Bootstrap 3.3.6 - as small as it gets (near-perfect GZIP compression)

Choose a version:

The original file has 68954 bytes (67.3k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 36868 bytes (36.0k, 53%).

After GZIP compression these minified files vary in size:

Microsoft	12955 bytes (12.7k)	CDN
Boot	11804 bytes (11.5k)	CDN
MaxCDN	11804 bytes (11.5k)	CDN
jsdelivr	11804 bytes (11.5k)	CDN
cdnjs	9856 bytes (9.6k)	CDN
gzip -6 (default)	9787 bytes (9.6k)	local copy
unpkg	9763 bytes (9.5k)	CDN
gzip -9	9762 bytes (9.5k)	local copy
Yandex	9743 bytes (9.5k)	CDN
libdeflate -12	9459 bytes (9.2k)	local copy
7zip -mx=9 -tgzip	9457 bytes (9.2k)	local copy
kzip -s0 -rn -b0	9455 bytes (9.2k)	local copy
zultra	9423 bytes (9.2k)	local copy
pigz -11 -n	9402 bytes (9.2k)	local copy
Zopfli	9395 bytes (9.2k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.3.6.min.js (or via HTTPS)

You will automatically get the smallest Bootstrap 3.3.6 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 348 bytes by using my Bootstrap 3.3.6 Zopfli version instead of the best available CDN (3.70% smaller than Yandex, 9395 vs. 9743 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 --i1000000 --mb8 --mls512 --bsr7 --lazy --ohh

(found November 26, 2015)

Description	Value	Parameter
iterations	1000000	--i1000000
maximum blocks	8	--mb8
maximum length score	512	--mls512
block splitting recursion	7	--bsr7
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/v3.3.6/dist/js/bootstrap.min.js --location | md5sum
c5b5b2fa19bd66ff23211d9f844e0131 -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.3.6.min.zopfli.js.gz | md5sum
c5b5b2fa19bd66ff23211d9f844e0131 -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/twbs/bootstrap/v3.3.6/dist/js/bootstrap.min.js --location | sha1sum
791aa054a026bddc0de92bad6cf7a1c6e73713d5 -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.3.6.min.zopfli.js.gz | sha1sum
791aa054a026bddc0de92bad6cf7a1c6e73713d5 -

All listed CDNs deliver identical contents:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Microsoft	12955 bytes	c5b5b2fa19bd66ff23211d9f844e0131	December 12, 2015 @ 20:47
Boot	11804 bytes	c5b5b2fa19bd66ff23211d9f844e0131	December 4, 2015 @ 08:32
MaxCDN	11804 bytes	c5b5b2fa19bd66ff23211d9f844e0131	(invalid)
jsdelivr	11804 bytes	c5b5b2fa19bd66ff23211d9f844e0131	November 29, 2015 @ 21:26
cdnjs	9856 bytes	c5b5b2fa19bd66ff23211d9f844e0131	(invalid)
unpkg	9763 bytes	c5b5b2fa19bd66ff23211d9f844e0131	July 11, 2016 @ 16:21
Yandex	9743 bytes	c5b5b2fa19bd66ff23211d9f844e0131	(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
9395 bytes	-1 byte	zopfli --i1000000 --mls512 --bsr7 --lazy --ohh	November 26, 2015 @ 12:37
9396 bytes	-1 byte	zopfli --i1000 --mls1024 --bsr19 --lazy --ohh	November 25, 2015 @ 11:44
9397 bytes	-1 byte	zopfli --i1000 --mls16384 --bsr8 --lazy --ohh	November 25, 2015 @ 11:32
9398 bytes	–	zopfli --i100 --mls16384 --bsr12 --lazy --ohh	November 25, 2015 @ 11:26

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:
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	9406	9406	9406	9406	9406	9405	9406	9407	9411	9413	9413	9400	9403	9406	9406
4	9397	9397	9396	9396	9396	9395	9397	9396	9397	9396	9400	9406	9399	9399	9403
6	9398	9398	9398	9400	9398	9397	9396	9396	9396	9397	9398	9399	9398	9396	9396
7	9397	9397	9403	9397	9403	9399	9395	9396	9395	9396	9399	9399	9401	9399	9406
8	9397	9397	9396	9397	9397	9397	9395	9396	9399	9401	9397	9399	9399	9396	9396
9	9398	9398	9397	9397	9397	9400	9400	9396	9395	9396	9396	9399	9399	9398	9399
10	9397	9397	9397	9397	9400	9399	9397	9396	9395	9396	9396	9400	9399	9399	9399
11	9397	9397	9396	9397	9396	9396	9396	9396	9396	9396	9396	9399	9399	9397	9405
12	9401	9401	9397	9397	9396	9396	9395	9396	9396	9396	9396	9400	9399	9396	9399
13	9397	9397	9396	9400	9397	9399	9395	9397	9399	9396	9396	9399	9399	9396	9396
14	9397	9397	9397	9396	9400	9397	9397	9396	9397	9396	9396	9399	9399	9395	9399
15	9397	9397	9396	9397	9396	9399	9396	9396	9396	9397	9399	9398	9399	9398	9399
16	9396	9396	9396	9396	9396	9397	9396	9396	9396	9401	9397	9398	9399	9395	9399
17	9396	9396	9397	9396	9396	9397	9397	9396	9396	9396	9396	9399	9399	9395	9399
18	9397	9397	9397	9396	9397	9399	9395	9396	9396	9396	9396	9399	9399	9395	9399
19	9396	9396	9397	9396	9397	9397	9395	9396	9396	9396	9397	9398	9399	9396	9399
20	9396	9396	9397	9396	9397	9396	9396	9396	9396	9396	9396	9398	9399	9396	9399
21	9396	9396	9397	9397	9396	9399	9395	9396	9395	9396	9396	9398	9399	9396	9399
22	9397	9397	9397	9396	9396	9397	9396	9396	9396	9396	9396	9399	9399	9396	9396
23	9397	9397	9396	9396	9397	9396	9395	9396	9398	9396	9396	9399	9399	9396	9399
25	9397	9397	9396	9397	9397	9397	9395	9396	9396	9396	9396	9399	9399	9396	9399
30	9397	9397	9397	9396	9396	9397	9396	9396	9396	9396	9396	9399	9399	9396	9399
40	9397	9397	9397	9396	9397	9396	9395	9396	9398	9396	9398	9398	9399	9396	9399

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	9398 bytes	–	100%
1,000	9396 bytes	-2 bytes	100%
10,000	9396 bytes	–	100%
100,000	9395 bytes	-1 byte	100%
1,000,000	9395 bytes	–	9.28%
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)	9455 bytes	+60 bytes (+0.64%)	–
1	9455 bytes	+60 bytes (+0.64%)	–
2	9459 bytes	+64 bytes (+0.68%)	+4 bytes
3	9479 bytes	+84 bytes (+0.89%)	+24 bytes
4	9486 bytes	+91 bytes (+0.97%)	+31 bytes
5	9528 bytes	+133 bytes (+1.42%)	+73 bytes
6	9576 bytes	+181 bytes (+1.93%)	+121 bytes
7	9609 bytes	+214 bytes (+2.28%)	+154 bytes
8	9651 bytes	+256 bytes (+2.72%)	+196 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	7827 bytes	-1568 bytes (-16.69%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	8493 bytes	-902 bytes (-9.60%)
Brotli (Wikipedia)	brotli	brotli -q 11	8647 bytes	-748 bytes (-7.96%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	8877 bytes	-518 bytes (-5.51%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	9132 bytes	-263 bytes (-2.80%)
LZMA2 (Wikipedia)	xz	xz -9	9344 bytes	-51 bytes (-0.54%)
Zstandard (Wikipedia)	zstd	zstd -19	9404 bytes	+9 bytes (+0.10%)

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.