Choose a version:
32% The original file has 23824 bytes (23.3k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 7655 bytes (7.5k, 32%).

After GZIP compression these minified files vary in size:
Boot
  2909 bytes (2.8k)
CDN, direct link
gzip -6 (default)
  2631 bytes (2.6k)
local copy
gzip -9
  2628 bytes (2.6k)
local copy
cdnjs
  2625 bytes (2.6k)
CDN, direct link
cdnhttps
  2609 bytes (2.5k)
CDN, direct link
unpkg
  2607 bytes (2.5k)
CDN, direct link
libdeflate -12
  2557 bytes (2.5k)
local copy
7zip -mx=9 -tgzip
  2553 bytes (2.5k)
local copy
kzip -s0 -rn -b1
  2553 bytes (2.5k)
local copy
pigz -11 -n
  2553 bytes (2.5k)
local copy
Zopfli
  2552 bytes (2.5k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-0.1.2.min.js

You will automatically get the smallest BackboneJS 0.1.2 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 55 bytes by using my BackboneJS 0.1.2 Zopfli version instead of the best available CDN (2.16% smaller than unpkg, 2552 vs. 2607 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 --i100 --mb8 --mls2048 --bsr2 --lazy --ohh

(found September 8, 2015)
Description Value Parameter
iterations 100  --i100
maximum blocks 8  --mb8
maximum length score 2048  --mls2048
block splitting recursion 2  --bsr2
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/0.1.2/backbone-min.js --location | md5sum
baca4f0f379ca7728549143ef52740c8  -
curl --silent --compressed http://minime.stephan-brumme.com/files/backbonejs/backbone-0.1.2.min.zopfli.js.gz | md5sum
baca4f0f379ca7728549143ef52740c8  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/0.1.2/backbone-min.js --location | sha1sum
55dd76b5899e7f090d8d9f5286c48e7a593edd89  -
curl --silent --compressed http://minime.stephan-brumme.com/files/backbonejs/backbone-0.1.2.min.zopfli.js.gz | sha1sum
55dd76b5899e7f090d8d9f5286c48e7a593edd89  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 2909 bytes baca4f0f379ca7728549143ef52740c8 (invalid)
cdnjs 2625 bytes baca4f0f379ca7728549143ef52740c8 (invalid)
cdnhttps 2609 bytes baca4f0f379ca7728549143ef52740c8 December 24, 2015 @ 07:32
unpkg 2607 bytes baca4f0f379ca7728549143ef52740c8 July 11, 2016 @ 16:18

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
2552 bytes zopfli --i100 --mls2048 --bsr2 --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 or 100,000.
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
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553
2553 2553 2553 2553 2553 2553 2552 2552 2553 2553 2552 2553 2553 2553 2553

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 2552 bytes 100%
1,000 2552 bytes 100%
10,000 2552 bytes 100%
100,000 2552 bytes 0.29%
1,000,000
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
2553 bytes +1 byte (+0.04%)
2553 bytes +1 byte (+0.04%)
2588 bytes +36 bytes (+1.41%) +35 bytes
2619 bytes +67 bytes (+2.63%) +66 bytes
2657 bytes +105 bytes (+4.11%) +104 bytes
2697 bytes +145 bytes (+5.68%) +144 bytes
2732 bytes +180 bytes (+7.05%) +179 bytes
2756 bytes +204 bytes (+7.99%) +203 bytes
2789 bytes +237 bytes (+9.29%) +236 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 2301 bytes -251 bytes (-9.84%)
Brotli (Wikipedia) brotli brotli -q 11 2326 bytes -226 bytes (-8.86%)
ZSTD (Wikipedia) zstd zstd -19 2581 bytes +29 bytes (+1.14%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 2619 bytes +67 bytes (+2.63%)
LZMA2 (Wikipedia) xz xz -9 2656 bytes +104 bytes (+4.08%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 2893 bytes +341 bytes (+13.36%)
ZPAQ (Wikipedia) zpaq zpaq -method 69 3202 bytes +650 bytes (+25.47%)

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