Choose a version:
32% The original file has 71024 bytes (69.4k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 22810 bytes (22.3k, 32%).

After GZIP compression these minified files vary in size:
Boot
  8689 bytes (8.5k)
CDN, direct link
cdnjs
  7522 bytes (7.3k)
CDN, direct link
gzip -6 (default)
  7495 bytes (7.3k)
local copy
gzip -9
  7486 bytes (7.3k)
local copy
unpkg
  7480 bytes (7.3k)
CDN, direct link
cdnhttps
  7473 bytes (7.3k)
CDN, direct link
jsdelivr
  7468 bytes (7.3k)
CDN, direct link
7zip -mx=9 -tgzip
  7259 bytes (7.1k)
local copy
libdeflate -12
  7250 bytes (7.1k)
local copy
pigz -11 -n
  7250 bytes (7.1k)
local copy
kzip -s0 -rn -b1
  7243 bytes (7.1k)
local copy
Zopfli
  7242 bytes (7.1k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-1.2.0.min.js

You will automatically get the smallest BackboneJS 1.2.0 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 226 bytes by using my BackboneJS 1.2.0 Zopfli version instead of the best available CDN (3.12% smaller than jsdelivr, 7242 vs. 7468 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 --i100000 --mb8 --mls128 --bsr14 --lazy --ohh

(found November 18, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 128  --mls128
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/1.2.0/backbone-min.js --location | md5sum
85f7529d40aa7690189d05a524c2828e  -
curl --silent --compressed http://minime.stephan-brumme.com/files/backbonejs/backbone-1.2.0.min.zopfli.js.gz | md5sum
85f7529d40aa7690189d05a524c2828e  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/1.2.0/backbone-min.js --location | sha1sum
d511a7a34dd62f15aa00fe13283ef90d7ac9cbfa  -
curl --silent --compressed http://minime.stephan-brumme.com/files/backbonejs/backbone-1.2.0.min.zopfli.js.gz | sha1sum
d511a7a34dd62f15aa00fe13283ef90d7ac9cbfa  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 8689 bytes 85f7529d40aa7690189d05a524c2828e (invalid)
cdnjs 7522 bytes 85f7529d40aa7690189d05a524c2828e (invalid)
unpkg 7480 bytes 85f7529d40aa7690189d05a524c2828e July 11, 2016 @ 16:18
cdnhttps 7473 bytes 85f7529d40aa7690189d05a524c2828e December 24, 2015 @ 07:32
jsdelivr 7468 bytes 85f7529d40aa7690189d05a524c2828e (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
7242 bytes -1 byte zopfli --i100000 --mls128 --bsr14 --lazy --ohh November 18, 2015 @ 07:38
7243 bytes -1 byte zopfli --i1000 --mls2048 --bsr13 --lazy --ohh September 8, 2015 @ 11:40
7244 bytes -1 byte zopfli --i1000 --mls1024 --bsr4 --lazy --ohh September 8, 2015 @ 11:40
7245 bytes zopfli --i100 --mls2048 --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, 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
7244 7249 7244 7245 7244 7246 7247 7246 7248 7245 7244 7244 7244 7245 7245
7252 7252 7252 7245 7250 7253 7244 7244 7249 7243 7245 7244 7244 7244 7244
7250 7247 7244 7248 7244 7249 7246 7251 7251 7244 7245 7242 7248 7244 7245
7244 7244 7248 7249 7244 7249 7244 7244 7251 7244 7246 7255 7247 7245 7246
7250 7244 7246 7248 7246 7246 7243 7246 7250 7244 7243 7244 7246 7245 7245
7248 7248 7250 7248 7251 7253 7246 7245 7250 7246 7244 7242 7244 7245 7244
7244 7245 7246 7249 7246 7249 7248 7252 7247 7246 7246 7242 7246 7244 7246
7250 7244 7250 7249 7251 7249 7244 7245 7243 7246 7245 7243 7247 7245 7246
7244 7244 7247 7244 7244 7248 7245 7251 7247 7243 7245 7242 7246 7244 7247
7244 7244 7251 7248 7250 7246 7245 7251 7251 7243 7243 7242 7244 7244 7245
7247 7247 7244 7249 7244 7253 7242 7244 7247 7243 7243 7244 7247 7245 7246
7244 7245 7243 7244 7246 7244 7244 7244 7251 7244 7246 7242 7247 7245 7245
7247 7245 7243 7248 7254 7248 7245 7251 7248 7244 7247 7242 7247 7245 7247
7250 7248 7248 7249 7248 7250 7242 7246 7251 7246 7246 7244 7246 7244 7246
7246 7244 7246 7249 7252 7247 7242 7251 7248 7245 7245 7242 7247 7245 7247
7244 7246 7246 7249 7250 7252 7244 7251 7248 7244 7244 7242 7246 7245 7246
7244 7244 7246 7248 7244 7249 7245 7244 7251 7244 7245 7242 7244 7245 7247
7248 7244 7246 7247 7244 7249 7245 7244 7244 7244 7245 7242 7247 7244 7246
7244 7245 7246 7248 7252 7248 7245 7251 7251 7244 7243 7242 7246 7245 7246
7248 7245 7249 7250 7250 7248 7245 7251 7248 7244 7246 7242 7247 7244 7246
7250 7247 7249 7248 7250 7248 7244 7251 7247 7244 7245 7242 7247 7245 7245
7250 7245 7247 7248 7244 7248 7244 7247 7251 7246 7246 7242 7246 7245 7244
7247 7245 7246 7247 7244 7249 7242 7247 7251 7245 7246 7244 7247 7245 7244

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 7245 bytes 100%
1,000 7243 bytes -2 bytes 100%
10,000 7243 bytes 100%
100,000 7242 bytes -1 byte 14.49%
1,000,000 7242 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
7243 bytes +1 byte (+0.01%)
7243 bytes +1 byte (+0.01%)
7276 bytes +34 bytes (+0.47%) +33 bytes
7305 bytes +63 bytes (+0.87%) +62 bytes
7342 bytes +100 bytes (+1.38%) +99 bytes
7356 bytes +114 bytes (+1.57%) +113 bytes
7386 bytes +144 bytes (+1.99%) +143 bytes
7404 bytes +162 bytes (+2.24%) +161 bytes
7435 bytes +193 bytes (+2.67%) +192 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 6321 bytes -921 bytes (-12.72%)
Brotli (Wikipedia) brotli brotli -q 11 6768 bytes -474 bytes (-6.55%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 6803 bytes -439 bytes (-6.06%)
ZPAQ (Wikipedia) zpaq zpaq -method 69 6953 bytes -289 bytes (-3.99%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 7135 bytes -107 bytes (-1.48%)
ZSTD (Wikipedia) zstd zstd -19 7238 bytes -4 bytes (-0.06%)
LZMA2 (Wikipedia) xz xz -9 7264 bytes +22 bytes (+0.30%)

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