Choose a version:
33% The original file has 60997 bytes (59.6k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 19999 bytes (19.5k, 33%).

After GZIP compression these minified files vary in size:
Boot
  7697 bytes (7.5k)
CDN, direct link
Baidu
  6695 bytes (6.5k)
CDN, direct link
cdnjs
  6692 bytes (6.5k)
CDN, direct link
gzip -6 (default)
  6677 bytes (6.5k)
local copy
gzip -9
  6672 bytes (6.5k)
local copy
unpkg
  6664 bytes (6.5k)
CDN, direct link
Sina
  6655 bytes (6.5k)
CDN, direct link
cdnhttps
  6655 bytes (6.5k)
CDN, direct link
Yandex
  6648 bytes (6.5k)
CDN, direct link
jsdelivr
  6648 bytes (6.5k)
CDN, direct link
7zip -mx=9 -tgzip
  6500 bytes (6.3k)
local copy
libdeflate -12
  6489 bytes (6.3k)
local copy
pigz -11 -n
  6487 bytes (6.3k)
local copy
kzip -s0 -rn -b1
  6483 bytes (6.3k)
local copy
Zopfli
  6479 bytes (6.3k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-1.1.2.min.js

You will automatically get the smallest BackboneJS 1.1.2 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 169 bytes by using my BackboneJS 1.1.2 Zopfli version instead of the best available CDN (2.61% smaller than jsdelivr, 6479 vs. 6648 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 --i10000 --mb8 --mls4096 --bsr6 --lazy --ohh

(found September 8, 2015)
Description Value Parameter
iterations 10000  --i10000
maximum blocks 8  --mb8
maximum length score 4096  --mls4096
block splitting recursion 6  --bsr6
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/1.1.2/backbone-min.js --location | md5sum
9c3e3189b75efd56066402f80c3e781b  -
curl --silent --compressed http://minime.stephan-brumme.com/files/backbonejs/backbone-1.1.2.min.zopfli.js.gz | md5sum
9c3e3189b75efd56066402f80c3e781b  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/1.1.2/backbone-min.js --location | sha1sum
42ef07a70aa727cd721aec4112ed0bcc94801faa  -
curl --silent --compressed http://minime.stephan-brumme.com/files/backbonejs/backbone-1.1.2.min.zopfli.js.gz | sha1sum
42ef07a70aa727cd721aec4112ed0bcc94801faa  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 7697 bytes 9c3e3189b75efd56066402f80c3e781b (invalid)
cdnjs 6692 bytes 9c3e3189b75efd56066402f80c3e781b (invalid)
unpkg 6664 bytes 9c3e3189b75efd56066402f80c3e781b July 11, 2016 @ 16:18
Sina 6655 bytes 9c3e3189b75efd56066402f80c3e781b (invalid)
cdnhttps 6655 bytes 9c3e3189b75efd56066402f80c3e781b December 24, 2015 @ 07:32
Yandex 6648 bytes 9c3e3189b75efd56066402f80c3e781b (invalid)
jsdelivr 6648 bytes 9c3e3189b75efd56066402f80c3e781b (invalid)

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
Baidu 6695 bytes c8b889d72185f4ecc1cf7f6846bdfc72 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
6479 bytes -1 byte zopfli --i10000 --mls4096 --bsr6 --lazy --ohh September 8, 2015 @ 12:40
6480 bytes -1 byte zopfli --i1000 --mls1024 --bsr9 --lazy --ohh September 8, 2015 @ 11:41
6481 bytes zopfli --i100 --mls1024 --bsr16 --lazy --ohh September 8, 2015 @ 11:31

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
6483 6483 6483 6483 6483 6482 6483 6486 6484 6485 6485 6483 6482 6484 6484
6484 6484 6484 6486 6484 6484 6485 6484 6484 6484 6484 6481 6481 6480 6480
6484 6485 6484 6484 6480 6483 6485 6484 6480 6482 6483 6479 6481 6482 6482
6484 6484 6485 6484 6484 6484 6485 6484 6480 6480 6483 6481 6479 6482 6482
6484 6484 6484 6481 6484 6484 6484 6484 6484 6484 6485 6479 6481 6480 6480
6481 6484 6480 6481 6482 6483 6484 6484 6481 6480 6483 6481 6481 6481 6481
6484 6484 6483 6484 6484 6484 6484 6484 6484 6484 6483 6481 6481 6481 6481
6483 6484 6481 6481 6484 6484 6484 6484 6481 6481 6483 6481 6479 6480 6480
6484 6485 6484 6484 6484 6484 6484 6484 6484 6484 6483 6479 6479 6483 6483
6484 6484 6484 6481 6481 6483 6484 6484 6481 6481 6483 6479 6479 6480 6480
6484 6484 6483 6481 6484 6485 6485 6484 6481 6480 6483 6480 6480 6480 6480
6485 6484 6484 6481 6484 6484 6485 6484 6484 6480 6483 6484 6483 6482 6482
6484 6484 6484 6484 6484 6485 6484 6484 6481 6480 6480 6479 6480 6480 6480
6484 6484 6484 6483 6484 6484 6484 6484 6480 6481 6483 6482 6479 6482 6482
6484 6484 6484 6484 6484 6484 6485 6484 6484 6481 6483 6481 6482 6481 6481
6484 6485 6484 6481 6483 6484 6484 6484 6480 6480 6483 6484 6482 6482 6482
6484 6485 6483 6481 6481 6481 6484 6484 6480 6480 6483 6479 6481 6484 6480
6484 6485 6484 6483 6483 6483 6485 6484 6484 6485 6482 6479 6481 6481 6481
6484 6485 6484 6483 6484 6484 6485 6484 6480 6481 6483 6481 6479 6480 6480
6484 6484 6484 6481 6484 6484 6484 6484 6481 6480 6483 6481 6479 6481 6481
6484 6485 6485 6483 6484 6484 6485 6484 6484 6484 6483 6481 6481 6481 6481
6485 6484 6483 6484 6483 6484 6484 6484 6480 6481 6483 6481 6482 6480 6480
6483 6484 6481 6481 6484 6483 6484 6484 6483 6481 6483 6481 6480 6480 6480

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 6481 bytes 100%
1,000 6480 bytes -1 byte 100%
10,000 6479 bytes -1 byte 100%
100,000 6479 bytes 4.35%
1,000,000 6479 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
6484 bytes +5 bytes (+0.08%) +1 byte
6483 bytes +4 bytes (+0.06%)
6508 bytes +29 bytes (+0.45%) +25 bytes
6539 bytes +60 bytes (+0.93%) +56 bytes
6573 bytes +94 bytes (+1.45%) +90 bytes
6604 bytes +125 bytes (+1.93%) +121 bytes
6623 bytes +144 bytes (+2.22%) +140 bytes
6644 bytes +165 bytes (+2.55%) +161 bytes
6680 bytes +201 bytes (+3.10%) +197 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 5669 bytes -810 bytes (-12.50%)
Brotli (Wikipedia) brotli brotli -q 11 6011 bytes -468 bytes (-7.22%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 6089 bytes -390 bytes (-6.02%)
ZPAQ (Wikipedia) zpaq zpaq -method 69 6425 bytes -54 bytes (-0.83%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 6444 bytes -35 bytes (-0.54%)
ZSTD (Wikipedia) zstd zstd -19 6488 bytes +9 bytes (+0.14%)
LZMA2 (Wikipedia) xz xz -9 6524 bytes +45 bytes (+0.69%)

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