BackboneJS 1.3.3 - as small as it gets (near-perfect GZIP compression)

The original file has 72236 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 23355 bytes (22.8k, 32%).

After GZIP compression these minified files vary in size:

Boot	8830 bytes (8.6k)	CDN
cdnjs	7603 bytes (7.4k)	CDN
gzip -6 (default)	7582 bytes (7.4k)	local copy
gzip -9	7576 bytes (7.4k)	local copy
unpkg	7563 bytes (7.4k)	CDN
jsdelivr	7559 bytes (7.4k)	CDN
zultra	7353 bytes (7.2k)	local copy
pigz -11 -n	7343 bytes (7.2k)	local copy
libdeflate -12	7341 bytes (7.2k)	local copy
7zip -mx=9 -tgzip	7339 bytes (7.2k)	local copy
Zopfli	7335 bytes (7.2k)	local copy
kzip -s0 -rn -b1	7334 bytes (7.2k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-1.3.3.min.js (or via HTTPS)

You will automatically get the smallest BackboneJS 1.3.3 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 224 bytes by using my BackboneJS 1.3.3 Zopfli version instead of the best available CDN (3.05% smaller than jsdelivr, 7335 vs. 7559 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 --mls32768 --bsr22 --lazy --ohh

(found March 29, 2016)

Description	Value	Parameter
iterations	100000	--i100000
maximum blocks	8	--mb8
maximum length score	32768	--mls32768
block splitting recursion	22	--bsr22
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/1.3.3/backbone-min.js --location | md5sum
1f542a03bb9e6203b95cc9d0c39e0af7 -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.3.3.min.zopfli.js.gz | md5sum
1f542a03bb9e6203b95cc9d0c39e0af7 -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/1.3.3/backbone-min.js --location | sha1sum
cedae44e9eb034dd29fd414e89f2a123773d10f4 -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.3.3.min.zopfli.js.gz | sha1sum
cedae44e9eb034dd29fd414e89f2a123773d10f4 -

All listed CDNs deliver identical contents:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Boot	8830 bytes	1f542a03bb9e6203b95cc9d0c39e0af7	May 3, 2016 @ 10:56
cdnjs	7603 bytes	1f542a03bb9e6203b95cc9d0c39e0af7	April 5, 2016 @ 20:16
unpkg	7563 bytes	1f542a03bb9e6203b95cc9d0c39e0af7	July 11, 2016 @ 16:17
jsdelivr	7559 bytes	1f542a03bb9e6203b95cc9d0c39e0af7	April 5, 2016 @ 22:38

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
7335 bytes	-1 byte	zopfli --i100000 --mls32768 --bsr22 --lazy --ohh	March 29, 2016 @ 12:17
7336 bytes	-1 byte	zopfli --i10000 --mls32768 --bsr22 --lazy --ohh	March 29, 2016 @ 12:09
7337 bytes	–	zopfli --i100 --mls16384 --bsr13 --lazy --ohh	March 29, 2016 @ 12:04

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 @ 12:50.

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	7339	7338	7337	7338	7338	7338	7338	7338	7339	7339	7339	7339	7337	7337	7337
4	7339	7344	7340	7339	7339	7339	7339	7345	7340	7338	7338	7339	7338	7341	7341
6	7338	7338	7338	7341	7342	7339	7339	7342	7339	7338	7337	7337	7339	7342	7342
7	7339	7336	7339	7339	7339	7339	7339	7339	7340	7338	7339	7337	7344	7339	7339
8	7340	7338	7339	7338	7338	7338	7339	7343	7338	7338	7337	7337	7344	7337	7337
9	7338	7336	7338	7339	7339	7339	7339	7339	7338	7338	7337	7339	7344	7339	7342
10	7338	7339	7340	7342	7339	7339	7339	7343	7338	7338	7337	7337	7343	7337	7335
11	7339	7340	7340	7339	7338	7339	7339	7338	7339	7338	7337	7337	7339	7338	7338
12	7338	7337	7339	7338	7340	7339	7342	7342	7338	7338	7337	7337	7337	7335	7340
13	7338	7337	7339	7338	7339	7339	7339	7342	7337	7338	7339	7337	7339	7335	7338
14	7338	7337	7339	7339	7339	7339	7339	7342	7338	7339	7335	7337	7338	7340	7339
15	7336	7337	7339	7338	7340	7339	7338	7343	7339	7337	7339	7335	7337	7339	7340
16	7338	7337	7338	7338	7341	7339	7339	7343	7339	7338	7338	7335	7337	7339	7335
17	7336	7338	7339	7339	7339	7339	7342	7342	7337	7338	7337	7337	7344	7342	7339
18	7338	7338	7338	7338	7340	7339	7339	7343	7338	7338	7337	7337	7337	7338	7339
19	7338	7337	7338	7339	7340	7339	7339	7342	7338	7338	7337	7337	7338	7339	7339
20	7338	7337	7339	7338	7340	7339	7342	7342	7339	7338	7337	7337	7339	7342	7342
21	7338	7336	7340	7340	7340	7339	7337	7338	7337	7338	7337	7337	7337	7340	7338
22	7338	7337	7340	7340	7340	7339	7339	7342	7338	7338	7337	7338	7343	7337	7335
23	7338	7337	7339	7338	7342	7339	7339	7345	7338	7338	7337	7337	7338	7337	7337
25	7338	7337	7340	7340	7340	7339	7342	7342	7337	7338	7337	7337	7337	7335	7339
30	7337	7337	7342	7339	7342	7338	7342	7342	7339	7338	7339	7337	7342	7339	7340
40	7338	7337	7338	7338	7340	7338	7339	7343	7337	7338	7338	7337	7338	7337	7337

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	7337 bytes	–	100%
1,000	7336 bytes	-1 byte	100%
10,000	7336 bytes	–	100%
100,000	7335 bytes	-1 byte	4.06%
1,000,000	7335 bytes	–	2.61%
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)	7334 bytes	-1 byte (-0.01%)	–
1	7334 bytes	-1 byte (-0.01%)	–
2	7356 bytes	+21 bytes (+0.29%)	+22 bytes
3	7384 bytes	+49 bytes (+0.67%)	+50 bytes
4	7414 bytes	+79 bytes (+1.08%)	+80 bytes
5	7428 bytes	+93 bytes (+1.27%)	+94 bytes
6	7471 bytes	+136 bytes (+1.85%)	+137 bytes
7	7503 bytes	+168 bytes (+2.29%)	+169 bytes
8	7529 bytes	+194 bytes (+2.64%)	+195 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	6371 bytes	-964 bytes (-13.14%)
Brotli (Wikipedia)	brotli	brotli -q 11	6863 bytes	-472 bytes (-6.43%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	6901 bytes	-434 bytes (-5.92%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	7000 bytes	-335 bytes (-4.57%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	7231 bytes	-104 bytes (-1.42%)
Zstandard (Wikipedia)	zstd	zstd -19	7325 bytes	-10 bytes (-0.14%)
LZMA2 (Wikipedia)	xz	xz -9	7352 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.