BackboneJS 0.9.10 - as small as it gets (near-perfect GZIP compression)

The original file has 55796 bytes (54.5k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 18286 bytes (17.9k, 33%).

After GZIP compression these minified files vary in size:

Boot	7160 bytes (7.0k)	CDN
Baidu	6353 bytes (6.2k)	CDN
gzip -6 (default)	6322 bytes (6.2k)	local copy
cdnjs	6321 bytes (6.2k)	CDN
jsdelivr	6320 bytes (6.2k)	CDN
unpkg	6314 bytes (6.2k)	CDN
gzip -9	6310 bytes (6.2k)	local copy
7zip -mx=9 -tgzip	6144 bytes (6.0k)	local copy
libdeflate -12	6142 bytes (6.0k)	local copy
zultra	6141 bytes (6.0k)	local copy
pigz -11 -n	6137 bytes (6.0k)	local copy
kzip -s0 -rn -b0	6136 bytes (6.0k)	local copy
Zopfli	6125 bytes (6.0k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-0.9.10.min.js (or via HTTPS)

You will automatically get the smallest BackboneJS 0.9.10 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 189 bytes by using my BackboneJS 0.9.10 Zopfli version instead of the best available CDN (3.09% smaller than unpkg, 6125 vs. 6314 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 --mls512 --bsr14 --lazy --ohh

(found November 27, 2015)

Description	Value	Parameter
iterations	1000000	--i1000000
maximum blocks	8	--mb8
maximum length score	512	--mls512
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/0.9.10/backbone-min.js --location | md5sum
44a81b4ba37828fc620b47a5c55da53e -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-0.9.10.min.zopfli.js.gz | md5sum
44a81b4ba37828fc620b47a5c55da53e -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/0.9.10/backbone-min.js --location | sha1sum
64d76035ef563288f2964fa73843634655d6043d -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-0.9.10.min.zopfli.js.gz | sha1sum
64d76035ef563288f2964fa73843634655d6043d -

These CDNs send you the original file:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Boot	7160 bytes	44a81b4ba37828fc620b47a5c55da53e	(invalid)
cdnjs	6321 bytes	44a81b4ba37828fc620b47a5c55da53e	(invalid)
unpkg	6314 bytes	44a81b4ba37828fc620b47a5c55da53e	July 11, 2016 @ 16:18

And some CDNs send you a different file:

CDN	Size (compressed)	MD5 (uncompressed)	Comment / Diff	Timestamp
Baidu	6353 bytes	c0f61ccea82807ce535917b48b6baa6d	only whitespaces differ	(invalid)
jsdelivr	6320 bytes	c0f61ccea82807ce535917b48b6baa6d	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:

1.4.1, 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
6125 bytes	-1 byte	zopfli --i1000000 --mls512 --bsr14 --lazy --ohh	November 27, 2015 @ 15:46
6126 bytes	-1 byte	zopfli --i10000 --mls512 --bsr14 --lazy --ohh	September 8, 2015 @ 13:40
6127 bytes	-2 bytes	zopfli --i1000 --mls512 --bsr14 --lazy --ohh	September 8, 2015 @ 11:47
6129 bytes	–	zopfli --i100 --mls512 --bsr4 --lazy --ohh	September 8, 2015 @ 11:35

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 @ 12:48.

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	6132	6132	6130	6132	6132	6134	6134	6135	6131	6128	6131	6135	6131	6130	6130
4	6128	6131	6131	6132	6130	6129	6126	6128	6127	6133	6131	6129	6128	6131	6131
6	6127	6130	6131	6131	6131	6126	6126	6135	6134	6127	6130	6136	6127	6131	6127
7	6128	6130	6130	6129	6139	6141	6141	6135	6134	6131	6131	6135	6127	6128	6128
8	6128	6131	6134	6130	6131	6128	6129	6135	6134	6131	6130	6135	6127	6127	6127
9	6128	6131	6131	6130	6141	6128	6141	6130	6130	6130	6128	6128	6127	6127	6128
10	6129	6131	6130	6130	6132	6127	6126	6128	6131	6131	6132	6136	6127	6128	6128
11	6128	6131	6131	6130	6141	6141	6141	6135	6130	6129	6130	6129	6127	6127	6127
12	6128	6131	6130	6131	6131	6126	6126	6130	6131	6129	6130	6129	6128	6127	6127
13	6128	6131	6130	6132	6139	6140	6141	6130	6127	6127	6131	6135	6126	6127	6128
14	6131	6131	6131	6130	6139	6140	6126	6129	6125	6129	6131	6129	6127	6128	6128
15	6129	6131	6131	6130	6139	6139	6141	6135	6130	6127	6130	6135	6127	6128	6128
16	6129	6131	6131	6130	6131	6127	6129	6130	6131	6127	6131	6129	6127	6131	6128
17	6129	6130	6131	6130	6126	6141	6141	6135	6131	6130	6130	6129	6128	6127	6128
18	6129	6131	6132	6129	6139	6139	6141	6130	6131	6129	6131	6129	6128	6128	6127
19	6129	6131	6132	6129	6131	6127	6126	6135	6126	6129	6128	6128	6127	6127	6127
20	6128	6131	6130	6130	6131	6139	6129	6128	6131	6130	6130	6136	6131	6127	6127
21	6129	6131	6132	6131	6132	6141	6141	6135	6130	6131	6130	6136	6127	6127	6127
22	6128	6131	6131	6131	6139	6128	6126	6135	6128	6129	6130	6129	6127	6127	6127
23	6128	6131	6131	6130	6130	6126	6129	6135	6130	6129	6130	6135	6131	6127	6127
25	6128	6130	6130	6130	6130	6142	6141	6135	6131	6131	6130	6129	6128	6126	6126
30	6129	6130	6131	6131	6130	6127	6127	6135	6131	6131	6131	6135	6131	6126	6129
40	6130	6131	6130	6130	6131	6126	6126	6130	6131	6131	6131	6135	6127	6128	6128

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	6128 bytes	–	100%
1,000	6127 bytes	-1 byte	100%
10,000	6126 bytes	-1 byte	100%
100,000	6126 bytes	–	5.51%
1,000,000	6125 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)	6136 bytes	+11 bytes (+0.18%)	–
1	6136 bytes	+11 bytes (+0.18%)	–
2	6154 bytes	+29 bytes (+0.47%)	+18 bytes
3	6183 bytes	+58 bytes (+0.95%)	+47 bytes
4	6196 bytes	+71 bytes (+1.16%)	+60 bytes
5	6224 bytes	+99 bytes (+1.62%)	+88 bytes
6	6260 bytes	+135 bytes (+2.20%)	+124 bytes
7	6295 bytes	+170 bytes (+2.78%)	+159 bytes
8	6327 bytes	+202 bytes (+3.30%)	+191 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	5387 bytes	-738 bytes (-12.05%)
Brotli (Wikipedia)	brotli	brotli -q 11	5604 bytes	-521 bytes (-8.51%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	5952 bytes	-173 bytes (-2.82%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	6079 bytes	-46 bytes (-0.75%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	6153 bytes	+28 bytes (+0.46%)
Zstandard (Wikipedia)	zstd	zstd -19	6156 bytes	+31 bytes (+0.51%)
LZMA2 (Wikipedia)	xz	xz -9	6180 bytes	+55 bytes (+0.90%)

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.