BackboneJS 0.2.0 - as small as it gets (near-perfect GZIP compression)

The original file has 24751 bytes (24.2k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 7814 bytes (7.6k, 32%).

After GZIP compression these minified files vary in size:

Boot	2942 bytes (2.9k)	CDN
gzip -6 (default)	2655 bytes (2.6k)	local copy
gzip -9	2655 bytes (2.6k)	local copy
cdnjs	2644 bytes (2.6k)	CDN
unpkg	2633 bytes (2.6k)	CDN
libdeflate -12	2578 bytes (2.5k)	local copy
7zip -mx=9 -tgzip	2577 bytes (2.5k)	local copy
kzip -s0 -rn -b1	2575 bytes (2.5k)	local copy
zultra	2575 bytes (2.5k)	local copy
pigz -11 -n	2574 bytes (2.5k)	local copy
Zopfli	2573 bytes (2.5k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-0.2.0.min.js (or via HTTPS)

You will automatically get the smallest BackboneJS 0.2.0 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 60 bytes by using my BackboneJS 0.2.0 Zopfli version instead of the best available CDN (2.33% smaller than unpkg, 2573 vs. 2633 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 --i1000 --mb8 --mls512 --bsr6 --lazy --ohh

(found September 8, 2015)

Description	Value	Parameter
iterations	1000	--i1000
maximum blocks	8	--mb8
maximum length score	512	--mls512
block splitting recursion	6	--bsr6
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/0.2.0/backbone-min.js --location | md5sum
2b9be58c38587f242d383879488e668d -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-0.2.0.min.zopfli.js.gz | md5sum
2b9be58c38587f242d383879488e668d -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/0.2.0/backbone-min.js --location | sha1sum
6cb272172c500d67267bc339c60c06e79a83662a -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-0.2.0.min.zopfli.js.gz | sha1sum
6cb272172c500d67267bc339c60c06e79a83662a -

All listed CDNs deliver identical contents:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Boot	2942 bytes	2b9be58c38587f242d383879488e668d	(invalid)
cdnjs	2644 bytes	2b9be58c38587f242d383879488e668d	(invalid)
unpkg	2633 bytes	2b9be58c38587f242d383879488e668d	July 11, 2016 @ 16:18

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
2573 bytes	-1 byte	zopfli --i1000 --mls512 --bsr6 --lazy --ohh	September 8, 2015 @ 11:51
2574 bytes	–	zopfli --i100 --mls512 --bsr9 --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 20, 2020 @ 12:52.

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:
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	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
4	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
6	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
7	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
8	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
9	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
10	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
11	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
12	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
13	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
14	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
15	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
16	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
17	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
18	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
19	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
20	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
21	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
22	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
23	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
25	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
30	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573
40	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573	2573

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	2574 bytes	–	100%
1,000	2573 bytes	-1 byte	100%
10,000	2573 bytes	–	100%
100,000	2573 bytes	–	100%
1,000,000	2573 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
(any)	2575 bytes	+2 bytes (+0.08%)	–
1	2575 bytes	+2 bytes (+0.08%)	–
2	2610 bytes	+37 bytes (+1.44%)	+35 bytes
3	2638 bytes	+65 bytes (+2.53%)	+63 bytes
4	2678 bytes	+105 bytes (+4.08%)	+103 bytes
5	2716 bytes	+143 bytes (+5.56%)	+141 bytes
6	2752 bytes	+179 bytes (+6.96%)	+177 bytes
7	2776 bytes	+203 bytes (+7.89%)	+201 bytes
8	2807 bytes	+234 bytes (+9.09%)	+232 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	2317 bytes	-256 bytes (-9.95%)
Brotli (Wikipedia)	brotli	brotli -q 11	2329 bytes	-244 bytes (-9.48%)
Zstandard (Wikipedia)	zstd	zstd -19	2603 bytes	+30 bytes (+1.17%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	2639 bytes	+66 bytes (+2.57%)
LZMA2 (Wikipedia)	xz	xz -9	2680 bytes	+107 bytes (+4.16%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	2940 bytes	+367 bytes (+14.26%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	3219 bytes	+646 bytes (+25.11%)

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.