Bootstrap 3.3.2 - as small as it gets (near-perfect GZIP compression)

Choose a version:

The original file has 66732 bytes (65.2k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 35452 bytes (34.6k, 53%).

After GZIP compression these minified files vary in size:

Microsoft	12247 bytes (12.0k)	CDN
Boot	11290 bytes (11.0k)	CDN
MaxCDN	11290 bytes (11.0k)	CDN
cdnjs	9490 bytes (9.3k)	CDN
gzip -6 (default)	9430 bytes (9.2k)	local copy
gzip -9	9399 bytes (9.2k)	local copy
unpkg	9392 bytes (9.2k)	CDN
jsdelivr	9379 bytes (9.2k)	CDN
kzip -s0 -rn -b1	9088 bytes (8.9k)	local copy
7zip -mx=9 -tgzip	9087 bytes (8.9k)	local copy
libdeflate -12	9087 bytes (8.9k)	local copy
zultra	9057 bytes (8.8k)	local copy
pigz -11 -n	9035 bytes (8.8k)	local copy
Zopfli	9025 bytes (8.8k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.3.2.min.js (or via HTTPS)

You will automatically get the smallest Bootstrap 3.3.2 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 354 bytes by using my Bootstrap 3.3.2 Zopfli version instead of the best available CDN (3.92% smaller than jsdelivr, 9025 vs. 9379 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 --mls256 --bsr25 --lazy --ohh

(found February 26, 2016)

Description	Value	Parameter
iterations	1000000	--i1000000
maximum blocks	8	--mb8
maximum length score	256	--mls256
block splitting recursion	25	--bsr25
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/v3.3.2/dist/js/bootstrap.min.js --location | md5sum
046ba2b5f4cff7d2eaaa1af55caa9fd8 -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.3.2.min.zopfli.js.gz | md5sum
046ba2b5f4cff7d2eaaa1af55caa9fd8 -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/twbs/bootstrap/v3.3.2/dist/js/bootstrap.min.js --location | sha1sum
b3f2ef9f985e7906c9360756b73cd64bf7733647 -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.3.2.min.zopfli.js.gz | sha1sum
b3f2ef9f985e7906c9360756b73cd64bf7733647 -

All listed CDNs deliver identical contents:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Microsoft	12247 bytes	046ba2b5f4cff7d2eaaa1af55caa9fd8	(invalid)
Boot	11290 bytes	046ba2b5f4cff7d2eaaa1af55caa9fd8	(invalid)
MaxCDN	11290 bytes	046ba2b5f4cff7d2eaaa1af55caa9fd8	(invalid)
cdnjs	9490 bytes	046ba2b5f4cff7d2eaaa1af55caa9fd8	(invalid)
unpkg	9392 bytes	046ba2b5f4cff7d2eaaa1af55caa9fd8	July 11, 2016 @ 16:21
jsdelivr	9379 bytes	046ba2b5f4cff7d2eaaa1af55caa9fd8	(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
9025 bytes	-1 byte	zopfli --i1000000 --mls256 --bsr25 --lazy --ohh	February 26, 2016 @ 16:36
9026 bytes	-1 byte	zopfli --i10000 --mls256 --bsr8 --lazy --ohh	September 17, 2015 @ 22:10
9027 bytes	-1 byte	zopfli --i10000 --mls512 --bsr4 --lazy --ohh	September 10, 2015 @ 17:29
9028 bytes	-1 byte	zopfli --i10000 --mls512 --bsr6 --lazy --ohh	September 10, 2015 @ 17:24
9029 bytes	-1 byte	zopfli --i1000 --mls512 --bsr13 --lazy --ohh	September 10, 2015 @ 16:35
9030 bytes	–	zopfli --i100 --mls1024 --bsr6 --lazy --ohh	September 10, 2015 @ 16:29

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 @ 12:52.

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 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	9037	9037	9037	9037	9038	9038	9039	9038	9037	9039	9040	9039	9037	9030	9038
4	9027	9027	9027	9028	9029	9031	9029	9027	9027	9029	9029	9037	9035	9029	9036
6	9028	9028	9029	9028	9031	9031	9027	9027	9028	9028	9031	9028	9029	9027	9029
7	9027	9027	9027	9028	9029	9029	9029	9028	9029	9029	9031	9031	9029	9029	9030
8	9025	9025	9028	9028	9029	9029	9028	9025	9030	9029	9031	9031	9029	9032	9029
9	9028	9028	9028	9029	9028	9029	9029	9030	9029	9030	9032	9032	9030	9029	9029
10	9025	9025	9028	9031	9029	9029	9029	9029	9030	9029	9033	9028	9029	9028	9030
11	9025	9025	9028	9031	9030	9031	9030	9025	9029	9029	9031	9031	9029	9029	9030
12	9028	9028	9031	9028	9031	9029	9029	9028	9029	9029	9029	9031	9029	9027	9030
13	9028	9028	9028	9028	9029	9029	9029	9025	9029	9029	9029	9028	9029	9036	9031
14	9028	9028	9029	9031	9030	9029	9029	9029	9029	9029	9031	9029	9029	9028	9030
15	9029	9029	9028	9027	9029	9029	9029	9028	9029	9029	9029	9036	9029	9029	9030
16	9028	9028	9028	9027	9029	9029	9030	9029	9029	9029	9031	9030	9029	9029	9030
17	9027	9027	9028	9031	9029	9029	9029	9025	9029	9030	9031	9030	9029	9028	9030
18	9028	9028	9029	9031	9029	9029	9029	9028	9027	9030	9031	9028	9029	9027	9028
19	9025	9025	9027	9028	9029	9029	9029	9028	9027	9030	9031	9029	9029	9029	9029
20	9025	9025	9029	9028	9029	9029	9029	9025	9027	9029	9031	9029	9029	9029	9029
21	9025	9025	9028	9028	9029	9029	9029	9025	9029	9029	9031	9028	9029	9029	9029
22	9025	9025	9029	9028	9029	9029	9029	9028	9029	9029	9029	9031	9029	9030	9030
23	9028	9028	9027	9028	9029	9029	9028	9028	9029	9029	9029	9031	9029	9027	9029
25	9028	9028	9028	9028	9029	9029	9029	9025	9029	9029	9033	9031	9030	9027	9029
30	9027	9027	9028	9027	9028	9030	9030	9028	9029	9029	9031	9029	9029	9028	9029
40	9028	9028	9029	9031	9029	9029	9029	9029	9029	9029	9029	9029	9029	9028	9029

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	9030 bytes	–	100%
1,000	9028 bytes	-2 bytes	100%
10,000	9026 bytes	-2 bytes	100%
100,000	9026 bytes	–	6.09%
1,000,000	9025 bytes	-1 byte	6.09%
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)	9089 bytes	+64 bytes (+0.71%)	+1 byte
1	9088 bytes	+63 bytes (+0.70%)	–
2	9091 bytes	+66 bytes (+0.73%)	+3 bytes
3	9093 bytes	+68 bytes (+0.75%)	+5 bytes
4	9125 bytes	+100 bytes (+1.11%)	+37 bytes
5	9166 bytes	+141 bytes (+1.56%)	+78 bytes
6	9209 bytes	+184 bytes (+2.04%)	+121 bytes
7	9241 bytes	+216 bytes (+2.39%)	+153 bytes
8	9283 bytes	+258 bytes (+2.86%)	+195 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	7511 bytes	-1514 bytes (-16.78%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	8211 bytes	-814 bytes (-9.02%)
Brotli (Wikipedia)	brotli	brotli -q 11	8320 bytes	-705 bytes (-7.81%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	8551 bytes	-474 bytes (-5.25%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	8751 bytes	-274 bytes (-3.04%)
LZMA2 (Wikipedia)	xz	xz -9	8996 bytes	-29 bytes (-0.32%)
Zstandard (Wikipedia)	zstd	zstd -19	9042 bytes	+17 bytes (+0.19%)

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.