Bootstrap 3.3.0 - as small as it gets (near-perfect GZIP compression)

Choose a version:

The original file has 65813 bytes (64.3k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 34653 bytes (33.8k, 53%).

After GZIP compression these minified files vary in size:

Microsoft	11996 bytes (11.7k)	CDN
Boot	11077 bytes (10.8k)	CDN
MaxCDN	11077 bytes (10.8k)	CDN
Baidu	9317 bytes (9.1k)	CDN
cdnjs	9311 bytes (9.1k)	CDN
gzip -6 (default)	9246 bytes (9.0k)	local copy
gzip -9	9216 bytes (9.0k)	local copy
unpkg	9213 bytes (9.0k)	CDN
Yandex	9196 bytes (9.0k)	CDN
jsdelivr	9196 bytes (9.0k)	CDN
libdeflate -12	8915 bytes (8.7k)	local copy
7zip -mx=9 -tgzip	8908 bytes (8.7k)	local copy
kzip -s0 -rn -b2	8901 bytes (8.7k)	local copy
zultra	8870 bytes (8.7k)	local copy
pigz -11 -n	8861 bytes (8.7k)	local copy
Zopfli	8855 bytes (8.6k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.3.0.min.js (or via HTTPS)

You will automatically get the smallest Bootstrap 3.3.0 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 341 bytes by using my Bootstrap 3.3.0 Zopfli version instead of the best available CDN (3.85% smaller than jsdelivr, 8855 vs. 9196 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 --bsr23 --lazy --ohh

(found December 1, 2015)

Description	Value	Parameter
iterations	100000	--i100000
maximum blocks	8	--mb8
maximum length score	4096	--mls4096
block splitting recursion	23	--bsr23
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/v3.3.0/dist/js/bootstrap.min.js --location | md5sum
281cd50dd9f58c5550620fc148a7bc39 -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.3.0.min.zopfli.js.gz | md5sum
281cd50dd9f58c5550620fc148a7bc39 -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/twbs/bootstrap/v3.3.0/dist/js/bootstrap.min.js --location | sha1sum
dfb8410ffc10a57d69b81620087c5a0b6027765a -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.3.0.min.zopfli.js.gz | sha1sum
dfb8410ffc10a57d69b81620087c5a0b6027765a -

These CDNs send you the original file:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Microsoft	11996 bytes	281cd50dd9f58c5550620fc148a7bc39	(invalid)
Boot	11077 bytes	281cd50dd9f58c5550620fc148a7bc39	(invalid)
MaxCDN	11077 bytes	281cd50dd9f58c5550620fc148a7bc39	(invalid)
cdnjs	9311 bytes	281cd50dd9f58c5550620fc148a7bc39	(invalid)
unpkg	9213 bytes	281cd50dd9f58c5550620fc148a7bc39	July 11, 2016 @ 16:21
Yandex	9196 bytes	281cd50dd9f58c5550620fc148a7bc39	(invalid)
jsdelivr	9196 bytes	281cd50dd9f58c5550620fc148a7bc39	(invalid)

And some CDNs send you a different file:

CDN	Size (compressed)	MD5 (uncompressed)	Comment / Diff	Timestamp
Baidu	9317 bytes	6a08a110509efe4a9b380f5a4f034915	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
8855 bytes	-1 byte	zopfli --i100000 --mls4096 --bsr23 --lazy --ohh	December 1, 2015 @ 13:19
8856 bytes	-1 byte	zopfli --i10000 --mls1024 --bsr8 --lazy --ohh	September 10, 2015 @ 17:52
8857 bytes	-1 byte	zopfli --i10000 --mls512 --bsr13 --lazy --ohh	September 10, 2015 @ 17:50
8858 bytes	-1 byte	zopfli --i1000 --mls512 --bsr4 --lazy --ohh	September 10, 2015 @ 16:37
8859 bytes	–	zopfli --i100 --mls4096 --bsr14 --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, 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	8857	8857	8858	8857	8867	8856	8858	8865	8863	8867	8861	8867	8858	8863	8863
4	8859	8859	8857	8858	8858	8858	8860	8858	8858	8857	8863	8861	8860	8861	8860
6	8858	8858	8858	8858	8858	8859	8858	8858	8858	8856	8858	8857	8860	8859	8863
7	8859	8859	8857	8859	8858	8866	8858	8858	8858	8858	8857	8857	8863	8861	8865
8	8858	8858	8857	8858	8858	8858	8860	8857	8857	8856	8858	8857	8860	8863	8862
9	8857	8857	8858	8858	8857	8860	8860	8859	8857	8857	8858	8860	8861	8863	8865
10	8857	8857	8857	8858	8858	8857	8860	8856	8857	8856	8858	8859	8860	8860	8860
11	8859	8859	8857	8857	8858	8858	8858	8858	8858	8856	8858	8857	8859	8858	8864
12	8859	8859	8857	8858	8858	8857	8857	8858	8859	8856	8858	8857	8860	8858	8861
13	8857	8857	8857	8858	8857	8858	8857	8858	8857	8857	8859	8857	8859	8863	8860
14	8857	8857	8857	8858	8857	8856	8858	8856	8858	8857	8857	8856	8861	8861	8863
15	8859	8859	8857	8858	8857	8858	8860	8856	8857	8856	8863	8861	8863	8863	8864
16	8856	8856	8858	8858	8858	8856	8860	8856	8857	8856	8857	8856	8860	8857	8861
17	8857	8857	8858	8858	8857	8858	8858	8858	8857	8857	8857	8857	8860	8861	8863
18	8858	8858	8858	8858	8858	8857	8860	8858	8858	8857	8857	8857	8859	8863	8863
19	8856	8856	8858	8857	8858	8858	8857	8858	8857	8856	8858	8857	8861	8863	8865
20	8859	8859	8857	8858	8857	8858	8858	8858	8858	8857	8857	8857	8860	8874	8864
21	8859	8859	8857	8857	8858	8858	8857	8858	8857	8856	8858	8858	8861	8863	8863
22	8859	8859	8857	8858	8858	8858	8861	8858	8857	8857	8858	8860	8863	8865	8865
23	8857	8857	8857	8859	8858	8858	8860	8857	8857	8857	8858	8855	8859	8858	8863
25	8859	8859	8857	8858	8858	8858	8857	8858	8857	8857	8858	8863	8860	8863	8863
30	8857	8857	8857	8857	8858	8857	8860	8858	8859	8857	8857	8857	8860	8858	8864
40	8858	8858	8857	8858	8858	8857	8860	8856	8857	8857	8858	8857	8860	8863	8863

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	8859 bytes	–	100%
1,000	8857 bytes	-2 bytes	100%
10,000	8856 bytes	-1 byte	100%
100,000	8855 bytes	-1 byte	6.96%
1,000,000	8855 bytes	–	0.29%
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)	8910 bytes	+55 bytes (+0.62%)	+9 bytes
1	8911 bytes	+56 bytes (+0.63%)	+10 bytes
2	8901 bytes	+46 bytes (+0.52%)	–
3	8914 bytes	+59 bytes (+0.67%)	+13 bytes
4	8948 bytes	+93 bytes (+1.05%)	+47 bytes
5	8988 bytes	+133 bytes (+1.50%)	+87 bytes
6	9032 bytes	+177 bytes (+2.00%)	+131 bytes
7	9066 bytes	+211 bytes (+2.38%)	+165 bytes
8	9109 bytes	+254 bytes (+2.87%)	+208 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	7386 bytes	-1469 bytes (-16.59%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	8087 bytes	-768 bytes (-8.67%)
Brotli (Wikipedia)	brotli	brotli -q 11	8153 bytes	-702 bytes (-7.93%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	8412 bytes	-443 bytes (-5.00%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	8593 bytes	-262 bytes (-2.96%)
LZMA2 (Wikipedia)	xz	xz -9	8824 bytes	-31 bytes (-0.35%)
Zstandard (Wikipedia)	zstd	zstd -19	8870 bytes	+15 bytes (+0.17%)

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.