Bootstrap 3.1.1 - as small as it gets (near-perfect GZIP compression)

Choose a version:

The original file has 55258 bytes (54.0k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 29110 bytes (28.4k, 53%).

After GZIP compression these minified files vary in size:

Microsoft	9946 bytes (9.7k)	CDN
Boot	9167 bytes (9.0k)	CDN
MaxCDN	9167 bytes (9.0k)	CDN
Baidu	7736 bytes (7.6k)	CDN
cdnjs	7731 bytes (7.5k)	CDN
gzip -6 (default)	7702 bytes (7.5k)	local copy
gzip -9	7684 bytes (7.5k)	local copy
unpkg	7681 bytes (7.5k)	CDN
Yandex	7668 bytes (7.5k)	CDN
jsdelivr	7668 bytes (7.5k)	CDN
libdeflate -12	7434 bytes (7.3k)	local copy
7zip -mx=9 -tgzip	7423 bytes (7.2k)	local copy
kzip -s0 -rn -b1	7419 bytes (7.2k)	local copy
zultra	7414 bytes (7.2k)	local copy
pigz -11 -n	7384 bytes (7.2k)	local copy
Zopfli	7376 bytes (7.2k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.1.1.min.js (or via HTTPS)

You will automatically get the smallest Bootstrap 3.1.1 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 292 bytes by using my Bootstrap 3.1.1 Zopfli version instead of the best available CDN (3.96% smaller than jsdelivr, 7376 vs. 7668 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 --mls64 --bsr40 --lazy --ohh

(found February 26, 2016)

Description	Value	Parameter
iterations	1000000	--i1000000
maximum blocks	8	--mb8
maximum length score	64	--mls64
block splitting recursion	40	--bsr40
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/v3.1.1/dist/js/bootstrap.min.js --location | md5sum
ba847811448ef90d98d272aeccef2a95 -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.1.1.min.zopfli.js.gz | md5sum
ba847811448ef90d98d272aeccef2a95 -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/twbs/bootstrap/v3.1.1/dist/js/bootstrap.min.js --location | sha1sum
5814e91bb6276f4de8b7951c965f2f190a03978d -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.1.1.min.zopfli.js.gz | sha1sum
5814e91bb6276f4de8b7951c965f2f190a03978d -

These CDNs send you the original file:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Microsoft	9946 bytes	ba847811448ef90d98d272aeccef2a95	(invalid)
Boot	9167 bytes	ba847811448ef90d98d272aeccef2a95	(invalid)
MaxCDN	9167 bytes	ba847811448ef90d98d272aeccef2a95	(invalid)
cdnjs	7731 bytes	ba847811448ef90d98d272aeccef2a95	(invalid)
unpkg	7681 bytes	ba847811448ef90d98d272aeccef2a95	July 11, 2016 @ 16:21
Yandex	7668 bytes	ba847811448ef90d98d272aeccef2a95	(invalid)
jsdelivr	7668 bytes	ba847811448ef90d98d272aeccef2a95	(invalid)

And some CDNs send you a different file:

CDN	Size (compressed)	MD5 (uncompressed)	Comment / Diff	Timestamp
Baidu	7736 bytes	d1ea2970e53802116381cfd3f61a747a	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
7376 bytes	-1 byte	zopfli --i1000000 --mls64 --bsr40 --lazy --ohh	February 26, 2016 @ 14:45
7377 bytes	-1 byte	zopfli --i100000 --mls2 --bsr10 --lazy --ohh	November 18, 2015 @ 09:24
7378 bytes	-1 byte	zopfli --i1000 --mls2048 --bsr12 --lazy --ohh	September 10, 2015 @ 16:49
7379 bytes	-1 byte	zopfli --i1000 --mls1024 --bsr6 --lazy --ohh	September 10, 2015 @ 16:49
7380 bytes	–	zopfli --i100 --mls512 --bsr2 --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 @ 12:50.

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	7389	7389	7390	7390	7390	7380	7379	7384	7378	7384	7385	7384	7387	7385	7384
4	7387	7387	7384	7378	7381	7379	7379	7376	7380	7381	7380	7381	7383	7383	7384
6	7387	7387	7387	7379	7379	7380	7379	7379	7377	7379	7379	7380	7384	7384	7384
7	7387	7387	7383	7380	7380	7379	7379	7380	7377	7379	7379	7380	7378	7380	7383
8	7379	7379	7385	7376	7379	7379	7379	7380	7379	7379	7380	7377	7384	7383	7383
9	7379	7379	7383	7377	7379	7376	7379	7379	7377	7378	7379	7380	7383	7384	7384
10	7376	7376	7386	7377	7376	7379	7377	7381	7379	7379	7383	7377	7379	7379	7379
11	7387	7387	7384	7380	7381	7376	7379	7376	7377	7379	7381	7380	7380	7379	7384
12	7379	7379	7381	7379	7379	7378	7379	7376	7379	7379	7376	7377	7383	7379	7383
13	7387	7387	7384	7379	7379	7378	7379	7381	7379	7379	7378	7380	7384	7379	7384
14	7378	7378	7384	7379	7380	7379	7379	7380	7379	7380	7379	7381	7383	7379	7383
15	7379	7379	7385	7380	7379	7379	7379	7380	7379	7380	7379	7377	7380	7379	7383
16	7388	7388	7385	7379	7379	7379	7379	7379	7379	7380	7378	7381	7388	7383	7384
17	7388	7388	7385	7379	7384	7379	7380	7381	7379	7379	7379	7381	7380	7380	7379
18	7388	7388	7385	7379	7379	7379	7379	7381	7377	7380	7377	7379	7379	7378	7380
19	7379	7379	7384	7379	7379	7376	7379	7380	7380	7379	7379	7380	7383	7379	7383
20	7388	7388	7385	7376	7379	7376	7379	7380	7380	7380	7379	7381	7383	7384	7383
21	7378	7378	7385	7379	7379	7379	7379	7381	7377	7379	7380	7379	7384	7379	7384
22	7379	7379	7383	7378	7379	7379	7379	7380	7377	7380	7379	7379	7380	7380	7383
23	7386	7386	7384	7379	7379	7379	7379	7380	7377	7379	7379	7380	7380	7379	7379
25	7379	7379	7381	7379	7379	7376	7379	7381	7377	7379	7378	7377	7381	7383	7383
30	7379	7379	7384	7376	7379	7379	7379	7379	7379	7378	7380	7379	7383	7384	7384
40	7379	7379	7385	7379	7379	7376	7380	7380	7377	7379	7379	7379	7388	7383	7384

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	7379 bytes	–	100%
1,000	7378 bytes	-1 byte	100%
10,000	7378 bytes	–	100%
100,000	7377 bytes	-1 byte	14.78%
1,000,000	7376 bytes	-1 byte	10.14%
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)	7419 bytes	+43 bytes (+0.58%)	–
1	7419 bytes	+43 bytes (+0.58%)	–
2	7431 bytes	+55 bytes (+0.75%)	+12 bytes
3	7436 bytes	+60 bytes (+0.81%)	+17 bytes
4	7479 bytes	+103 bytes (+1.40%)	+60 bytes
5	7524 bytes	+148 bytes (+2.01%)	+105 bytes
6	7556 bytes	+180 bytes (+2.44%)	+137 bytes
7	7592 bytes	+216 bytes (+2.93%)	+173 bytes
8	7628 bytes	+252 bytes (+3.42%)	+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	6183 bytes	-1193 bytes (-16.17%)
Brotli (Wikipedia)	brotli	brotli -q 11	6815 bytes	-561 bytes (-7.61%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	6930 bytes	-446 bytes (-6.05%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	7204 bytes	-172 bytes (-2.33%)
LZMA2 (Wikipedia)	xz	xz -9	7388 bytes	+12 bytes (+0.16%)
Zstandard (Wikipedia)	zstd	zstd -19	7393 bytes	+17 bytes (+0.23%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	7583 bytes	+207 bytes (+2.81%)

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.