopfli --i1000000 --mls512 --bsr14 --lazy --ohh November 27, 2015 @ 15:46
6126 bytes -1 byte zopfli --i10000 --mls512 --bsr14 --lazy --ohh September 8, 2015 @ 13:40
6127 bytes -2 bytes zopfli --i1000 --mls512 --bsr14 --lazy --ohh September 8, 2015 @ 11:47
6129 bytes zopfli --i100 --mls512 --bsr4 --lazy --ohh September 8, 2015 @ 11:35

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

Most recent activity on July 11, 2016 @ 16:18.

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
6132 6132 6130 6132 6132 6134 6134 6135 6131 6128 6131 6135 6131 6130 6130
6128 6131 6131 6132 6130 6129 6126 6128 6127 6133 6131 6129 6128 6131 6131
6127 6130 6131 6131 6131 6126 6126 6135 6134 6127 6130 6136 6127 6131 6127
6128 6130 6130 6129 6139 6141 6141 6135 6134 6131 6131 6135 6127 6128 6128
6128 6131 6134 6130 6131 6128 6129 6135 6134 6131 6130 6135 6127 6127 6127
6128 6131 6131 6130 6141 6128 6141 6130 6130 6130 6128 6128 6127 6127 6128
6129 6131 6130 6130 6132 6127 6126 6128 6131 6131 6132 6136 6127 6128 6128
6128 6131 6131 6130 6141 6141 6141 6135 6130 6129 6130 6129 6127 6127 6127
6128 6131 6130 6131 6131 6126 6126 6130 6131 6129 6130 6129 6128 6127 6127
6128 6131 6130 6132 6139 6140 6141 6130 6127 6127 6131 6135 6126 6127 6128
6131 6131 6131 6130 6139 6140 6126 6129 6125 6129 6131 6129 6127 6128 6128
6129 6131 6131 6130 6139 6139 6141 6135 6130 6127 6130 6135 6127 6128 6128
6129 6131 6131 6130 6131 6127 6129 6130 6131 6127 6131 6129 6127 6131 6128
6129 6130 6131 6130 6126 6141 6141 6135 6131 6130 6130 6129 6128 6127 6128
6129 6131 6132 6129 6139 6139 6141 6130 6131 6129 6131 6129 6128 6128 6127
6129 6131 6132 6129 6131 6127 6126 6135 6126 6129 6128 6128 6127 6127 6127
6128 6131 6130 6130 6131 6139 6129 6128 6131 6130 6130 6136 6131 6127 6127
6129 6131 6132 6131 6132 6141 6141 6135 6130 6131 6130 6136 6127 6127 6127
6128 6131 6131 6131 6139 6128 6126 6135 6128 6129 6130 6129 6127 6127 6127
6128 6131 6131 6130 6130 6126 6129 6135 6130 6129 6130 6135 6131 6127 6127
6128 6130 6130 6130 6130 6142 6141 6135 6131 6131 6130 6129 6128 6126 6126
6129 6130 6131 6131 6130 6127 6127 6135 6131 6131 6131 6135 6131 6126 6129
6130 6131 6130 6130 6131 6126 6126 6130 6131 6131 6131 6135 6127 6128 6128

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 6128 bytes 100%
1,000 6127 bytes -1 byte 100%
10,000 6126 bytes -1 byte 100%
100,000 6126 bytes 5.51%
1,000,000 6125 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
6136 bytes +11 bytes (+0.18%)
6136 bytes +11 bytes (+0.18%)
6154 bytes +29 bytes (+0.47%) +18 bytes
6183 bytes +58 bytes (+0.95%) +47 bytes
6196 bytes +71 bytes (+1.16%) +60 bytes
6224 bytes +99 bytes (+1.62%) +88 bytes
6260 bytes +135 bytes (+2.20%) +124 bytes
6295 bytes +170 bytes (+2.78%) +159 bytes
6327 bytes +202 bytes (+3.30%) +191 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
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 5387 bytes -738 bytes (-12.05%)
Brotli (Wikipedia) brotli brotli -q 11 5604 bytes -521 bytes (-8.51%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 5952 bytes -173 bytes (-2.82%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 6079 bytes -46 bytes (-0.75%)
ZPAQ (Wikipedia) zpaq zpaq -method 69 6153 bytes +28 bytes (+0.46%)
ZSTD (Wikipedia) zstd zstd -19 6156 bytes +31 bytes (+0.51%)
LZMA2 (Wikipedia) xz xz -9 6180 bytes +55 bytes (+0.90%)

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