Bootstrap 3.2.0 - as small as it gets (near-perfect GZIP compression)

Choose a version:

The original file has 60681 bytes (59.3k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 31819 bytes (31.1k, 52%).

After GZIP compression these minified files vary in size:

Microsoft	11046 bytes (10.8k)	CDN
Boot	10258 bytes (10.0k)	CDN
MaxCDN	10258 bytes (10.0k)	CDN
Baidu	8602 bytes (8.4k)	CDN
cdnjs	8597 bytes (8.4k)	CDN
gzip -6 (default)	8559 bytes (8.4k)	local copy
gzip -9	8530 bytes (8.3k)	local copy
unpkg	8525 bytes (8.3k)	CDN
Yandex	8512 bytes (8.3k)	CDN
jsdelivr	8512 bytes (8.3k)	CDN
libdeflate -12	8253 bytes (8.1k)	local copy
kzip -s0 -rn -b0	8244 bytes (8.1k)	local copy
7zip -mx=9 -tgzip	8241 bytes (8.0k)	local copy
zultra	8224 bytes (8.0k)	local copy
pigz -11 -n	8205 bytes (8.0k)	local copy
Zopfli	8197 bytes (8.0k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.2.0.min.js (or via HTTPS)

You will automatically get the smallest Bootstrap 3.2.0 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 315 bytes by using my Bootstrap 3.2.0 Zopfli version instead of the best available CDN (3.84% smaller than jsdelivr, 8197 vs. 8512 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 --i1000 --mb8 --mls1024 --bsr13 --lazy --ohh

(found September 10, 2015)

Description	Value	Parameter
iterations	1000	--i1000
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/v3.2.0/dist/js/bootstrap.min.js --location | md5sum
abda843684d022f3bc22bc83927fe05f -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.2.0.min.zopfli.js.gz | md5sum
abda843684d022f3bc22bc83927fe05f -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/twbs/bootstrap/v3.2.0/dist/js/bootstrap.min.js --location | sha1sum
26908395e7a9a4eab607d80aa50a81d65f3017cb -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.2.0.min.zopfli.js.gz | sha1sum
26908395e7a9a4eab607d80aa50a81d65f3017cb -

These CDNs send you the original file:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Microsoft	11046 bytes	abda843684d022f3bc22bc83927fe05f	(invalid)
Boot	10258 bytes	abda843684d022f3bc22bc83927fe05f	(invalid)
MaxCDN	10258 bytes	abda843684d022f3bc22bc83927fe05f	(invalid)
cdnjs	8597 bytes	abda843684d022f3bc22bc83927fe05f	(invalid)
unpkg	8525 bytes	abda843684d022f3bc22bc83927fe05f	July 11, 2016 @ 16:21
Yandex	8512 bytes	abda843684d022f3bc22bc83927fe05f	(invalid)
jsdelivr	8512 bytes	abda843684d022f3bc22bc83927fe05f	(invalid)

And some CDNs send you a different file:

CDN	Size (compressed)	MD5 (uncompressed)	Comment / Diff	Timestamp
Baidu	8602 bytes	987facf80adec365394402f2026b943d	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
8197 bytes	-1 byte	zopfli --i1000 --mls1024 --bsr13 --lazy --ohh	September 10, 2015 @ 16:48
8198 bytes	-1 byte	zopfli --i1000 --mls512 --bsr9 --lazy --ohh	September 10, 2015 @ 16:47
8199 bytes	-2 bytes	zopfli --i1000 --mls512 --bsr4 --lazy --ohh	September 10, 2015 @ 16:47
8201 bytes	–	zopfli --i100 --mls2048 --bsr6 --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 @ 12:53.

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	8207	8208	8201	8207	8199	8203	8200	8201	8198	8211	8203	8201	8202	8201	8200
4	8198	8198	8199	8198	8198	8202	8201	8198	8198	8198	8198	8202	8201	8218	8201
6	8198	8198	8203	8198	8198	8200	8201	8202	8198	8198	8199	8202	8199	8198	8200
7	8198	8198	8198	8198	8198	8202	8198	8198	8198	8198	8199	8201	8202	8221	8201
8	8198	8198	8198	8198	8198	8198	8198	8202	8198	8198	8198	8202	8202	8201	8201
9	8199	8198	8198	8198	8198	8202	8198	8198	8198	8198	8198	8202	8199	8201	8200
10	8198	8199	8202	8198	8198	8200	8198	8198	8199	8198	8198	8203	8201	8201	8215
11	8198	8198	8198	8198	8198	8201	8202	8198	8198	8198	8198	8201	8199	8198	8200
12	8198	8198	8198	8198	8198	8199	8202	8198	8198	8198	8198	8201	8199	8198	8200
13	8198	8198	8198	8198	8198	8199	8202	8202	8198	8197	8198	8202	8201	8201	8201
14	8197	8198	8198	8198	8198	8201	8202	8198	8198	8198	8198	8201	8200	8199	8200
15	8200	8199	8198	8198	8198	8202	8201	8199	8198	8198	8202	8201	8203	8220	8200
16	8198	8199	8198	8198	8198	8198	8198	8198	8198	8198	8202	8201	8199	8201	8200
17	8198	8198	8198	8198	8198	8202	8198	8198	8198	8198	8198	8201	8201	8200	8200
18	8198	8199	8198	8198	8198	8198	8198	8202	8198	8198	8198	8201	8201	8198	8200
19	8198	8199	8198	8198	8198	8202	8198	8198	8199	8198	8198	8201	8203	8198	8199
20	8198	8198	8198	8198	8198	8202	8202	8198	8199	8198	8202	8202	8199	8201	8217
21	8198	8198	8198	8198	8198	8201	8202	8202	8198	8198	8200	8202	8200	8198	8200
22	8198	8200	8201	8198	8198	8201	8202	8198	8198	8198	8198	8201	8199	8201	8201
23	8198	8198	8198	8198	8198	8201	8199	8198	8198	8198	8198	8201	8201	8197	8200
25	8198	8198	8201	8198	8198	8201	8202	8198	8198	8198	8198	8201	8200	8221	8216
30	8198	8199	8198	8198	8199	8201	8198	8198	8198	8198	8198	8200	8200	8200	8200
40	8198	8198	8198	8198	8198	8202	8198	8201	8198	8198	8198	8201	8201	8219	8200

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	8201 bytes	–	100%
1,000	8197 bytes	-4 bytes	100%
10,000	8197 bytes	–	100%
100,000	8197 bytes	–	2.61%
1,000,000	8197 bytes	–	0.87%
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)	8244 bytes	+47 bytes (+0.57%)	–
1	8245 bytes	+48 bytes (+0.59%)	+1 byte
2	8247 bytes	+50 bytes (+0.61%)	+3 bytes
3	8256 bytes	+59 bytes (+0.72%)	+12 bytes
4	8289 bytes	+92 bytes (+1.12%)	+45 bytes
5	8329 bytes	+132 bytes (+1.61%)	+85 bytes
6	8369 bytes	+172 bytes (+2.10%)	+125 bytes
7	8399 bytes	+202 bytes (+2.46%)	+155 bytes
8	8434 bytes	+237 bytes (+2.89%)	+190 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	6875 bytes	-1322 bytes (-16.13%)
Brotli (Wikipedia)	brotli	brotli -q 11	7540 bytes	-657 bytes (-8.02%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	7638 bytes	-559 bytes (-6.82%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	7989 bytes	-208 bytes (-2.54%)
LZMA2 (Wikipedia)	xz	xz -9	8176 bytes	-21 bytes (-0.26%)
Zstandard (Wikipedia)	zstd	zstd -19	8215 bytes	+18 bytes (+0.22%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	8395 bytes	+198 bytes (+2.42%)

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.