BackboneJS 1.2.2 - as small as it gets (near-perfect GZIP compression)

The original file has 71365 bytes (69.7k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 23062 bytes (22.5k, 32%).

After GZIP compression these minified files vary in size:

Boot	8712 bytes (8.5k)	CDN
cdnjs	7521 bytes (7.3k)	CDN
gzip -6 (default)	7496 bytes (7.3k)	local copy
gzip -9	7488 bytes (7.3k)	local copy
unpkg	7485 bytes (7.3k)	CDN
jsdelivr	7470 bytes (7.3k)	CDN
libdeflate -12	7287 bytes (7.1k)	local copy
zultra	7269 bytes (7.1k)	local copy
pigz -11 -n	7261 bytes (7.1k)	local copy
7zip -mx=9 -tgzip	7257 bytes (7.1k)	local copy
Zopfli	7252 bytes (7.1k)	local copy
kzip -s0 -rn -b0	7251 bytes (7.1k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-1.2.2.min.js (or via HTTPS)

You will automatically get the smallest BackboneJS 1.2.2 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 218 bytes by using my BackboneJS 1.2.2 Zopfli version instead of the best available CDN (3.01% smaller than jsdelivr, 7252 vs. 7470 bytes):

Download

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 --mls4096 --bsr9 --lazy --ohh

(found November 27, 2015)

Description	Value	Parameter
iterations	1000000	--i1000000
maximum blocks	8	--mb8
maximum length score	4096	--mls4096
block splitting recursion	9	--bsr9
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/1.2.2/backbone-min.js --location | md5sum
f633f1a2a8ebc39a3ffffbf9e6418bcb -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.2.2.min.zopfli.js.gz | md5sum
f633f1a2a8ebc39a3ffffbf9e6418bcb -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/1.2.2/backbone-min.js --location | sha1sum
1c3a7a8b88d907e6c291e861f084d3efd39b583d -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.2.2.min.zopfli.js.gz | sha1sum
1c3a7a8b88d907e6c291e861f084d3efd39b583d -

All listed CDNs deliver identical contents:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Boot	8712 bytes	f633f1a2a8ebc39a3ffffbf9e6418bcb	(invalid)
cdnjs	7521 bytes	f633f1a2a8ebc39a3ffffbf9e6418bcb	(invalid)
unpkg	7485 bytes	f633f1a2a8ebc39a3ffffbf9e6418bcb	July 11, 2016 @ 16:18
jsdelivr	7470 bytes	f633f1a2a8ebc39a3ffffbf9e6418bcb	(invalid)

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
7252 bytes	-1 byte	zopfli --i1000000 --mls4096 --bsr9 --lazy --ohh	November 27, 2015 @ 16:50
7253 bytes	-1 byte	zopfli --i10000 --mls4096 --bsr9 --lazy --ohh	September 8, 2015 @ 12:07
7254 bytes	-1 byte	zopfli --i1000 --mls1024 --bsr6 --lazy --ohh	September 8, 2015 @ 11:38
7255 bytes	–	zopfli --i100 --mls1024 --bsr11 --lazy --ohh	September 8, 2015 @ 11:32

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

Most recent activity on July 20, 2020 @ 12:51.

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
2	7254	7254	7255	7254	7254	7255	7254	7254	7262	7254	7253	7254	7256	7255	7255
4	7254	7255	7258	7260	7261	7256	7259	7259	7259	7254	7254	7255	7256	7255	7255
6	7256	7255	7254	7255	7255	7254	7258	7259	7254	7254	7254	7254	7255	7254	7255
7	7253	7256	7254	7255	7259	7254	7254	7258	7254	7256	7256	7254	7257	7254	7255
8	7254	7255	7254	7254	7254	7254	7254	7253	7259	7256	7256	7254	7255	7255	7255
9	7254	7255	7255	7255	7254	7257	7260	7255	7254	7258	7254	7252	7255	7255	7255
10	7254	7256	7255	7255	7259	7254	7254	7259	7253	7256	7254	7254	7254	7257	7257
11	7254	7255	7254	7254	7254	7254	7258	7254	7258	7254	7256	7254	7256	7257	7255
12	7253	7256	7254	7255	7255	7255	7254	7254	7254	7256	7255	7254	7255	7257	7256
13	7254	7255	7258	7255	7261	7254	7254	7254	7254	7254	7253	7253	7254	7253	7255
14	7254	7254	7255	7254	7255	7259	7264	7253	7254	7256	7254	7253	7255	7254	7255
15	7254	7255	7254	7255	7261	7256	7258	7258	7254	7256	7256	7255	7257	7254	7254
16	7254	7256	7255	7254	7255	7254	7264	7254	7255	7256	7253	7253	7256	7255	7255
17	7254	7256	7255	7255	7255	7257	7258	7253	7263	7255	7256	7254	7254	7255	7255
18	7255	7254	7267	7255	7255	7257	7258	7254	7255	7256	7255	7254	7254	7254	7254
19	7254	7255	7254	7255	7255	7256	7256	7254	7255	7253	7253	7254	7257	7257	7254
20	7254	7255	7254	7255	7255	7256	7258	7254	7255	7254	7256	7255	7257	7254	7254
21	7254	7255	7254	7255	7255	7255	7258	7254	7255	7256	7254	7254	7254	7254	7253
22	7254	7255	7254	7255	7255	7254	7258	7260	7255	7254	7254	7254	7255	7254	7255
23	7255	7255	7254	7255	7255	7255	7259	7254	7254	7255	7253	7254	7257	7257	7255
25	7254	7255	7254	7255	7255	7254	7254	7259	7255	7256	7254	7254	7256	7254	7255
30	7254	7255	7254	7254	7255	7256	7256	7254	7254	7256	7254	7254	7257	7254	7254
40	7254	7256	7254	7255	7255	7254	7255	7258	7255	7256	7255	7254	7254	7255	7255

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	7254 bytes	–	100%
1,000	7254 bytes	–	100%
10,000	7253 bytes	-1 byte	100%
100,000	7253 bytes	–	20.29%
1,000,000	7252 bytes	-1 byte	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
(any)	7251 bytes	-1 byte (-0.01%)	–
1	7251 bytes	-1 byte (-0.01%)	–
2	7274 bytes	+22 bytes (+0.30%)	+23 bytes
3	7303 bytes	+51 bytes (+0.70%)	+52 bytes
4	7332 bytes	+80 bytes (+1.10%)	+81 bytes
5	7348 bytes	+96 bytes (+1.32%)	+97 bytes
6	7389 bytes	+137 bytes (+1.89%)	+138 bytes
7	7419 bytes	+167 bytes (+2.30%)	+168 bytes
8	7449 bytes	+197 bytes (+2.72%)	+198 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	6289 bytes	-963 bytes (-13.28%)
Brotli (Wikipedia)	brotli	brotli -q 11	6786 bytes	-466 bytes (-6.43%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	6794 bytes	-458 bytes (-6.32%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	6929 bytes	-323 bytes (-4.45%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	7149 bytes	-103 bytes (-1.42%)
Zstandard (Wikipedia)	zstd	zstd -19	7239 bytes	-13 bytes (-0.18%)
LZMA2 (Wikipedia)	xz	xz -9	7264 bytes	+12 bytes (+0.17%)

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):

Load and Parse Data

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 2026.
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.