Bootstrap 3.0.0 - as small as it gets (near-perfect GZIP compression)

Choose a version:

The original file has 58458 bytes (57.1k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 27726 bytes (27.1k, 47%).

After GZIP compression these minified files vary in size:

Microsoft	9452 bytes (9.2k)	CDN
Boot	8632 bytes (8.4k)	CDN
MaxCDN	8632 bytes (8.4k)	CDN
cdnjs	7300 bytes (7.1k)	CDN
gzip -6 (default)	7275 bytes (7.1k)	local copy
gzip -9	7258 bytes (7.1k)	local copy
Sina	7252 bytes (7.1k)	CDN
Yandex	7242 bytes (7.1k)	CDN
jsdelivr	7242 bytes (7.1k)	CDN
7zip -mx=9 -tgzip	7018 bytes (6.9k)	local copy
libdeflate -12	7018 bytes (6.9k)	local copy
kzip -s0 -rn -b0	7010 bytes (6.8k)	local copy
zultra	6999 bytes (6.8k)	local copy
pigz -11 -n	6974 bytes (6.8k)	local copy
Zopfli	6967 bytes (6.8k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.0.0.min.js (or via HTTPS)

You will automatically get the smallest Bootstrap 3.0.0 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 275 bytes by using my Bootstrap 3.0.0 Zopfli version instead of the best available CDN (3.95% smaller than jsdelivr, 6967 vs. 7242 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 --mls2048 --bsr9 --lazy --ohh

(found December 1, 2015)

Description	Value	Parameter
iterations	100000	--i100000
maximum blocks	8	--mb8
maximum length score	2048	--mls2048
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/twbs/bootstrap/v3.0.0/dist/js/bootstrap.min.js --location | md5sum
9e25e8e29ef0ea358e9778082ffd97d8 -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.0.0.min.zopfli.js.gz | md5sum
9e25e8e29ef0ea358e9778082ffd97d8 -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/twbs/bootstrap/v3.0.0/dist/js/bootstrap.min.js --location | sha1sum
75a42212affc118fef849aba4b9326a7da2acda1 -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.0.0.min.zopfli.js.gz | sha1sum
75a42212affc118fef849aba4b9326a7da2acda1 -

All listed CDNs deliver identical contents:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Microsoft	9452 bytes	9e25e8e29ef0ea358e9778082ffd97d8	(invalid)
Boot	8632 bytes	9e25e8e29ef0ea358e9778082ffd97d8	(invalid)
MaxCDN	8632 bytes	9e25e8e29ef0ea358e9778082ffd97d8	(invalid)
cdnjs	7300 bytes	9e25e8e29ef0ea358e9778082ffd97d8	(invalid)
Sina	7252 bytes	9e25e8e29ef0ea358e9778082ffd97d8	(invalid)
Yandex	7242 bytes	9e25e8e29ef0ea358e9778082ffd97d8	(invalid)
jsdelivr	7242 bytes	9e25e8e29ef0ea358e9778082ffd97d8	(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
6967 bytes	-1 byte	zopfli --i100000 --mls2048 --bsr9 --lazy --ohh	December 1, 2015 @ 10:07
6968 bytes	-2 bytes	zopfli --i1000 --mls2048 --bsr14 --lazy --ohh	September 10, 2015 @ 16:55
6970 bytes	–	zopfli --i100 --mls512 --bsr16 --lazy --ohh	September 10, 2015 @ 16:29

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, 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	6982	6982	6982	6982	6982	6983	6983	6982	6976	6972	6973	6972	6972	6972	6972
4	6976	6976	6979	6971	6971	6970	6976	6971	6972	6972	6971	6974	6973	6973	6973
6	6976	6976	6970	6977	6975	6970	6975	6969	6971	6973	6978	6971	6971	6969	6971
7	6976	6976	6970	6974	6975	6970	6976	6971	6971	6970	6972	6971	6971	6971	6971
8	6970	6970	6970	6970	6975	6971	6976	6970	6975	6971	6970	6971	6969	6968	6971
9	6971	6971	6970	6970	6975	6970	6971	6971	6970	6971	6967	6971	6971	6971	6971
10	6970	6970	6970	6970	6971	6970	6976	6971	6972	6973	6972	6971	6971	6969	6972
11	6975	6975	6971	6971	6970	6970	6970	6970	6971	6969	6972	6970	6968	6969	6971
12	6970	6970	6970	6970	6971	6975	6970	6970	6970	6973	6972	6971	6969	6969	6971
13	6979	6979	6970	6970	6970	6970	6970	6971	6975	6973	6977	6971	6969	6974	6971
14	6970	6970	6971	6975	6974	6970	6970	6969	6971	6971	6968	6970	6969	6969	6971
15	6975	6975	6971	6970	6975	6970	6971	6971	6971	6973	6972	6972	6970	6971	6971
16	6970	6970	6976	6970	6971	6970	6971	6971	6968	6973	6972	6971	6969	6971	6971
17	6976	6976	6971	6971	6971	6972	6971	6970	6971	6968	6973	6971	6971	6968	6971
18	6971	6971	6970	6971	6970	6970	6971	6970	6975	6970	6971	6971	6971	6971	6971
19	6970	6970	6970	6970	6972	6970	6971	6971	6969	6969	6972	6971	6971	6971	6971
20	6971	6971	6970	6975	6972	6970	6975	6971	6976	6970	6974	6971	6971	6969	6971
21	6976	6976	6970	6970	6971	6970	6976	6971	6971	6973	6970	6972	6969	6968	6971
22	6976	6976	6970	6970	6975	6971	6970	6971	6975	6970	6972	6971	6969	6969	6971
23	6970	6970	6970	6970	6970	6970	6976	6971	6969	6970	6972	6971	6972	6971	6971
25	6970	6970	6970	6970	6971	6970	6970	6970	6971	6973	6972	6971	6969	6969	6971
30	6970	6970	6971	6971	6971	6971	6972	6971	6971	6970	6967	6970	6969	6968	6971
40	6970	6970	6971	6972	6972	6970	6972	6970	6971	6972	6972	6971	6968	6971	6971

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	6970 bytes	–	100%
1,000	6968 bytes	-2 bytes	100%
10,000	6968 bytes	–	100%
100,000	6967 bytes	-1 byte	3.19%
1,000,000	6967 bytes	–	0.58%
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)	7010 bytes	+43 bytes (+0.62%)	–
1	7010 bytes	+43 bytes (+0.62%)	–
2	7022 bytes	+55 bytes (+0.79%)	+12 bytes
3	7032 bytes	+65 bytes (+0.93%)	+22 bytes
4	7063 bytes	+96 bytes (+1.38%)	+53 bytes
5	7111 bytes	+144 bytes (+2.07%)	+101 bytes
6	7153 bytes	+186 bytes (+2.67%)	+143 bytes
7	7186 bytes	+219 bytes (+3.14%)	+176 bytes
8	7219 bytes	+252 bytes (+3.62%)	+209 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	5836 bytes	-1131 bytes (-16.23%)
Brotli (Wikipedia)	brotli	brotli -q 11	6428 bytes	-539 bytes (-7.74%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	6602 bytes	-365 bytes (-5.24%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	6812 bytes	-155 bytes (-2.22%)
Zstandard (Wikipedia)	zstd	zstd -19	6981 bytes	+14 bytes (+0.20%)
LZMA2 (Wikipedia)	xz	xz -9	6984 bytes	+17 bytes (+0.24%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	7192 bytes	+225 bytes (+3.23%)

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.