Bootstrap 3.0.1 - as small as it gets (near-perfect GZIP compression)

Choose a version:

The original file has 58411 bytes (57.0k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 27832 bytes (27.2k, 48%).

After GZIP compression these minified files vary in size:

Microsoft	9512 bytes (9.3k)	CDN
Boot	8692 bytes (8.5k)	CDN
MaxCDN	8692 bytes (8.5k)	CDN
cdnjs	7358 bytes (7.2k)	CDN
gzip -6 (default)	7335 bytes (7.2k)	local copy
gzip -9	7317 bytes (7.1k)	local copy
Yandex	7301 bytes (7.1k)	CDN
jsdelivr	7301 bytes (7.1k)	CDN
7zip -mx=9 -tgzip	7079 bytes (6.9k)	local copy
libdeflate -12	7076 bytes (6.9k)	local copy
kzip -s0 -rn -b2	7063 bytes (6.9k)	local copy
zultra	7051 bytes (6.9k)	local copy
pigz -11 -n	7026 bytes (6.9k)	local copy
Zopfli	7021 bytes (6.9k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.0.1.min.js (or via HTTPS)

You will automatically get the smallest Bootstrap 3.0.1 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 280 bytes by using my Bootstrap 3.0.1 Zopfli version instead of the best available CDN (3.99% smaller than jsdelivr, 7021 vs. 7301 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 --i10000 --mb8 --mls512 --bsr9 --lazy --ohh

(found September 10, 2015)

Description	Value	Parameter
iterations	10000	--i10000
maximum blocks	8	--mb8
maximum length score	512	--mls512
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/v3.0.1/dist/js/bootstrap.min.js --location | md5sum
d6834e94301cc3ab9cc013574d092b61 -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.0.1.min.zopfli.js.gz | md5sum
d6834e94301cc3ab9cc013574d092b61 -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/twbs/bootstrap/v3.0.1/dist/js/bootstrap.min.js --location | sha1sum
0656f0d8f62bc0bbc2a745e0dc4dcc4213db4ed8 -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.0.1.min.zopfli.js.gz | sha1sum
0656f0d8f62bc0bbc2a745e0dc4dcc4213db4ed8 -

All listed CDNs deliver identical contents:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Microsoft	9512 bytes	d6834e94301cc3ab9cc013574d092b61	(invalid)
Boot	8692 bytes	d6834e94301cc3ab9cc013574d092b61	(invalid)
MaxCDN	8692 bytes	d6834e94301cc3ab9cc013574d092b61	(invalid)
cdnjs	7358 bytes	d6834e94301cc3ab9cc013574d092b61	(invalid)
Yandex	7301 bytes	d6834e94301cc3ab9cc013574d092b61	(invalid)
jsdelivr	7301 bytes	d6834e94301cc3ab9cc013574d092b61	(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
7021 bytes	-2 bytes	zopfli --i10000 --mls512 --bsr9 --lazy --ohh	September 10, 2015 @ 19:47
7023 bytes	-1 byte	zopfli --i1000 --mls512 --bsr11 --lazy --ohh	September 10, 2015 @ 16:53
7024 bytes	–	zopfli --i100 --mls512 --bsr16 --lazy --ohh	September 10, 2015 @ 16:28

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 @ 12:56.

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	7031	7031	7038	7031	7031	7031	7031	7031	7027	7026	7029	7024	7024	7025	7025
4	7037	7037	7036	7031	7027	7027	7023	7026	7028	7028	7027	7025	7027	7025	7025
6	7027	7027	7028	7027	7027	7029	7030	7025	7024	7029	7029	7024	7026	7023	7029
7	7027	7027	7027	7032	7027	7031	7028	7026	7021	7027	7026	7025	7025	7025	7026
8	7031	7031	7027	7031	7027	7026	7030	7025	7021	7024	7030	7024	7024	7025	7026
9	7031	7031	7031	7032	7031	7026	7028	7025	7021	7028	7027	7024	7025	7025	7025
10	7031	7031	7031	7031	7027	7028	7028	7026	7027	7023	7026	7027	7026	7025	7027
11	7030	7030	7027	7026	7027	7027	7027	7025	7023	7026	7029	7024	7026	7024	7025
12	7035	7035	7027	7026	7027	7027	7026	7025	7021	7026	7029	7026	7026	7026	7026
13	7035	7035	7035	7031	7031	7028	7027	7025	7027	7024	7029	7027	7026	7024	7025
14	7028	7028	7026	7026	7028	7027	7028	7025	7025	7027	7029	7027	7025	7024	7025
15	7036	7036	7026	7031	7027	7031	7022	7026	7027	7023	7029	7024	7024	7026	7026
16	7029	7029	7029	7026	7027	7026	7028	7026	7023	7027	7027	7027	7026	7025	7025
17	7035	7035	7030	7027	7027	7027	7028	7026	7027	7024	7023	7024	7026	7024	7026
18	7035	7035	7027	7031	7031	7025	7027	7023	7031	7023	7026	7025	7025	7024	7027
19	7030	7030	7027	7026	7028	7027	7028	7026	7023	7023	7027	7027	7026	7025	7024
20	7031	7031	7030	7026	7027	7028	7027	7025	7030	7023	7029	7027	7026	7024	7026
21	7035	7035	7027	7024	7027	7027	7027	7025	7021	7024	7026	7027	7026	7025	7026
22	7031	7031	7027	7026	7027	7027	7027	7025	7024	7023	7027	7024	7026	7025	7026
23	7031	7031	7027	7026	7027	7027	7027	7025	7021	7026	7027	7024	7024	7026	7024
25	7031	7031	7026	7026	7027	7027	7027	7025	7027	7026	7026	7024	7026	7024	7027
30	7031	7031	7026	7026	7027	7028	7028	7025	7023	7023	7026	7027	7024	7024	7024
40	7030	7030	7031	7026	7027	7027	7028	7025	7021	7027	7029	7024	7026	7025	7024

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	7024 bytes	–	100%
1,000	7023 bytes	-1 byte	100%
10,000	7021 bytes	-2 bytes	100%
100,000	7021 bytes	–	2.32%
1,000,000	7021 bytes	–	2.03%
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)	7069 bytes	+48 bytes (+0.68%)	+6 bytes
1	7070 bytes	+49 bytes (+0.70%)	+7 bytes
2	7063 bytes	+42 bytes (+0.60%)	–
3	7088 bytes	+67 bytes (+0.95%)	+25 bytes
4	7119 bytes	+98 bytes (+1.40%)	+56 bytes
5	7166 bytes	+145 bytes (+2.07%)	+103 bytes
6	7208 bytes	+187 bytes (+2.66%)	+145 bytes
7	7241 bytes	+220 bytes (+3.13%)	+178 bytes
8	7275 bytes	+254 bytes (+3.62%)	+212 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	5890 bytes	-1131 bytes (-16.11%)
Brotli (Wikipedia)	brotli	brotli -q 11	6463 bytes	-558 bytes (-7.95%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	6657 bytes	-364 bytes (-5.18%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	6870 bytes	-151 bytes (-2.15%)
LZMA2 (Wikipedia)	xz	xz -9	7036 bytes	+15 bytes (+0.21%)
Zstandard (Wikipedia)	zstd	zstd -19	7036 bytes	+15 bytes (+0.21%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	7238 bytes	+217 bytes (+3.09%)

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.