BackboneJS 1.2.0 - as small as it gets (near-perfect GZIP compression)

The original file has 71024 bytes (69.4k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 22810 bytes (22.3k, 32%).

After GZIP compression these minified files vary in size:

Boot	8689 bytes (8.5k)	CDN
cdnjs	7522 bytes (7.3k)	CDN
gzip -6 (default)	7495 bytes (7.3k)	local copy
gzip -9	7486 bytes (7.3k)	local copy
unpkg	7480 bytes (7.3k)	CDN
jsdelivr	7468 bytes (7.3k)	CDN
7zip -mx=9 -tgzip	7259 bytes (7.1k)	local copy
zultra	7257 bytes (7.1k)	local copy
libdeflate -12	7250 bytes (7.1k)	local copy
pigz -11 -n	7250 bytes (7.1k)	local copy
kzip -s0 -rn -b1	7243 bytes (7.1k)	local copy
Zopfli	7242 bytes (7.1k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-1.2.0.min.js (or via HTTPS)

You will automatically get the smallest BackboneJS 1.2.0 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 226 bytes by using my BackboneJS 1.2.0 Zopfli version instead of the best available CDN (3.12% smaller than jsdelivr, 7242 vs. 7468 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 --mls128 --bsr14 --lazy --ohh

(found November 18, 2015)

Description	Value	Parameter
iterations	100000	--i100000
maximum blocks	8	--mb8
maximum length score	128	--mls128
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/1.2.0/backbone-min.js --location | md5sum
85f7529d40aa7690189d05a524c2828e -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.2.0.min.zopfli.js.gz | md5sum
85f7529d40aa7690189d05a524c2828e -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/1.2.0/backbone-min.js --location | sha1sum
d511a7a34dd62f15aa00fe13283ef90d7ac9cbfa -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.2.0.min.zopfli.js.gz | sha1sum
d511a7a34dd62f15aa00fe13283ef90d7ac9cbfa -

All listed CDNs deliver identical contents:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Boot	8689 bytes	85f7529d40aa7690189d05a524c2828e	(invalid)
cdnjs	7522 bytes	85f7529d40aa7690189d05a524c2828e	(invalid)
unpkg	7480 bytes	85f7529d40aa7690189d05a524c2828e	July 11, 2016 @ 16:18
jsdelivr	7468 bytes	85f7529d40aa7690189d05a524c2828e	(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
7242 bytes	-1 byte	zopfli --i100000 --mls128 --bsr14 --lazy --ohh	November 18, 2015 @ 07:38
7243 bytes	-1 byte	zopfli --i1000 --mls2048 --bsr13 --lazy --ohh	September 8, 2015 @ 11:40
7244 bytes	-1 byte	zopfli --i1000 --mls1024 --bsr4 --lazy --ohh	September 8, 2015 @ 11:40
7245 bytes	–	zopfli --i100 --mls2048 --bsr8 --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 @ 12:49.

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	7244	7249	7244	7245	7244	7246	7247	7246	7248	7245	7244	7244	7244	7245	7245
4	7252	7252	7252	7245	7250	7253	7244	7244	7249	7243	7245	7244	7244	7244	7244
6	7250	7247	7244	7248	7244	7249	7246	7251	7251	7244	7245	7242	7248	7244	7245
7	7244	7244	7248	7249	7244	7249	7244	7244	7251	7244	7246	7255	7247	7245	7246
8	7250	7244	7246	7248	7246	7246	7243	7246	7250	7244	7243	7244	7246	7245	7245
9	7248	7248	7250	7248	7251	7253	7246	7245	7250	7246	7244	7242	7244	7245	7244
10	7244	7245	7246	7249	7246	7249	7248	7252	7247	7246	7246	7242	7246	7244	7246
11	7250	7244	7250	7249	7251	7249	7244	7245	7243	7246	7245	7243	7247	7245	7246
12	7244	7244	7247	7244	7244	7248	7245	7251	7247	7243	7245	7242	7246	7244	7247
13	7244	7244	7251	7248	7250	7246	7245	7251	7251	7243	7243	7242	7244	7244	7245
14	7247	7247	7244	7249	7244	7253	7242	7244	7247	7243	7243	7244	7247	7245	7246
15	7244	7245	7243	7244	7246	7244	7244	7244	7251	7244	7246	7242	7247	7245	7245
16	7247	7245	7243	7248	7254	7248	7245	7251	7248	7244	7247	7242	7247	7245	7247
17	7250	7248	7248	7249	7248	7250	7242	7246	7251	7246	7246	7244	7246	7244	7246
18	7246	7244	7246	7249	7252	7247	7242	7251	7248	7245	7245	7242	7247	7245	7247
19	7244	7246	7246	7249	7250	7252	7244	7251	7248	7244	7244	7242	7246	7245	7246
20	7244	7244	7246	7248	7244	7249	7245	7244	7251	7244	7245	7242	7244	7245	7247
21	7248	7244	7246	7247	7244	7249	7245	7244	7244	7244	7245	7242	7247	7244	7246
22	7244	7245	7246	7248	7252	7248	7245	7251	7251	7244	7243	7242	7246	7245	7246
23	7248	7245	7249	7250	7250	7248	7245	7251	7248	7244	7246	7242	7247	7244	7246
25	7250	7247	7249	7248	7250	7248	7244	7251	7247	7244	7245	7242	7247	7245	7245
30	7250	7245	7247	7248	7244	7248	7244	7247	7251	7246	7246	7242	7246	7245	7244
40	7247	7245	7246	7247	7244	7249	7242	7247	7251	7245	7246	7244	7247	7245	7244

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	7245 bytes	–	100%
1,000	7243 bytes	-2 bytes	100%
10,000	7243 bytes	–	100%
100,000	7242 bytes	-1 byte	14.49%
1,000,000	7242 bytes	–	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)	7243 bytes	+1 byte (+0.01%)	–
1	7243 bytes	+1 byte (+0.01%)	–
2	7276 bytes	+34 bytes (+0.47%)	+33 bytes
3	7305 bytes	+63 bytes (+0.87%)	+62 bytes
4	7342 bytes	+100 bytes (+1.38%)	+99 bytes
5	7356 bytes	+114 bytes (+1.57%)	+113 bytes
6	7386 bytes	+144 bytes (+1.99%)	+143 bytes
7	7404 bytes	+162 bytes (+2.24%)	+161 bytes
8	7435 bytes	+193 bytes (+2.67%)	+192 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	6321 bytes	-921 bytes (-12.72%)
Brotli (Wikipedia)	brotli	brotli -q 11	6768 bytes	-474 bytes (-6.55%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	6803 bytes	-439 bytes (-6.06%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	6953 bytes	-289 bytes (-3.99%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	7135 bytes	-107 bytes (-1.48%)
Zstandard (Wikipedia)	zstd	zstd -19	7238 bytes	-4 bytes (-0.06%)
LZMA2 (Wikipedia)	xz	xz -9	7264 bytes	+22 bytes (+0.30%)

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.