Choose a version:
32% The original file has 78181 bytes (76.3k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 25200 bytes (24.6k, 32%).

After GZIP compression these minified files vary in size:
unpkg
  10200 bytes (10.0k)
CDN
jsdelivr
  8188 bytes (8.0k)
CDN
gzip -6 (default)
  8044 bytes (7.9k)
local copy
gzip -9
  8032 bytes (7.8k)
local copy
Boot
  8029 bytes (7.8k)
CDN
cdnjs
  8020 bytes (7.8k)
CDN
zultra
  7793 bytes (7.6k)
local copy
libdeflate -12
  7784 bytes (7.6k)
local copy
7zip -mx=9 -tgzip
  7783 bytes (7.6k)
local copy
pigz -11 -n
  7783 bytes (7.6k)
local copy
kzip -s0 -rn -b0
  7781 bytes (7.6k)
local copy
Zopfli
  7776 bytes (7.6k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-1.4.1.min.js (or via HTTPS)

You will automatically get the smallest BackboneJS 1.4.1 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 244 bytes by using my BackboneJS 1.4.1 Zopfli version instead of the best available CDN (3.14% smaller than cdnjs, 7776 vs. 8020 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 --mls512 --bsr20 --lazy --ohh

(found March 21, 2022)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 512  --mls512
block splitting recursion 20  --bsr20
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/1.4.1/backbone-min.js --location | md5sum
9b0a6dd82088805382155bd283301fe7  -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.4.1.min.zopfli.js.gz | md5sum
9b0a6dd82088805382155bd283301fe7  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/1.4.1/backbone-min.js --location | sha1sum
349da661de6c8a36e7e61c31df2516bf80321394  -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.4.1.min.zopfli.js.gz | sha1sum
349da661de6c8a36e7e61c31df2516bf80321394  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
unpkg 10200 bytes 9b0a6dd82088805382155bd283301fe7 (invalid)
Boot 8029 bytes 9b0a6dd82088805382155bd283301fe7 March 21, 2022 @ 10:36
cdnjs 8020 bytes 9b0a6dd82088805382155bd283301fe7 (invalid)

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
jsdelivr 8188 bytes 43e2d4b0e82170cc55e5343bf3ef813b < (function(r){var n=typeof self=="object"&&self.self===self [...]
< //# sourceMappingURL=backbone-min.js.map
> /**
> * Minified by jsDelivr using Terser v5.10.0.
> * Original file: /npm/backbone@1.4.1/backbone.js
> *
> * Do NOT use SRI with dynamically generated files! More i [...]
> */
> !function(t){var e="object"==typeof self&&self.self===self [...]
> //# sourceMappingURL=/sm/257d7ea98c6e5fed07b55c249c3eb275e [...]
March 21, 2022 @ 10:36

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

Other Versions

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

1.4.1, 1.4.0,
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
7776 bytes -1 byte zopfli --i100000 --mls512 --bsr20 --lazy --ohh March 21, 2022 @ 11:16
7777 bytes -1 byte zopfli --i10000 --mls512 --bsr20 --lazy --ohh March 21, 2022 @ 10:47
7778 bytes -1 byte zopfli --i1000 --mls512 --bsr20 --lazy --ohh March 21, 2022 @ 10:46
7779 bytes zopfli --i100 --mls2048 --bsr14 --lazy --ohh March 21, 2022 @ 10:36

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

Most recent activity on March 22, 2022 @ 09:01.

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
7784 7784 7785 7784 7785 7784 7784 7785 7784 7784 7784 7779 7780 7780 7780
7779 7780 7780 7779 7780 7781 7778 7779 7778 7778 7778 7783 7780 7779 7779
7779 7781 7779 7780 7780 7780 7780 7780 7780 7779 7780 7780 7779 7778 7776
7779 7781 7779 7779 7780 7780 7778 7780 7780 7779 7778 7779 7778 7779 7780
7779 7780 7780 7779 7780 7780 7778 7779 7780 7779 7778 7780 7779 7778 7778
7780 7780 7779 7780 7779 7780 7778 7779 7779 7778 7780 7780 7778 7778 7778
7780 7780 7780 7780 7781 7781 7777 7779 7779 7779 7778 7779 7779 7776 7777
7780 7781 7780 7779 7780 7780 7780 7779 7776 7777 7780 7780 7780 7779 7776
7779 7781 7780 7779 7780 7778 7779 7779 7780 7776 7778 7780 7780 7778 7779
7781 7781 7780 7780 7780 7778 7779 7779 7780 7779 7780 7780 7778 7778 7778
7780 7780 7780 7779 7780 7779 7779 7779 7780 7780 7778 7780 7779 7778 7778
7779 7780 7780 7779 7780 7779 7779 7779 7778 7777 7778 7780 7778 7782 7778
7780 7779 7779 7779 7780 7780 7780 7779 7780 7779 7781 7781 7778 7779 7776
7779 7780 7780 7779 7780 7779 7780 7779 7779 7779 7780 7780 7779 7779 7778
7780 7780 7780 7779 7780 7780 7779 7779 7779 7777 7778 7780 7779 7778 7778
7781 7780 7780 7780 7779 7780 7780 7780 7780 7779 7780 7780 7778 7778 7778
7781 7779 7781 7780 7780 7780 7778 7779 7776 7776 7778 7780 7778 7776 7776
7780 7780 7780 7779 7780 7780 7780 7779 7780 7779 7780 7780 7779 7778 7776
7779 7779 7780 7780 7780 7780 7779 7779 7780 7779 7778 7780 7778 7778 7776
7781 7781 7779 7779 7780 7780 7778 7779 7780 7779 7780 7780 7779 7778 7777
7779 7781 7780 7780 7780 7780 7779 7779 7779 7777 7778 7780 7779 7778 7776
7781 7779 7779 7781 7781 7780 7779 7779 7779 7778 7781 7780 7779 7779 7778
7779 7781 7780 7780 7780 7781 7778 7779 7779 7779 7778 7779 7779 7776 7776

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 7779 bytes 100%
1,000 7778 bytes -1 byte 100%
10,000 7777 bytes -1 byte 100%
100,000 7776 bytes -1 byte 6.38%
1,000,000 7776 bytes 4.35%
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
7781 bytes +5 bytes (+0.06%)
7781 bytes +5 bytes (+0.06%)
7805 bytes +29 bytes (+0.37%) +24 bytes
7832 bytes +56 bytes (+0.72%) +51 bytes
7862 bytes +86 bytes (+1.11%) +81 bytes
7890 bytes +114 bytes (+1.47%) +109 bytes
7901 bytes +125 bytes (+1.61%) +120 bytes
7942 bytes +166 bytes (+2.13%) +161 bytes
7971 bytes +195 bytes (+2.51%) +190 bytes

Non-DEFLATE Algorithms

Archivers based on completely different compression algorithms often produce superior results.
Unfortunately, browsers only support gzip compression at the moment.
However, support for Brotli is constantly growing - for example, your browser actually supports it !
Algorithm Program Parameters Size Compared To Best Zopfli
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 6733 bytes -1043 bytes (-13.41%)
Brotli (Wikipedia) brotli brotli -q 11 7259 bytes -517 bytes (-6.65%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 7335 bytes -441 bytes (-5.67%)
ZPAQ (Wikipedia) zpaq zpaq -method 69 7338 bytes -438 bytes (-5.63%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 7645 bytes -131 bytes (-1.68%)
Zstandard (Wikipedia) zstd zstd -19 7740 bytes -36 bytes (-0.46%)
LZMA2 (Wikipedia) xz xz -9 7772 bytes -4 bytes (-0.05%)

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 2022.
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

All trademarks are property of their respective owners. You know, the boring legal stuff.