Bootstrap 3.0.3 - as small as it gets (near-perfect GZIP compression)

Choose a version:

The original file has 58533 bytes (57.2k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 27822 bytes (27.2k, 48%).

After GZIP compression these minified files vary in size:

Microsoft	9494 bytes (9.3k)	CDN
Boot	8671 bytes (8.5k)	CDN
MaxCDN	8671 bytes (8.5k)	CDN
Baidu	7336 bytes (7.2k)	CDN
cdnjs	7329 bytes (7.2k)	CDN
gzip -6 (default)	7306 bytes (7.1k)	local copy
gzip -9	7288 bytes (7.1k)	local copy
Yandex	7273 bytes (7.1k)	CDN
jsdelivr	7273 bytes (7.1k)	CDN
libdeflate -12	7054 bytes (6.9k)	local copy
7zip -mx=9 -tgzip	7045 bytes (6.9k)	local copy
kzip -s0 -rn -b1	7038 bytes (6.9k)	local copy
zultra	7027 bytes (6.9k)	local copy
pigz -11 -n	7000 bytes (6.8k)	local copy
Zopfli	6994 bytes (6.8k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.0.3.min.js (or via HTTPS)

You will automatically get the smallest Bootstrap 3.0.3 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 279 bytes by using my Bootstrap 3.0.3 Zopfli version instead of the best available CDN (3.99% smaller than jsdelivr, 6994 vs. 7273 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 --mls1024 --bsr13 --lazy --ohh

(found November 23, 2015)

Description	Value	Parameter
iterations	100000	--i100000
maximum blocks	8	--mb8
maximum length score	1024	--mls1024
block splitting recursion	13	--bsr13
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/twbs/bootstrap/v3.0.3/dist/js/bootstrap.min.js --location | md5sum
353240ad37d1b084a53b1575f8ce57da -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.0.3.min.zopfli.js.gz | md5sum
353240ad37d1b084a53b1575f8ce57da -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/twbs/bootstrap/v3.0.3/dist/js/bootstrap.min.js --location | sha1sum
b3182f99be238cc41164df8615005fad53282b4e -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.0.3.min.zopfli.js.gz | sha1sum
b3182f99be238cc41164df8615005fad53282b4e -

These CDNs send you the original file:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Microsoft	9494 bytes	353240ad37d1b084a53b1575f8ce57da	(invalid)
Boot	8671 bytes	353240ad37d1b084a53b1575f8ce57da	(invalid)
MaxCDN	8671 bytes	353240ad37d1b084a53b1575f8ce57da	(invalid)
cdnjs	7329 bytes	353240ad37d1b084a53b1575f8ce57da	(invalid)
Yandex	7273 bytes	353240ad37d1b084a53b1575f8ce57da	(invalid)
jsdelivr	7273 bytes	353240ad37d1b084a53b1575f8ce57da	(invalid)

And some CDNs send you a different file:

CDN	Size (compressed)	MD5 (uncompressed)	Comment / Diff	Timestamp
Baidu	7336 bytes	ddf62d2a6b8d502890dca20f3eb20b81	only whitespaces differ	(invalid)

Note: only the MD5 hashes are shown to keep things simple.

Other Versions

Available Bootstrap versions at minime.stephan-brumme.com:

5.2.3, 5.2.2, 5.2.1, 5.2.0,
5.1.3, 5.1.2, 5.1.1, 5.1.0,
5.0.2, 5.0.1, 5.0.0,
4.6.0,
4.5.3, 4.5.2, 4.5.1, 4.5.0,
4.4.1, 4.4.0,
4.3.1, 4.3.0,
4.2.1, 4.2.0,
4.1.3, 4.1.2, 4.1.1, 4.1.0, 4.0.0,
3.4.1, 3.4.0,
3.3.7, 3.3.6, 3.3.5, 3.3.4, 3.3.2, 3.3.1, 3.3.0,
3.2.0,
3.1.1, 3.1.0,
3.0.3, 3.0.2, 3.0.1, 3.0.0

The project site contains an overview how well these versions were compressed.
Other interesting projects are AngularJS, BackboneJS, D3, Dojo, Ember, jQuery, Knockout, lodash, React, Socket.IO, ThreeJS, UnderscoreJS and Vue.

Changelog

Best Zopfli parameters so far:

Size	Improvement	Parameters	Found
6994 bytes	-1 byte	zopfli --i100000 --mls1024 --bsr13 --lazy --ohh	November 23, 2015 @ 15:33
6995 bytes	-1 byte	zopfli --i10000 --mls512 --bsr6 --lazy --ohh	September 10, 2015 @ 18:50
6996 bytes	-1 byte	zopfli --i1000 --mls512 --bsr10 --lazy --ohh	September 10, 2015 @ 16:51
6997 bytes	–	zopfli --i100 --mls512 --bsr16 --lazy --ohh	September 10, 2015 @ 16:27

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 @ 12:48.

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 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	7011	7011	7010	7011	7011	7010	7011	7013	6998	7001	7000	6999	7000	6999	6998
4	7010	7010	7010	7009	7001	7009	7009	7000	6994	7000	7001	7001	7000	7001	7002
6	7009	7009	7010	7011	7001	7006	7000	7000	6994	7002	6999	6996	7000	6998	6999
7	7010	7010	7011	7010	7000	7000	7009	7000	6997	7002	6996	6996	6999	6998	6999
8	7012	7012	7010	7011	7012	7010	7009	6999	6998	7002	6999	6998	7000	6996	6996
9	7010	7010	7010	7000	7000	7006	7009	6999	6997	6996	7004	6997	6998	6999	6996
10	7010	7010	7010	7000	7000	7000	7009	7000	6994	6996	7002	6996	6996	6998	6999
11	7011	7011	7010	7010	7010	7010	7009	6999	6997	7002	6994	6997	6999	6998	6999
12	7011	7011	7010	7010	7000	7010	6997	6999	6994	7002	6999	6998	6998	6998	6999
13	7000	7000	7010	7010	7011	7010	7000	6999	6994	6994	6999	6998	6996	6999	6999
14	7011	7011	7011	7001	7010	7010	7009	6999	7000	6994	6999	6999	6997	6996	6999
15	7011	7011	7011	7010	7000	6999	7009	7000	6996	7002	6999	6996	6999	6998	6999
16	7010	7010	7010	7009	7000	6999	7000	6999	6994	7002	6999	6999	6999	6999	6999
17	7011	7011	7010	7009	7010	7010	7000	6999	6994	6996	6999	6996	6997	6999	6999
18	7010	7010	7010	7010	7001	6999	7000	6999	6996	6996	6999	6996	6998	6999	7001
19	6997	6997	7010	7009	7000	7000	6997	6999	6994	6996	6999	6998	6998	6999	6999
20	7011	7011	7010	7009	7012	7010	7009	6999	6996	7002	6999	6999	6998	6998	6999
21	7010	7010	7000	7009	7000	7000	7009	6999	6996	7002	6999	6998	6997	6999	6999
22	7010	7010	7010	7000	7000	7000	6997	6996	6994	7002	6999	6996	6996	6998	6999
23	7011	7011	7010	7010	7009	7010	6997	7000	6994	7002	6999	6996	6998	6999	6999
25	7011	7011	7010	7010	7000	6999	7000	7000	6994	7002	6999	6998	6998	6996	6999
30	6997	6997	7001	7001	7010	7008	7009	6998	6997	6996	6999	6999	6996	6996	6996
40	7009	7009	7011	7010	7001	7000	6997	6999	7000	6996	6999	6999	6997	6998	6999

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	6997 bytes	–	100%
1,000	6996 bytes	-1 byte	100%
10,000	6995 bytes	-1 byte	100%
100,000	6994 bytes	-1 byte	4.06%
1,000,000	6994 bytes	–	4.06%
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)	7039 bytes	+45 bytes (+0.64%)	+1 byte
1	7038 bytes	+44 bytes (+0.63%)	–
2	7055 bytes	+61 bytes (+0.87%)	+17 bytes
3	7060 bytes	+66 bytes (+0.94%)	+22 bytes
4	7093 bytes	+99 bytes (+1.42%)	+55 bytes
5	7140 bytes	+146 bytes (+2.09%)	+102 bytes
6	7180 bytes	+186 bytes (+2.66%)	+142 bytes
7	7212 bytes	+218 bytes (+3.12%)	+174 bytes
8	7248 bytes	+254 bytes (+3.63%)	+210 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	5866 bytes	-1128 bytes (-16.13%)
Brotli (Wikipedia)	brotli	brotli -q 11	6456 bytes	-538 bytes (-7.69%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	6635 bytes	-359 bytes (-5.13%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	6834 bytes	-160 bytes (-2.29%)
Zstandard (Wikipedia)	zstd	zstd -19	7006 bytes	+12 bytes (+0.17%)
LZMA2 (Wikipedia)	xz	xz -9	7008 bytes	+14 bytes (+0.20%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	7211 bytes	+217 bytes (+3.10%)

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.