BackboneJS 1.3.1 - as small as it gets (near-perfect GZIP compression)

The original file has 72164 bytes (70.5k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 23314 bytes (22.8k, 32%).

After GZIP compression these minified files vary in size:

Boot	8804 bytes (8.6k)	CDN
cdnjs	7585 bytes (7.4k)	CDN
gzip -6 (default)	7567 bytes (7.4k)	local copy
gzip -9	7559 bytes (7.4k)	local copy
unpkg	7545 bytes (7.4k)	CDN
jsdelivr	7541 bytes (7.4k)	CDN
zultra	7335 bytes (7.2k)	local copy
pigz -11 -n	7328 bytes (7.2k)	local copy
libdeflate -12	7324 bytes (7.2k)	local copy
7zip -mx=9 -tgzip	7322 bytes (7.2k)	local copy
kzip -s0 -rn -b0	7318 bytes (7.1k)	local copy
Zopfli	7318 bytes (7.1k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-1.3.1.min.js (or via HTTPS)

You will automatically get the smallest BackboneJS 1.3.1 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 223 bytes by using my BackboneJS 1.3.1 Zopfli version instead of the best available CDN (3.05% smaller than jsdelivr, 7318 vs. 7541 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 --mls2 --bsr14 --lazy --ohh

(found March 6, 2016)

Description	Value	Parameter
iterations	1000000	--i1000000
maximum blocks	8	--mb8
maximum length score	2	--mls2
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

Verify file integrity

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

MD5:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/1.3.1/backbone-min.js --location | md5sum
f07a47de25413196efc65820e53cb0af -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.3.1.min.zopfli.js.gz | md5sum
f07a47de25413196efc65820e53cb0af -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/1.3.1/backbone-min.js --location | sha1sum
10e90b5a5b1f765759b41e87b708f7a65dd41b31 -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.3.1.min.zopfli.js.gz | sha1sum
10e90b5a5b1f765759b41e87b708f7a65dd41b31 -

All listed CDNs deliver identical contents:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Boot	8804 bytes	f07a47de25413196efc65820e53cb0af	March 7, 2016 @ 16:37
cdnjs	7585 bytes	f07a47de25413196efc65820e53cb0af	(invalid)
unpkg	7545 bytes	f07a47de25413196efc65820e53cb0af	July 11, 2016 @ 16:17
jsdelivr	7541 bytes	f07a47de25413196efc65820e53cb0af	(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
7318 bytes	-1 byte	zopfli --i1000000 --mls2 --bsr14 --lazy --ohh	March 6, 2016 @ 19:57
7319 bytes	-1 byte	zopfli --i10000 --mls2 --bsr14 --lazy --ohh	March 5, 2016 @ 09:58
7320 bytes	-1 byte	zopfli --i1000 --mls512 --bsr20 --lazy --ohh	March 5, 2016 @ 09:48
7321 bytes	–	zopfli --i100 --mls256 --bsr13 --lazy --ohh	March 5, 2016 @ 09:41

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 @ 12:56.

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, 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	7319	7319	7319	7319	7319	7318	7319	7319	7320	7320	7320	7323	7322	7322	7322
4	7327	7323	7327	7327	7322	7322	7321	7323	7324	7323	7322	7323	7322	7324	7325
6	7319	7323	7322	7323	7321	7319	7322	7323	7324	7322	7322	7321	7322	7323	7323
7	7321	7322	7321	7323	7321	7319	7321	7323	7323	7321	7321	7321	7326	7322	7325
8	7322	7323	7322	7323	7323	7319	7322	7322	7323	7321	7321	7321	7322	7322	7325
9	7318	7323	7322	7321	7322	7319	7321	7323	7323	7322	7321	7322	7323	7322	7321
10	7321	7323	7319	7320	7321	7320	7321	7323	7324	7321	7322	7321	7322	7321	7322
11	7319	7323	7322	7323	7321	7322	7319	7320	7323	7320	7321	7322	7322	7322	7322
12	7322	7323	7322	7323	7323	7323	7322	7323	7324	7321	7322	7321	7323	7321	7322
13	7322	7322	7322	7323	7323	7319	7321	7319	7323	7321	7321	7321	7321	7323	7323
14	7318	7323	7321	7319	7322	7319	7322	7323	7323	7320	7321	7321	7323	7321	7323
15	7321	7323	7321	7323	7323	7319	7322	7323	7323	7321	7321	7321	7320	7325	7325
16	7322	7322	7321	7323	7323	7319	7321	7322	7323	7322	7322	7321	7323	7323	7323
17	7321	7323	7322	7323	7323	7319	7321	7323	7323	7321	7321	7321	7322	7322	7322
18	7322	7323	7323	7320	7322	7319	7320	7323	7323	7322	7321	7322	7322	7321	7321
19	7319	7323	7322	7323	7323	7319	7321	7323	7321	7322	7322	7321	7323	7322	7324
20	7323	7323	7323	7323	7323	7320	7321	7323	7319	7322	7322	7322	7321	7322	7322
21	7318	7323	7323	7323	7321	7319	7321	7323	7323	7322	7321	7323	7322	7323	7323
22	7322	7322	7322	7323	7323	7320	7320	7323	7323	7322	7321	7322	7322	7321	7321
23	7318	7323	7322	7323	7319	7319	7321	7323	7323	7321	7322	7322	7322	7322	7322
25	7318	7323	7322	7323	7321	7320	7321	7323	7321	7321	7322	7321	7322	7322	7325
30	7321	7322	7322	7323	7323	7319	7321	7323	7323	7322	7322	7321	7322	7323	7323
40	7322	7323	7321	7324	7322	7319	7321	7323	7323	7322	7322	7321	7322	7321	7321

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	7321 bytes	–	100%
1,000	7320 bytes	-1 byte	100%
10,000	7319 bytes	-1 byte	100%
100,000	7319 bytes	–	13.91%
1,000,000	7318 bytes	-1 byte	10.72%
10,000,000	7318 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)	7318 bytes	– (0.00%)	–
1	7318 bytes	– (0.00%)	–
2	7341 bytes	+23 bytes (+0.31%)	+23 bytes
3	7368 bytes	+50 bytes (+0.68%)	+50 bytes
4	7397 bytes	+79 bytes (+1.08%)	+79 bytes
5	7416 bytes	+98 bytes (+1.34%)	+98 bytes
6	7458 bytes	+140 bytes (+1.91%)	+140 bytes
7	7488 bytes	+170 bytes (+2.32%)	+170 bytes
8	7511 bytes	+193 bytes (+2.64%)	+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	6357 bytes	-961 bytes (-13.13%)
Brotli (Wikipedia)	brotli	brotli -q 11	6840 bytes	-478 bytes (-6.53%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	6889 bytes	-429 bytes (-5.86%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	6993 bytes	-325 bytes (-4.44%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	7216 bytes	-102 bytes (-1.39%)
Zstandard (Wikipedia)	zstd	zstd -19	7309 bytes	-9 bytes (-0.12%)
LZMA2 (Wikipedia)	xz	xz -9	7336 bytes	+18 bytes (+0.25%)

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.