BackboneJS 0.9.1 - as small as it gets (near-perfect GZIP compression)

The original file has 49275 bytes (48.1k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 15922 bytes (15.5k, 32%).

After GZIP compression these minified files vary in size:

jsdelivr	6546 bytes (6.4k)	CDN
Boot	6319 bytes (6.2k)	CDN
Baidu	5608 bytes (5.5k)	CDN
cdnjs	5587 bytes (5.5k)	CDN
gzip -6 (default)	5575 bytes (5.4k)	local copy
gzip -9	5572 bytes (5.4k)	local copy
unpkg	5556 bytes (5.4k)	CDN
libdeflate -12	5419 bytes (5.3k)	local copy
7zip -mx=9 -tgzip	5418 bytes (5.3k)	local copy
zultra	5418 bytes (5.3k)	local copy
kzip -s0 -rn -b1	5415 bytes (5.3k)	local copy
pigz -11 -n	5413 bytes (5.3k)	local copy
Zopfli	5408 bytes (5.3k)	local copy
Zopfli (defluff)	5407 bytes (5.3k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-0.9.1.min.js (or via HTTPS)

You will automatically get the smallest BackboneJS 0.9.1 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 148 bytes by using my BackboneJS 0.9.1 Zopfli version instead of the best available CDN (2.74% smaller than unpkg, 5408 vs. 5556 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 --mls1024 --bsr14 --lazy --ohh

(found November 27, 2015)

Description	Value	Parameter
iterations	1000000	--i1000000
maximum blocks	8	--mb8
maximum length score	1024	--mls1024
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

Even Smaller Files Thanks To Defluff

Zopfli's output can be further optimized by the defluff tool.
In this particular case, defluff saves 1 more byte (5407 bytes).

Download

Verify file integrity

After decompression, my uncompressed files are identical to the original ones:

MD5:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/0.9.1/backbone-min.js --location | md5sum
6291d846b4058bd9e2f962c53288af87 -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-0.9.1.min.zopfli.js.gz | md5sum
6291d846b4058bd9e2f962c53288af87 -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/0.9.1/backbone-min.js --location | sha1sum
dff93cf89bba4d3869f9805d1c0af9d97260afdd -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-0.9.1.min.zopfli.js.gz | sha1sum
dff93cf89bba4d3869f9805d1c0af9d97260afdd -

These CDNs send you the original file:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Boot	6319 bytes	6291d846b4058bd9e2f962c53288af87	(invalid)
cdnjs	5587 bytes	6291d846b4058bd9e2f962c53288af87	(invalid)
unpkg	5556 bytes	6291d846b4058bd9e2f962c53288af87	July 11, 2016 @ 16:18

And some CDNs send you a different file:

CDN	Size (compressed)	MD5 (uncompressed)	Comment / Diff	Timestamp
jsdelivr	6546 bytes	c0f61ccea82807ce535917b48b6baa6d	< // Backbone.js 0.9.1 > // Backbone.js 0.9.10 < (function(){var i=this,r=i.Backbone,s=Array.prototype.slic [...] < {});var f=d.tail\|\|(d.tail=d.next={});f.callback=b;f.contex [...] < event:b}),(c=d[b])&&a.push({next:c.next,tail:c.tail});for( [...] < {silent:!0}))throw Error("Can't create an invalid model"); [...] < this.attributes[a]},set:function(a,b,c){var d,e;f.isObject [...] < a,this._changing&&!f.isEqual(this._changed[e],a)&&(this.tr [...] < e,f){if(!b.set(b.parse(d,f),a))return!1;c&&c(b,d)};a.error [...] < k,c);b=this.isNew()?"create":"update";b=(this.sync\|\|g.sync [...] [...]	(invalid)
Baidu	5608 bytes	be4f09a44ff38325e673eaf87e09bb60	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
5408 bytes	-1 byte	zopfli --i1000000 --mls1024 --bsr14 --lazy --ohh	November 27, 2015 @ 14:41
5409 bytes	-1 byte	zopfli --i1000 --mls1024 --bsr14 --lazy --ohh	September 8, 2015 @ 11:48
5410 bytes	–	zopfli --i100 --mls512 --bsr11 --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 @ 12:43.

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	5415	5415	5415	5415	5415	5415	5415	5415	5413	5415	5416	5411	5412	5412	5412
4	5413	5413	5415	5415	5415	5414	5415	5415	5415	5414	5416	5410	5417	5410	5410
6	5412	5412	5413	5413	5411	5411	5415	5418	5409	5410	5416	5409	5409	5409	5409
7	5410	5410	5415	5415	5411	5411	5411	5415	5411	5410	5416	5409	5409	5411	5411
8	5415	5415	5415	5415	5411	5411	5410	5416	5409	5410	5416	5411	5412	5411	5411
9	5413	5413	5412	5412	5411	5412	5410	5417	5409	5410	5416	5409	5409	5409	5409
10	5412	5412	5412	5412	5411	5411	5411	5418	5409	5410	5416	5409	5409	5409	5409
11	5408	5408	5412	5413	5410	5411	5410	5415	5409	5410	5416	5409	5410	5412	5412
12	5410	5410	5413	5415	5411	5411	5410	5415	5409	5410	5416	5409	5410	5409	5409
13	5412	5412	5409	5415	5411	5411	5411	5412	5410	5411	5416	5409	5410	5410	5410
14	5412	5412	5411	5415	5411	5411	5410	5412	5409	5408	5416	5409	5409	5411	5411
15	5413	5413	5411	5415	5411	5411	5410	5412	5409	5410	5416	5409	5409	5411	5411
16	5410	5410	5415	5415	5415	5411	5410	5417	5409	5410	5416	5409	5416	5409	5409
17	5412	5412	5411	5415	5411	5411	5410	5416	5409	5410	5416	5410	5411	5411	5411
18	5410	5410	5413	5413	5410	5411	5410	5416	5409	5410	5416	5409	5409	5409	5409
19	5413	5413	5409	5413	5411	5411	5410	5412	5409	5410	5416	5409	5409	5411	5411
20	5411	5411	5412	5412	5411	5411	5415	5417	5410	5410	5416	5411	5409	5409	5409
21	5415	5415	5410	5415	5415	5411	5415	5417	5409	5410	5416	5410	5410	5412	5412
22	5410	5410	5412	5412	5408	5411	5410	5411	5409	5410	5416	5409	5409	5411	5411
23	5410	5410	5411	5415	5411	5411	5410	5417	5409	5410	5416	5409	5409	5409	5409
25	5410	5410	5413	5412	5415	5411	5415	5416	5409	5409	5416	5409	5409	5411	5411
30	5408	5408	5412	5415	5415	5417	5415	5417	5411	5410	5416	5410	5409	5412	5412
40	5410	5410	5412	5413	5408	5411	5410	5416	5410	5410	5416	5409	5409	5409	5409

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	5410 bytes	–	100%
1,000	5409 bytes	-1 byte	100%
10,000	5409 bytes	–	100%
100,000	5408 bytes	-1 byte	21.45%
1,000,000	5408 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)	5415 bytes	+7 bytes (+0.13%)	–
1	5415 bytes	+7 bytes (+0.13%)	–
2	5444 bytes	+36 bytes (+0.67%)	+29 bytes
3	5478 bytes	+70 bytes (+1.29%)	+63 bytes
4	5493 bytes	+85 bytes (+1.57%)	+78 bytes
5	5536 bytes	+128 bytes (+2.37%)	+121 bytes
6	5574 bytes	+166 bytes (+3.07%)	+159 bytes
7	5600 bytes	+192 bytes (+3.55%)	+185 bytes
8	5635 bytes	+227 bytes (+4.20%)	+220 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	4776 bytes	-632 bytes (-11.69%)
Brotli (Wikipedia)	brotli	brotli -q 11	4945 bytes	-463 bytes (-8.56%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	5423 bytes	+15 bytes (+0.28%)
Zstandard (Wikipedia)	zstd	zstd -19	5445 bytes	+37 bytes (+0.68%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	5460 bytes	+52 bytes (+0.96%)
LZMA2 (Wikipedia)	xz	xz -9	5504 bytes	+96 bytes (+1.78%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	5585 bytes	+177 bytes (+3.27%)

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.