BackboneJS 1.1.2 - as small as it gets (near-perfect GZIP compression)

The original file has 60997 bytes (59.6k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 19999 bytes (19.5k, 33%).

After GZIP compression these minified files vary in size:

Boot	7697 bytes (7.5k)	CDN
Baidu	6695 bytes (6.5k)	CDN
cdnjs	6692 bytes (6.5k)	CDN
gzip -6 (default)	6677 bytes (6.5k)	local copy
gzip -9	6672 bytes (6.5k)	local copy
unpkg	6664 bytes (6.5k)	CDN
Sina	6655 bytes (6.5k)	CDN
Yandex	6648 bytes (6.5k)	CDN
jsdelivr	6648 bytes (6.5k)	CDN
7zip -mx=9 -tgzip	6500 bytes (6.3k)	local copy
libdeflate -12	6489 bytes (6.3k)	local copy
zultra	6489 bytes (6.3k)	local copy
pigz -11 -n	6487 bytes (6.3k)	local copy
kzip -s0 -rn -b1	6483 bytes (6.3k)	local copy
Zopfli	6479 bytes (6.3k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-1.1.2.min.js (or via HTTPS)

You will automatically get the smallest BackboneJS 1.1.2 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 169 bytes by using my BackboneJS 1.1.2 Zopfli version instead of the best available CDN (2.61% smaller than jsdelivr, 6479 vs. 6648 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 --mls4096 --bsr6 --lazy --ohh

(found September 8, 2015)

Description	Value	Parameter
iterations	10000	--i10000
maximum blocks	8	--mb8
maximum length score	4096	--mls4096
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/1.1.2/backbone-min.js --location | md5sum
9c3e3189b75efd56066402f80c3e781b -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.1.2.min.zopfli.js.gz | md5sum
9c3e3189b75efd56066402f80c3e781b -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/1.1.2/backbone-min.js --location | sha1sum
42ef07a70aa727cd721aec4112ed0bcc94801faa -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.1.2.min.zopfli.js.gz | sha1sum
42ef07a70aa727cd721aec4112ed0bcc94801faa -

These CDNs send you the original file:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Boot	7697 bytes	9c3e3189b75efd56066402f80c3e781b	(invalid)
cdnjs	6692 bytes	9c3e3189b75efd56066402f80c3e781b	(invalid)
unpkg	6664 bytes	9c3e3189b75efd56066402f80c3e781b	July 11, 2016 @ 16:18
Sina	6655 bytes	9c3e3189b75efd56066402f80c3e781b	(invalid)
Yandex	6648 bytes	9c3e3189b75efd56066402f80c3e781b	(invalid)
jsdelivr	6648 bytes	9c3e3189b75efd56066402f80c3e781b	(invalid)

And some CDNs send you a different file:

CDN	Size (compressed)	MD5 (uncompressed)	Comment / Diff	Timestamp
Baidu	6695 bytes	c8b889d72185f4ecc1cf7f6846bdfc72	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
6479 bytes	-1 byte	zopfli --i10000 --mls4096 --bsr6 --lazy --ohh	September 8, 2015 @ 12:40
6480 bytes	-1 byte	zopfli --i1000 --mls1024 --bsr9 --lazy --ohh	September 8, 2015 @ 11:41
6481 bytes	–	zopfli --i100 --mls1024 --bsr16 --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	6483	6483	6483	6483	6483	6482	6483	6486	6484	6485	6485	6483	6482	6484	6484
4	6484	6484	6484	6486	6484	6484	6485	6484	6484	6484	6484	6481	6481	6480	6480
6	6484	6485	6484	6484	6480	6483	6485	6484	6480	6482	6483	6479	6481	6482	6482
7	6484	6484	6485	6484	6484	6484	6485	6484	6480	6480	6483	6481	6479	6482	6482
8	6484	6484	6484	6481	6484	6484	6484	6484	6484	6484	6485	6479	6481	6480	6480
9	6481	6484	6480	6481	6482	6483	6484	6484	6481	6480	6483	6481	6481	6481	6481
10	6484	6484	6483	6484	6484	6484	6484	6484	6484	6484	6483	6481	6481	6481	6481
11	6483	6484	6481	6481	6484	6484	6484	6484	6481	6481	6483	6481	6479	6480	6480
12	6484	6485	6484	6484	6484	6484	6484	6484	6484	6484	6483	6479	6479	6483	6483
13	6484	6484	6484	6481	6481	6483	6484	6484	6481	6481	6483	6479	6479	6480	6480
14	6484	6484	6483	6481	6484	6485	6485	6484	6481	6480	6483	6480	6480	6480	6480
15	6485	6484	6484	6481	6484	6484	6485	6484	6484	6480	6483	6484	6483	6482	6482
16	6484	6484	6484	6484	6484	6485	6484	6484	6481	6480	6480	6479	6480	6480	6480
17	6484	6484	6484	6483	6484	6484	6484	6484	6480	6481	6483	6482	6479	6482	6482
18	6484	6484	6484	6484	6484	6484	6485	6484	6484	6481	6483	6481	6482	6481	6481
19	6484	6485	6484	6481	6483	6484	6484	6484	6480	6480	6483	6484	6482	6482	6482
20	6484	6485	6483	6481	6481	6481	6484	6484	6480	6480	6483	6479	6481	6484	6480
21	6484	6485	6484	6483	6483	6483	6485	6484	6484	6485	6482	6479	6481	6481	6481
22	6484	6485	6484	6483	6484	6484	6485	6484	6480	6481	6483	6481	6479	6480	6480
23	6484	6484	6484	6481	6484	6484	6484	6484	6481	6480	6483	6481	6479	6481	6481
25	6484	6485	6485	6483	6484	6484	6485	6484	6484	6484	6483	6481	6481	6481	6481
30	6485	6484	6483	6484	6483	6484	6484	6484	6480	6481	6483	6481	6482	6480	6480
40	6483	6484	6481	6481	6484	6483	6484	6484	6483	6481	6483	6481	6480	6480	6480

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	6481 bytes	–	100%
1,000	6480 bytes	-1 byte	100%
10,000	6479 bytes	-1 byte	100%
100,000	6479 bytes	–	4.35%
1,000,000	6479 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)	6484 bytes	+5 bytes (+0.08%)	+1 byte
1	6483 bytes	+4 bytes (+0.06%)	–
2	6508 bytes	+29 bytes (+0.45%)	+25 bytes
3	6539 bytes	+60 bytes (+0.93%)	+56 bytes
4	6573 bytes	+94 bytes (+1.45%)	+90 bytes
5	6604 bytes	+125 bytes (+1.93%)	+121 bytes
6	6623 bytes	+144 bytes (+2.22%)	+140 bytes
7	6644 bytes	+165 bytes (+2.55%)	+161 bytes
8	6680 bytes	+201 bytes (+3.10%)	+197 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	5669 bytes	-810 bytes (-12.50%)
Brotli (Wikipedia)	brotli	brotli -q 11	6011 bytes	-468 bytes (-7.22%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	6089 bytes	-390 bytes (-6.02%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	6425 bytes	-54 bytes (-0.83%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	6444 bytes	-35 bytes (-0.54%)
Zstandard (Wikipedia)	zstd	zstd -19	6488 bytes	+9 bytes (+0.14%)
LZMA2 (Wikipedia)	xz	xz -9	6524 bytes	+45 bytes (+0.69%)

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.