BackboneJS 0.3.1 - as small as it gets (near-perfect GZIP compression)

The original file has 33956 bytes (33.2k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 10958 bytes (10.7k, 32%).

After GZIP compression these minified files vary in size:

Boot	4214 bytes (4.1k)	CDN
gzip -6 (default)	3756 bytes (3.7k)	local copy
cdnjs	3754 bytes (3.7k)	CDN
gzip -9	3753 bytes (3.7k)	local copy
unpkg	3731 bytes (3.6k)	CDN
libdeflate -12	3659 bytes (3.6k)	local copy
zultra	3658 bytes (3.6k)	local copy
7zip -mx=9 -tgzip	3653 bytes (3.6k)	local copy
pigz -11 -n	3653 bytes (3.6k)	local copy
kzip -s0 -rn -b1	3651 bytes (3.6k)	local copy
Zopfli	3650 bytes (3.6k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-0.3.1.min.js (or via HTTPS)

You will automatically get the smallest BackboneJS 0.3.1 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 81 bytes by using my BackboneJS 0.3.1 Zopfli version instead of the best available CDN (2.22% smaller than unpkg, 3650 vs. 3731 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 --i10000 --mb8 --mls512 --bsr6 --lazy --ohh

(found September 8, 2015)

Description	Value	Parameter
iterations	10000	--i10000
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/0.3.1/backbone-min.js --location | md5sum
24006d96fb84506958f2e88e4d5933e4 -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-0.3.1.min.zopfli.js.gz | md5sum
24006d96fb84506958f2e88e4d5933e4 -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/0.3.1/backbone-min.js --location | sha1sum
7c01acd36fa76aeb2449a0bf0682eee40523be99 -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-0.3.1.min.zopfli.js.gz | sha1sum
7c01acd36fa76aeb2449a0bf0682eee40523be99 -

CDN	Size (compressed)	MD5 (uncompressed)	Comment / Diff	Timestamp
Boot	4214 bytes	083308c10210d6677b1ef19756279206	< e.View.extend=m;var s={create:"POST",update:"PUT","delete" [...] < function(t){t.setRequestHeader("X-HTTP-Method-Override",i) [...] > e.View.extend=m;var s={create:"POST",update:"PUT","delete" [...] > function(i){i.setRequestHeader("X-HTTP-Method-Override",g) [...]	(invalid)
cdnjs	3754 bytes	083308c10210d6677b1ef19756279206	< e.View.extend=m;var s={create:"POST",update:"PUT","delete" [...] < function(t){t.setRequestHeader("X-HTTP-Method-Override",i) [...] > e.View.extend=m;var s={create:"POST",update:"PUT","delete" [...] > function(i){i.setRequestHeader("X-HTTP-Method-Override",g) [...]	(invalid)
unpkg	3731 bytes	083308c10210d6677b1ef19756279206	< e.View.extend=m;var s={create:"POST",update:"PUT","delete" [...] < function(t){t.setRequestHeader("X-HTTP-Method-Override",i) [...] > e.View.extend=m;var s={create:"POST",update:"PUT","delete" [...] > function(i){i.setRequestHeader("X-HTTP-Method-Override",g) [...]	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
3650 bytes	-1 byte	zopfli --i10000 --mls512 --bsr6 --lazy --ohh	September 8, 2015 @ 14:21
3651 bytes	-2 bytes	zopfli --i1000 --mls512 --bsr8 --lazy --ohh	September 8, 2015 @ 11:50
3653 bytes	–	zopfli --i100 --mls2048 --bsr13 --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 @ 12:51.

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:
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	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
4	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
6	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
7	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
8	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
9	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
10	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
11	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
12	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
13	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
14	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
15	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
16	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
17	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
18	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
19	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
20	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
21	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
22	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
23	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
25	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
30	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650
40	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650	3650

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	3651 bytes	–	100%
1,000	3651 bytes	–	100%
10,000	3650 bytes	-1 byte	100%
100,000	3650 bytes	–	100%
1,000,000	3650 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)	3652 bytes	+2 bytes (+0.05%)	+1 byte
1	3651 bytes	+1 byte (+0.03%)	–
2	3678 bytes	+28 bytes (+0.77%)	+27 bytes
3	3716 bytes	+66 bytes (+1.81%)	+65 bytes
4	3729 bytes	+79 bytes (+2.16%)	+78 bytes
5	3768 bytes	+118 bytes (+3.23%)	+117 bytes
6	3809 bytes	+159 bytes (+4.36%)	+158 bytes
7	3841 bytes	+191 bytes (+5.23%)	+190 bytes
8	3872 bytes	+222 bytes (+6.08%)	+221 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	3273 bytes	-377 bytes (-10.33%)
Brotli (Wikipedia)	brotli	brotli -q 11	3297 bytes	-353 bytes (-9.67%)
Zstandard (Wikipedia)	zstd	zstd -19	3668 bytes	+18 bytes (+0.49%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	3687 bytes	+37 bytes (+1.01%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	3716 bytes	+66 bytes (+1.81%)
LZMA2 (Wikipedia)	xz	xz -9	3728 bytes	+78 bytes (+2.14%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	4113 bytes	+463 bytes (+12.68%)

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.