BackboneJS 1.4.0 - as small as it gets (near-perfect GZIP compression)

The original file has 77794 bytes (76.0k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 25006 bytes (24.4k, 32%).

After GZIP compression these minified files vary in size:

unpkg	9537 bytes (9.3k)	CDN
jsdelivr	8147 bytes (8.0k)	CDN
Boot	8038 bytes (7.8k)	CDN
cdnjs	8038 bytes (7.8k)	CDN
gzip -6 (default)	8018 bytes (7.8k)	local copy
gzip -9	8005 bytes (7.8k)	local copy
7zip -mx=9 -tgzip	7771 bytes (7.6k)	local copy
zultra	7764 bytes (7.6k)	local copy
libdeflate -12	7755 bytes (7.6k)	local copy
pigz -11 -n	7755 bytes (7.6k)	local copy
kzip -s0 -rn -b1	7749 bytes (7.6k)	local copy
Zopfli	7746 bytes (7.6k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-1.4.0.min.js (or via HTTPS)

You will automatically get the smallest BackboneJS 1.4.0 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 292 bytes by using my BackboneJS 1.4.0 Zopfli version instead of the best available CDN (3.77% smaller than cdnjs, 7746 vs. 8038 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 --mls64 --bsr12 --lazy --ohh

(found February 21, 2019)

Description	Value	Parameter
iterations	100000	--i100000
maximum blocks	8	--mb8
maximum length score	64	--mls64
block splitting recursion	12	--bsr12
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/1.4.0/backbone-min.js --location | md5sum
93a2e442d9ea4e6bfc6fe8789d7277f6 -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.4.0.min.zopfli.js.gz | md5sum
93a2e442d9ea4e6bfc6fe8789d7277f6 -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/1.4.0/backbone-min.js --location | sha1sum
d7a331dfccce646eb5662a18960f183bf687f49c -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.4.0.min.zopfli.js.gz | sha1sum
d7a331dfccce646eb5662a18960f183bf687f49c -

These CDNs send you the original file:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
unpkg	9537 bytes	93a2e442d9ea4e6bfc6fe8789d7277f6	(invalid)
Boot	8038 bytes	93a2e442d9ea4e6bfc6fe8789d7277f6	(invalid)
cdnjs	8038 bytes	93a2e442d9ea4e6bfc6fe8789d7277f6	(invalid)

And some CDNs send you a different file:

CDN	Size (compressed)	MD5 (uncompressed)	Comment / Diff	Timestamp
jsdelivr	8147 bytes	0042c2cdbbc9a4649c6777e73434114c	< (function(t){var e=typeof self=="object"&&self.self===self [...] < //# sourceMappingURL=backbone-min.map > /** > * Minified by jsDelivr using Terser v3.14.1. > * Original file: /npm/backbone@1.4.0/backbone.js > * > * Do NOT use SRI with dynamically generated files! More i [...] > */ > !function(t){var e="object"==typeof self&&self.self===self [...] > //# sourceMappingURL=/sm/d26e532d1bfd2944378654fa1bd8b554e [...]	December 1, 2019 @ 05:20

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
7746 bytes	-1 byte	zopfli --i100000 --mls64 --bsr12 --lazy --ohh	February 21, 2019 @ 09:38
7747 bytes	-1 byte	zopfli --i1000 --mls128 --bsr8 --lazy --ohh	February 20, 2019 @ 12:52
7748 bytes	–	zopfli --i100 --mls4 --bsr20 --lazy --ohh	February 20, 2019 @ 12:45

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 @ 12:53.

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	7751	7751	7751	7751	7752	7752	7751	7751	7751	7749	7749	7749	7749	7750	7751
4	7748	7747	7746	7749	7747	7748	7747	7749	7747	7751	7748	7749	7752	7749	7748
6	7747	7747	7747	7752	7748	7751	7748	7751	7748	7750	7748	7749	7749	7748	7748
7	7747	7746	7747	7747	7747	7747	7746	7749	7747	7747	7748	7748	7748	7748	7753
8	7748	7748	7747	7748	7747	7752	7746	7749	7748	7751	7748	7749	7748	7749	7748
9	7747	7747	7748	7748	7749	7749	7748	7751	7748	7751	7749	7751	7748	7749	7751
10	7747	7747	7746	7748	7748	7748	7746	7749	7747	7751	7748	7748	7749	7749	7749
11	7747	7747	7747	7748	7748	7746	7747	7751	7748	7751	7748	7749	7749	7750	7749
12	7746	7748	7747	7752	7747	7746	7746	7749	7746	7748	7748	7749	7749	7749	7749
13	7746	7747	7747	7747	7747	7751	7747	7751	7748	7749	7748	7749	7748	7749	7749
14	7746	7746	7747	7753	7751	7747	7747	7749	7747	7751	7749	7751	7749	7749	7748
15	7747	7747	7747	7748	7747	7747	7747	7749	7746	7751	7748	7749	7749	7749	7748
16	7747	7746	7748	7747	7747	7747	7746	7749	7748	7747	7749	7753	7749	7749	7750
17	7747	7746	7747	7748	7747	7747	7749	7746	7746	7751	7748	7751	7749	7749	7751
18	7747	7746	7747	7748	7747	7747	7747	7751	7746	7751	7748	7751	7749	7749	7748
19	7746	7747	7747	7748	7747	7746	7747	7749	7748	7751	7748	7748	7749	7749	7748
20	7746	7746	7747	7752	7750	7746	7747	7749	7746	7747	7748	7751	7749	7748	7748
21	7746	7747	7747	7748	7747	7746	7747	7749	7746	7751	7748	7751	7749	7750	7750
22	7746	7746	7748	7752	7747	7747	7747	7749	7748	7751	7748	7749	7749	7749	7748
23	7746	7746	7746	7748	7747	7746	7746	7749	7748	7751	7748	7751	7749	7749	7748
25	7746	7746	7746	7747	7747	7746	7748	7749	7748	7748	7748	7749	7750	7749	7749
30	7747	7747	7748	7752	7747	7747	7749	7749	7751	7751	7748	7749	7750	7749	7750
40	7748	7747	7747	7748	7747	7747	7748	7749	7749	7747	7751	7751	7750	7749	7748

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	7748 bytes	–	100%
1,000	7747 bytes	-1 byte	100%
10,000	7747 bytes	–	100%
100,000	7746 bytes	-1 byte	35.94%
1,000,000	7746 bytes	–	12.17%
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)	7749 bytes	+3 bytes (+0.04%)	–
1	7749 bytes	+3 bytes (+0.04%)	–
2	7778 bytes	+32 bytes (+0.41%)	+29 bytes
3	7805 bytes	+59 bytes (+0.76%)	+56 bytes
4	7834 bytes	+88 bytes (+1.14%)	+85 bytes
5	7861 bytes	+115 bytes (+1.48%)	+112 bytes
6	7870 bytes	+124 bytes (+1.60%)	+121 bytes
7	7908 bytes	+162 bytes (+2.09%)	+159 bytes
8	7936 bytes	+190 bytes (+2.45%)	+187 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	6715 bytes	-1031 bytes (-13.31%)
Brotli (Wikipedia)	brotli	brotli -q 11	7244 bytes	-502 bytes (-6.48%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	7302 bytes	-444 bytes (-5.73%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	7318 bytes	-428 bytes (-5.53%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	7621 bytes	-125 bytes (-1.61%)
Zstandard (Wikipedia)	zstd	zstd -19	7715 bytes	-31 bytes (-0.40%)
LZMA2 (Wikipedia)	xz	xz -9	7748 bytes	+2 bytes (+0.03%)

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.