Choose a version:
31% The original file has 53103 bytes (51.9k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 16464 bytes (16.1k, 31%).

After GZIP compression these minified files vary in size:
Boot
  6542 bytes (6.4k)
CDN, direct link
Baidu
  5827 bytes (5.7k)
CDN, direct link
cdnjs
  5797 bytes (5.7k)
CDN, direct link
gzip -6 (default)
  5782 bytes (5.6k)
local copy
gzip -9
  5779 bytes (5.6k)
local copy
unpkg
  5767 bytes (5.6k)
CDN, direct link
cdnhttps
  5760 bytes (5.6k)
CDN, direct link
libdeflate -12
  5631 bytes (5.5k)
local copy
7zip -mx=9 -tgzip
  5626 bytes (5.5k)
local copy
pigz -11 -n
  5622 bytes (5.5k)
local copy
kzip -s0 -rn -b0
  5620 bytes (5.5k)
local copy
Zopfli
  5609 bytes (5.5k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-0.9.2.min.js

You will automatically get the smallest BackboneJS 0.9.2 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 151 bytes by using my BackboneJS 0.9.2 Zopfli version instead of the best available CDN (2.69% smaller than cdnhttps, 5609 vs. 5760 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 --bsr22 --lazy --ohh

(found November 27, 2015)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 8192  --mls8192
block splitting recursion 22  --bsr22
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/0.9.2/backbone-min.js --location | md5sum
9f8b43fd1df78dca0827c73e29890865  -
curl --silent --compressed http://minime.stephan-brumme.com/files/backbonejs/backbone-0.9.2.min.zopfli.js.gz | md5sum
9f8b43fd1df78dca0827c73e29890865  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/0.9.2/backbone-min.js --location | sha1sum
bdbfc587072f9af9100dd28e55e22911ed359df7  -
curl --silent --compressed http://minime.stephan-brumme.com/files/backbonejs/backbone-0.9.2.min.zopfli.js.gz | sha1sum
bdbfc587072f9af9100dd28e55e22911ed359df7  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 6542 bytes 9f8b43fd1df78dca0827c73e29890865 (invalid)
cdnjs 5797 bytes 9f8b43fd1df78dca0827c73e29890865 (invalid)
unpkg 5767 bytes 9f8b43fd1df78dca0827c73e29890865 July 11, 2016 @ 16:18
cdnhttps 5760 bytes 9f8b43fd1df78dca0827c73e29890865 December 24, 2015 @ 07:32

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
Baidu 5827 bytes 49ff81bf752a77eb5a23ea10283b4bae 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
5609 bytes -2 bytes zopfli --i1000000 --mls8192 --bsr22 --lazy --ohh November 27, 2015 @ 14:35
5611 bytes -1 byte zopfli --i1000 --mls8192 --bsr22 --lazy --ohh September 21, 2015 @ 23:58
5612 bytes -1 byte zopfli --i10000 --mls512 --bsr11 --lazy --ohh September 8, 2015 @ 13:26
5613 bytes -1 byte zopfli --i1000 --mls512 --bsr11 --lazy --ohh September 8, 2015 @ 11:46
5614 bytes -1 byte zopfli --i1000 --mls512 --bsr13 --lazy --ohh September 8, 2015 @ 11:46
5615 bytes zopfli --i100 --mls1024 --bsr8 --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 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
5619 5619 5614 5619 5619 5614 5615 5616 5619 5619 5619 5614 5613 5612 5612
5619 5612 5616 5615 5616 5615 5614 5613 5619 5619 5619 5620 5613 5617 5617
5619 5614 5614 5615 5615 5613 5616 5612 5619 5613 5619 5619 5613 5614 5614
5619 5614 5616 5615 5614 5614 5615 5613 5613 5613 5619 5613 5613 5615 5615
5619 5617 5617 5615 5613 5613 5615 5613 5613 5612 5619 5620 5613 5612 5612
5619 5615 5616 5616 5615 5614 5616 5614 5614 5613 5619 5620 5616 5615 5615
5619 5614 5616 5616 5614 5616 5616 5612 5612 5613 5619 5613 5613 5616 5616
5619 5615 5616 5615 5616 5615 5616 5613 5612 5613 5619 5613 5613 5613 5613
5619 5614 5617 5615 5615 5615 5616 5613 5619 5612 5619 5613 5613 5614 5614
5619 5614 5614 5618 5613 5614 5613 5614 5612 5613 5619 5613 5613 5615 5615
5619 5612 5616 5616 5613 5612 5615 5612 5613 5619 5619 5620 5613 5615 5615
5619 5614 5617 5615 5615 5614 5613 5613 5613 5613 5619 5613 5613 5613 5613
5619 5615 5616 5616 5615 5616 5616 5619 5619 5613 5619 5613 5613 5613 5613
5619 5616 5616 5615 5612 5613 5615 5612 5619 5613 5619 5613 5613 5613 5613
5619 5614 5614 5615 5616 5612 5613 5614 5613 5612 5619 5619 5613 5613 5613
5619 5614 5616 5615 5615 5616 5616 5614 5613 5613 5619 5613 5613 5613 5613
5619 5614 5616 5615 5616 5615 5616 5614 5612 5612 5619 5619 5613 5613 5613
5619 5612 5616 5615 5616 5616 5616 5619 5619 5612 5619 5620 5613 5613 5613
5619 5614 5616 5612 5613 5616 5616 5612 5613 5613 5619 5613 5609 5613 5613
5619 5614 5612 5612 5613 5615 5612 5614 5613 5613 5619 5613 5613 5613 5613
5619 5617 5616 5615 5615 5615 5616 5612 5612 5613 5619 5619 5613 5613 5613
5619 5615 5616 5615 5616 5615 5616 5612 5619 5612 5619 5620 5613 5613 5613
5619 5612 5616 5616 5613 5612 5612 5613 5613 5619 5619 5613 5613 5615 5615

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 5613 bytes 100%
1,000 5611 bytes -2 bytes 100%
10,000 5611 bytes 100%
100,000 5611 bytes 0.29%
1,000,000 5609 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
5620 bytes +11 bytes (+0.20%)
5620 bytes +11 bytes (+0.20%)
5650 bytes +41 bytes (+0.73%) +30 bytes
5684 bytes +75 bytes (+1.34%) +64 bytes
5692 bytes +83 bytes (+1.48%) +72 bytes
5729 bytes +120 bytes (+2.14%) +109 bytes
5765 bytes +156 bytes (+2.78%) +145 bytes
5788 bytes +179 bytes (+3.19%) +168 bytes
5825 bytes +216 bytes (+3.85%) +205 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 4955 bytes -654 bytes (-11.66%)
Brotli (Wikipedia) brotli brotli -q 11 5139 bytes -470 bytes (-8.38%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 5324 bytes -285 bytes (-5.08%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 5607 bytes -2 bytes (-0.04%)
ZSTD (Wikipedia) zstd zstd -19 5638 bytes +29 bytes (+0.52%)
LZMA2 (Wikipedia) xz xz -9 5684 bytes +75 bytes (+1.34%)
ZPAQ (Wikipedia) zpaq zpaq -method 69 5782 bytes +173 bytes (+3.08%)

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