BackboneJS 1.1.1 - as small as it gets (near-perfect GZIP compression)

The original file has 61015 bytes (59.6k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 20004 bytes (19.5k, 33%).

After GZIP compression these minified files vary in size:

Boot	7701 bytes (7.5k)	CDN
Baidu	6701 bytes (6.5k)	CDN
cdnjs	6696 bytes (6.5k)	CDN
gzip -6 (default)	6679 bytes (6.5k)	local copy
gzip -9	6674 bytes (6.5k)	local copy
unpkg	6669 bytes (6.5k)	CDN
Yandex	6652 bytes (6.5k)	CDN
7zip -mx=9 -tgzip	6502 bytes (6.3k)	local copy
libdeflate -12	6493 bytes (6.3k)	local copy
zultra	6493 bytes (6.3k)	local copy
pigz -11 -n	6490 bytes (6.3k)	local copy
kzip -s0 -rn -b1	6487 bytes (6.3k)	local copy
Zopfli	6483 bytes (6.3k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/backbonejs/backbone-1.1.1.min.js (or via HTTPS)

You will automatically get the smallest BackboneJS 1.1.1 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 169 bytes by using my BackboneJS 1.1.1 Zopfli version instead of the best available CDN (2.61% smaller than Yandex, 6483 vs. 6652 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 --mls4096 --bsr9 --lazy --ohh

(found November 18, 2015)

Description	Value	Parameter
iterations	100000	--i100000
maximum blocks	8	--mb8
maximum length score	4096	--mls4096
block splitting recursion	9	--bsr9
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/1.1.1/backbone-min.js --location | md5sum
54dea01fc5bfa946537fbad8c98b7505 -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.1.1.min.zopfli.js.gz | md5sum
54dea01fc5bfa946537fbad8c98b7505 -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/jashkenas/backbone/1.1.1/backbone-min.js --location | sha1sum
b7a1bd4fb9a9a7d8ec3b352d91104795c3924bdc -
curl --silent --compressed https://minime.stephan-brumme.com/files/backbonejs/backbone-1.1.1.min.zopfli.js.gz | sha1sum
b7a1bd4fb9a9a7d8ec3b352d91104795c3924bdc -

These CDNs send you the original file:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
unpkg	6669 bytes	54dea01fc5bfa946537fbad8c98b7505	July 11, 2016 @ 16:18

And some CDNs send you a different file:

CDN	Size (compressed)	MD5 (uncompressed)	Comment / Diff	Timestamp
Boot	7701 bytes	deb2fd0f79695f722f766c387751e286	only whitespaces differ	(invalid)
Baidu	6701 bytes	7bf5eefcb7f5b17a50a3b5be6b7e85c4	only whitespaces differ	(invalid)
cdnjs	6696 bytes	deb2fd0f79695f722f766c387751e286	only whitespaces differ	(invalid)
Yandex	6652 bytes	deb2fd0f79695f722f766c387751e286	only whitespaces differ	(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
6483 bytes	-1 byte	zopfli --i100000 --mls4096 --bsr9 --lazy --ohh	November 18, 2015 @ 04:58
6484 bytes	-2 bytes	zopfli --i1000 --mls4096 --bsr11 --lazy --ohh	September 8, 2015 @ 11:42
6486 bytes	-1 byte	zopfli --i1000 --mls512 --bsr4 --lazy --ohh	September 8, 2015 @ 11:42
6487 bytes	–	zopfli --i100 --mls4096 --bsr11 --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 @ 12:52.

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 or 100,000.

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	6489	6489	6489	6489	6489	6489	6489	6489	6489	6486	6490	6490	6488	6488	6488
4	6488	6491	6489	6490	6491	6489	6489	6487	6486	6486	6487	6485	6485	6484	6486
6	6489	6489	6487	6489	6489	6490	6489	6489	6488	6489	6488	6485	6486	6485	6485
7	6489	6487	6489	6489	6489	6489	6489	6487	6487	6486	6488	6485	6486	6483	6485
8	6489	6489	6490	6489	6489	6489	6489	6488	6487	6488	6489	6483	6486	6487	6483
9	6489	6491	6489	6489	6489	6489	6489	6487	6485	6487	6489	6483	6485	6485	6485
10	6489	6488	6487	6488	6489	6490	6489	6487	6487	6489	6488	6485	6486	6485	6485
11	6489	6488	6488	6489	6490	6489	6489	6487	6485	6486	6489	6483	6486	6489	6483
12	6489	6488	6487	6486	6489	6489	6489	6489	6489	6488	6488	6489	6486	6486	6486
13	6489	6488	6489	6489	6487	6489	6485	6489	6485	6486	6489	6483	6486	6485	6486
14	6489	6488	6489	6489	6489	6488	6490	6489	6486	6486	6488	6484	6485	6485	6485
15	6488	6489	6490	6489	6490	6488	6490	6487	6487	6490	6485	6490	6486	6486	6483
16	6489	6489	6490	6489	6489	6490	6489	6487	6486	6486	6485	6489	6486	6483	6486
17	6488	6488	6488	6489	6490	6490	6488	6489	6487	6485	6488	6484	6486	6485	6485
18	6489	6488	6487	6489	6490	6490	6488	6489	6487	6489	6488	6489	6483	6488	6486
19	6488	6488	6489	6489	6486	6488	6489	6489	6485	6484	6489	6483	6485	6485	6485
20	6489	6488	6488	6489	6489	6488	6483	6489	6485	6484	6488	6484	6485	6487	6486
21	6489	6489	6487	6489	6490	6490	6488	6489	6487	6489	6489	6485	6491	6483	6486
22	6490	6489	6489	6487	6489	6489	6485	6487	6487	6486	6488	6485	6486	6487	6486
23	6489	6488	6487	6486	6489	6489	6489	6489	6487	6489	6489	6483	6486	6487	6486
25	6489	6487	6487	6487	6489	6488	6489	6489	6487	6486	6488	6483	6486	6487	6486
30	6489	6490	6488	6485	6489	6490	6485	6487	6487	6486	6488	6489	6485	6485	6486
40	6488	6487	6489	6489	6490	6488	6489	6488	6485	6489	6488	6483	6485	6487	6486

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	6487 bytes	–	100%
1,000	6484 bytes	-3 bytes	100%
10,000	6484 bytes	–	100%
100,000	6483 bytes	-1 byte	6.38%
1,000,000	–	–	–
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)	6487 bytes	+4 bytes (+0.06%)	–
1	6487 bytes	+4 bytes (+0.06%)	–
2	6513 bytes	+30 bytes (+0.46%)	+26 bytes
3	6546 bytes	+63 bytes (+0.97%)	+59 bytes
4	6578 bytes	+95 bytes (+1.47%)	+91 bytes
5	6611 bytes	+128 bytes (+1.97%)	+124 bytes
6	6629 bytes	+146 bytes (+2.25%)	+142 bytes
7	6653 bytes	+170 bytes (+2.62%)	+166 bytes
8	6686 bytes	+203 bytes (+3.13%)	+199 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	5679 bytes	-804 bytes (-12.40%)
Brotli (Wikipedia)	brotli	brotli -q 11	6016 bytes	-467 bytes (-7.20%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	6087 bytes	-396 bytes (-6.11%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	6431 bytes	-52 bytes (-0.80%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	6445 bytes	-38 bytes (-0.59%)
Zstandard (Wikipedia)	zstd	zstd -19	6491 bytes	+8 bytes (+0.12%)
LZMA2 (Wikipedia)	xz	xz -9	6532 bytes	+49 bytes (+0.76%)

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.