BackboneJS 1.2.3 - as small as it gets (near-perfect GZIP compression)

The original file has 71415 bytes (69.7k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 23097 bytes (22.6k, 32%).

After GZIP compression these minified files vary in size:

Boot	8733 bytes (8.5k)	CDN
cdnjs	7536 bytes (7.4k)	CDN
gzip -6 (default)	7511 bytes (7.3k)	local copy
gzip -9	7504 bytes (7.3k)	local copy
fastcdn	7499 bytes (7.3k)	CDN
unpkg	7499 bytes (7.3k)	CDN
Yandex	7486 bytes (7.3k)	CDN
jsdelivr	7486 bytes (7.3k)	CDN
libdeflate -12	7304 bytes (7.1k)	local copy
zultra	7284 bytes (7.1k)	local copy
pigz -11 -n	7278 bytes (7.1k)	local copy
7zip -mx=9 -tgzip	7273 bytes (7.1k)	local copy
Zopfli	7267 bytes (7.1k)	local copy
kzip -s0 -rn -b0	7265 bytes (7.1k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-1.2.3.min.js (or via HTTPS)

You will automatically get the smallest BackboneJS 1.2.3 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 219 bytes by using my BackboneJS 1.2.3 Zopfli version instead of the best available CDN (3.01% smaller than jsdelivr, 7267 vs. 7486 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 --i100000 --mb8 --mls1024 --bsr8 --lazy --ohh

(found September 8, 2015)

Description	Value	Parameter
iterations	100000	--i100000
maximum blocks	8	--mb8
maximum length score	1024	--mls1024
block splitting recursion	8	--bsr8
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/1.2.3/backbone-min.js --location | md5sum
bac416c324a009ab62240b20609ee313 -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.2.3.min.zopfli.js.gz | md5sum
bac416c324a009ab62240b20609ee313 -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/1.2.3/backbone-min.js --location | sha1sum
124b4a2c0a3b18702a52afbda1eb6da40bececd5 -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.2.3.min.zopfli.js.gz | sha1sum
124b4a2c0a3b18702a52afbda1eb6da40bececd5 -

All listed CDNs deliver identical contents:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Boot	8733 bytes	bac416c324a009ab62240b20609ee313	(invalid)
cdnjs	7536 bytes	bac416c324a009ab62240b20609ee313	(invalid)
fastcdn	7499 bytes	bac416c324a009ab62240b20609ee313	(invalid)
unpkg	7499 bytes	bac416c324a009ab62240b20609ee313	July 11, 2016 @ 16:18
Yandex	7486 bytes	bac416c324a009ab62240b20609ee313	(invalid)
jsdelivr	7486 bytes	bac416c324a009ab62240b20609ee313	(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
7267 bytes	-1 byte	zopfli --i100000 --mls1024 --bsr8 --lazy --ohh	September 8, 2015 @ 18:08
7268 bytes	-1 byte	zopfli --i10000 --mls512 --bsr2 --lazy --ohh	September 8, 2015 @ 11:53
7269 bytes	–	zopfli --i100 --mls512 --bsr2 --lazy --ohh	September 8, 2015 @ 11:32

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 @ 12:54.

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, 1,000,000 or 10,000,000.

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	7269	7268	7268	7268	7268	7273	7268	7278	7268	7268	7270	7269	7269	7268	7268
4	7268	7268	7274	7276	7275	7269	7273	7275	7276	7271	7269	7269	7270	7271	7270
6	7270	7270	7268	7267	7268	7275	7269	7275	7271	7270	7270	7269	7270	7270	7270
7	7268	7268	7268	7269	7275	7275	7270	7274	7269	7271	7268	7269	7269	7270	7270
8	7268	7269	7268	7270	7271	7277	7268	7278	7269	7267	7268	7269	7268	7271	7271
9	7268	7269	7268	7270	7271	7268	7269	7269	7270	7270	7270	7268	7271	7271	7271
10	7267	7269	7268	7268	7275	7268	7269	7267	7269	7271	7268	7268	7268	7270	7270
11	7268	7270	7268	7269	7270	7271	7272	7267	7269	7271	7268	7269	7271	7271	7270
12	7268	7269	7273	7269	7274	7275	7273	7274	7271	7271	7269	7268	7271	7270	7271
13	7268	7269	7268	7269	7274	7275	7268	7273	7271	7271	7268	7269	7271	7271	7271
14	7269	7268	7268	7269	7268	7271	7268	7268	7271	7270	7269	7269	7270	7270	7270
15	7267	7268	7268	7268	7275	7275	7269	7274	7270	7271	7270	7269	7270	7271	7270
16	7268	7271	7281	7268	7269	7271	7268	7267	7271	7270	7270	7268	7271	7270	7271
17	7268	7269	7267	7269	7268	7275	7268	7274	7271	7271	7268	7269	7268	7271	7272
18	7268	7269	7280	7269	7268	7268	7268	7271	7270	7271	7268	7268	7269	7271	7270
19	7268	7268	7268	7270	7269	7271	7269	7269	7270	7271	7269	7270	7270	7271	7270
20	7268	7269	7269	7270	7270	7275	7268	7269	7269	7270	7269	7268	7270	7270	7270
21	7268	7268	7268	7269	7269	7269	7268	7269	7268	7271	7270	7268	7269	7271	7271
22	7268	7270	7268	7269	7269	7275	7268	7274	7271	7271	7268	7269	7269	7271	7271
23	7268	7268	7268	7269	7269	7275	7268	7269	7269	7270	7268	7268	7271	7271	7271
25	7268	7269	7268	7271	7270	7268	7268	7273	7269	7271	7268	7268	7269	7271	7271
30	7267	7269	7267	7278	7275	7268	7268	7268	7270	7271	7269	7269	7269	7270	7268
40	7268	7271	7268	7269	7275	7275	7269	7275	7269	7271	7269	7268	7271	7271	7271

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	7269 bytes	–	100%
1,000	7268 bytes	-1 byte	100%
10,000	7268 bytes	–	100%
100,000	7267 bytes	-1 byte	100%
1,000,000	7267 bytes	–	7.83%
10,000,000	7267 bytes	–	0.29%

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)	7265 bytes	-2 bytes (-0.03%)	–
1	7265 bytes	-2 bytes (-0.03%)	–
2	7298 bytes	+31 bytes (+0.43%)	+33 bytes
3	7340 bytes	+73 bytes (+1.00%)	+75 bytes
4	7353 bytes	+86 bytes (+1.18%)	+88 bytes
5	7381 bytes	+114 bytes (+1.57%)	+116 bytes
6	7412 bytes	+145 bytes (+2.00%)	+147 bytes
7	7427 bytes	+160 bytes (+2.20%)	+162 bytes
8	7458 bytes	+191 bytes (+2.63%)	+193 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	6303 bytes	-964 bytes (-13.27%)
Brotli (Wikipedia)	brotli	brotli -q 11	6796 bytes	-471 bytes (-6.48%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	6808 bytes	-459 bytes (-6.32%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	6940 bytes	-327 bytes (-4.50%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	7169 bytes	-98 bytes (-1.35%)
Zstandard (Wikipedia)	zstd	zstd -19	7257 bytes	-10 bytes (-0.14%)
LZMA2 (Wikipedia)	xz	xz -9	7284 bytes	+17 bytes (+0.23%)

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.