BackboneJS 0.9.9 - as small as it gets (near-perfect GZIP compression)

The original file has 57071 bytes (55.7k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 18303 bytes (17.9k, 32%).

After GZIP compression these minified files vary in size:

Boot	7255 bytes (7.1k)	CDN
Baidu	6479 bytes (6.3k)	CDN
cdnjs	6452 bytes (6.3k)	CDN
gzip -6 (default)	6450 bytes (6.3k)	local copy
gzip -9	6441 bytes (6.3k)	local copy
unpkg	6434 bytes (6.3k)	CDN
zultra	6264 bytes (6.1k)	local copy
7zip -mx=9 -tgzip	6261 bytes (6.1k)	local copy
pigz -11 -n	6259 bytes (6.1k)	local copy
libdeflate -12	6257 bytes (6.1k)	local copy
kzip -s0 -rn -b1	6252 bytes (6.1k)	local copy
Zopfli	6243 bytes (6.1k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-0.9.9.min.js (or via HTTPS)

You will automatically get the smallest BackboneJS 0.9.9 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 191 bytes by using my BackboneJS 0.9.9 Zopfli version instead of the best available CDN (3.06% smaller than unpkg, 6243 vs. 6434 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 --bsr11 --lazy --ohh

(found November 27, 2015)

Description	Value	Parameter
iterations	1000000	--i1000000
maximum blocks	8	--mb8
maximum length score	1024	--mls1024
block splitting recursion	11	--bsr11
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/0.9.9/backbone-min.js --location | md5sum
a4f6f23f49cf77eaef2e00d7da09342c -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-0.9.9.min.zopfli.js.gz | md5sum
a4f6f23f49cf77eaef2e00d7da09342c -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/0.9.9/backbone-min.js --location | sha1sum
d52d756f20f3c2b3e8c424e973813d448b2fd903 -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-0.9.9.min.zopfli.js.gz | sha1sum
d52d756f20f3c2b3e8c424e973813d448b2fd903 -

These CDNs send you the original file:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Boot	7255 bytes	a4f6f23f49cf77eaef2e00d7da09342c	(invalid)
cdnjs	6452 bytes	a4f6f23f49cf77eaef2e00d7da09342c	(invalid)
unpkg	6434 bytes	a4f6f23f49cf77eaef2e00d7da09342c	July 11, 2016 @ 16:18

And some CDNs send you a different file:

CDN	Size (compressed)	MD5 (uncompressed)	Comment / Diff	Timestamp
Baidu	6479 bytes	b4825a643cf8a5ebdf968ce26f7b5288	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
6243 bytes	-1 byte	zopfli --i1000000 --mls1024 --bsr11 --lazy --ohh	November 27, 2015 @ 15:03
6244 bytes	-2 bytes	zopfli --i10000 --mls1024 --bsr11 --lazy --ohh	September 8, 2015 @ 13:19
6246 bytes	-1 byte	zopfli --i1000 --mls1024 --bsr4 --lazy --ohh	September 8, 2015 @ 11:45
6247 bytes	–	zopfli --i100 --mls1024 --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 @ 12:48.

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	6247	6247	6247	6248	6252	6252	6252	6247	6248	6247	6248	6254	6249	6249	6248
4	6252	6255	6248	6246	6246	6247	6246	6247	6246	6244	6249	6255	6249	6247	6247
6	6252	6254	6253	6252	6247	6246	6247	6252	6250	6250	6255	6248	6247	6248	6248
7	6247	6248	6247	6246	6246	6247	6247	6248	6247	6244	6255	6249	6247	6247	6247
8	6247	6247	6247	6248	6247	6247	6246	6247	6247	6246	6248	6248	6247	6248	6249
9	6252	6247	6253	6252	6252	6252	6252	6247	6247	6255	6255	6249	6249	6248	6249
10	6247	6248	6247	6246	6247	6247	6246	6252	6247	6244	6246	6248	6248	6247	6249
11	6246	6248	6248	6247	6247	6247	6246	6247	6248	6243	6255	6249	6247	6248	6248
12	6246	6248	6247	6246	6246	6246	6246	6247	6247	6246	6255	6249	6247	6249	6249
13	6247	6248	6247	6246	6246	6247	6246	6247	6247	6246	6255	6249	6246	6246	6246
14	6248	6248	6248	6249	6246	6248	6247	6247	6247	6247	6249	6249	6247	6247	6247
15	6252	6247	6246	6246	6246	6248	6246	6247	6246	6244	6255	6249	6247	6247	6247
16	6246	6247	6247	6246	6246	6247	6246	6247	6248	6244	6249	6248	6246	6247	6247
17	6247	6248	6247	6248	6246	6248	6247	6248	6248	6247	6255	6248	6250	6247	6247
18	6252	6248	6247	6246	6247	6247	6246	6252	6249	6246	6247	6247	6248	6248	6247
19	6246	6247	6246	6248	6247	6247	6246	6248	6249	6244	6255	6249	6247	6247	6247
20	6248	6246	6248	6248	6246	6247	6246	6247	6249	6246	6246	6249	6248	6248	6247
21	6248	6248	6248	6249	6246	6247	6247	6248	6248	6250	6255	6248	6247	6248	6248
22	6247	6248	6248	6247	6247	6247	6247	6248	6247	6244	6246	6248	6247	6248	6248
23	6247	6247	6247	6249	6246	6247	6247	6247	6247	6244	6255	6249	6249	6248	6248
25	6248	6248	6248	6249	6246	6247	6246	6247	6247	6246	6255	6249	6247	6249	6249
30	6246	6247	6246	6246	6246	6247	6247	6247	6247	6245	6247	6248	6248	6247	6247
40	6246	6248	6247	6248	6246	6248	6246	6247	6249	6246	6246	6249	6249	6249	6249

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	6247 bytes	–	100%
1,000	6246 bytes	-1 byte	100%
10,000	6244 bytes	-2 bytes	100%
100,000	6244 bytes	–	2.61%
1,000,000	6243 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)	6252 bytes	+9 bytes (+0.14%)	–
1	6252 bytes	+9 bytes (+0.14%)	–
2	6269 bytes	+26 bytes (+0.42%)	+17 bytes
3	6282 bytes	+39 bytes (+0.62%)	+30 bytes
4	6311 bytes	+68 bytes (+1.09%)	+59 bytes
5	6338 bytes	+95 bytes (+1.52%)	+86 bytes
6	6376 bytes	+133 bytes (+2.13%)	+124 bytes
7	6412 bytes	+169 bytes (+2.71%)	+160 bytes
8	6442 bytes	+199 bytes (+3.19%)	+190 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	5461 bytes	-782 bytes (-12.53%)
Brotli (Wikipedia)	brotli	brotli -q 11	5727 bytes	-516 bytes (-8.27%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	5944 bytes	-299 bytes (-4.79%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	6150 bytes	-93 bytes (-1.49%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	6221 bytes	-22 bytes (-0.35%)
Zstandard (Wikipedia)	zstd	zstd -19	6278 bytes	+35 bytes (+0.56%)
LZMA2 (Wikipedia)	xz	xz -9	6284 bytes	+41 bytes (+0.66%)

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.