Bootstrap 4.1.2 - as small as it gets (near-perfect GZIP compression)

Choose a version:

The original file has 123765 bytes (120.9k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 51039 bytes (49.8k, 41%).

After GZIP compression these minified files vary in size:

Boot	14199 bytes (13.9k)	CDN
cdnjs	14199 bytes (13.9k)	CDN
gzip -6 (default)	14113 bytes (13.8k)	local copy
MaxCDN	14090 bytes (13.8k)	CDN
jsdelivr	14090 bytes (13.8k)	CDN
gzip -9	14061 bytes (13.7k)	local copy
unpkg	14028 bytes (13.7k)	CDN
libdeflate -12	13609 bytes (13.3k)	local copy
7zip -mx=9 -tgzip	13605 bytes (13.3k)	local copy
zultra	13574 bytes (13.3k)	local copy
pigz -11 -n	13530 bytes (13.2k)	local copy
kzip -s0 -rn -b3	13529 bytes (13.2k)	local copy
Zopfli	13496 bytes (13.2k)	local copy
Zopfli (defluff)	13495 bytes (13.2k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/bootstrap/bootstrap-4.1.2.min.js (or via HTTPS)

You will automatically get the smallest Bootstrap 4.1.2 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 532 bytes by using my Bootstrap 4.1.2 Zopfli version instead of the best available CDN (3.94% smaller than unpkg, 13496 vs. 14028 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 --mls32 --bsr17 --lazy --ohh

(found July 13, 2018)

Description	Value	Parameter
iterations	100000	--i100000
maximum blocks	8	--mb8
maximum length score	32	--mls32
block splitting recursion	17	--bsr17
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

Even Smaller Files Thanks To Defluff

Zopfli's output can be further optimized by the defluff tool.
In this particular case, defluff saves 1 more byte (13495 bytes).

Download

Verify file integrity

After decompression, my uncompressed files are identical to the original ones:

MD5:
curl --silent --compressed https://raw.githubusercontent.com/twbs/bootstrap/v4.1.2/dist/js/bootstrap.min.js --location | md5sum
f92a3f337500984fbd20487501257dae -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-4.1.2.min.zopfli.js.gz | md5sum
f92a3f337500984fbd20487501257dae -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/twbs/bootstrap/v4.1.2/dist/js/bootstrap.min.js --location | sha1sum
6188ea651648c61ff3107c9d9a2b03a896972955 -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-4.1.2.min.zopfli.js.gz | sha1sum
6188ea651648c61ff3107c9d9a2b03a896972955 -

All listed CDNs deliver identical contents:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Boot	14199 bytes	f92a3f337500984fbd20487501257dae	(invalid)
cdnjs	14199 bytes	f92a3f337500984fbd20487501257dae	(invalid)
MaxCDN	14090 bytes	f92a3f337500984fbd20487501257dae	(invalid)
jsdelivr	14090 bytes	f92a3f337500984fbd20487501257dae	December 1, 2019 @ 05:24
unpkg	14028 bytes	f92a3f337500984fbd20487501257dae	(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
13496 bytes	-1 byte	zopfli --i100000 --mls32 --bsr17 --lazy --ohh	July 13, 2018 @ 18:00
13497 bytes	-1 byte	zopfli --i100000 --mls32 --bsr14 --lazy --ohh	July 13, 2018 @ 16:54
13498 bytes	-1 byte	zopfli --i10000 --mls32 --bsr30 --lazy --ohh	July 13, 2018 @ 16:29
13499 bytes	-1 byte	zopfli --i1000 --mls32 --bsr10 --lazy --ohh	July 13, 2018 @ 16:27
13500 bytes	-1 byte	zopfli --i1000 --mls32 --bsr14 --lazy --ohh	July 13, 2018 @ 16:26
13501 bytes	-1 byte	zopfli --i1000 --mls16 --bsr9 --lazy --ohh	July 13, 2018 @ 16:26
13502 bytes	-1 byte	zopfli --i1000 --mls4 --bsr8 --lazy --ohh	July 13, 2018 @ 16:26
13503 bytes	-1 byte	zopfli --i1000 --mls4 --bsr11 --lazy --ohh	July 13, 2018 @ 16:25
13504 bytes	–	zopfli --i100 --mls2 --bsr10 --lazy --ohh	July 13, 2018 @ 16:23

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	13562	13562	13521	13561	13519	13535	13535	13520	13528	13542	13541	13529	13551	13524	13544
4	13550	13551	13522	13503	13522	13522	13519	13512	13500	13515	13558	13553	13523	13532	13532
6	13501	13502	13512	13500	13500	13521	13512	13511	13497	13528	13516	13515	13538	13525	13514
7	13501	13501	13521	13503	13503	13512	13508	13510	13511	13511	13510	13526	13546	13515	13515
8	13500	13500	13522	13508	13510	13523	13510	13511	13520	13522	13511	13557	13558	13528	13528
9	13510	13510	13513	13498	13500	13522	13510	13516	13509	13521	13529	13551	13513	13513	13519
10	13498	13501	13521	13497	13498	13520	13510	13511	13510	13521	13511	13553	13544	13515	13516
11	13498	13501	13522	13511	13510	13521	13510	13510	13514	13521	13519	13511	13541	13511	13512
12	13510	13510	13523	13503	13510	13512	13510	13501	13509	13521	13511	13532	13532	13533	13516
13	13512	13503	13522	13511	13512	13522	13510	13511	13512	13521	13511	13557	13547	13527	13511
14	13510	13510	13525	13509	13497	13510	13507	13514	13515	13521	13550	13558	13540	13527	13528
15	13500	13500	13522	13503	13497	13521	13507	13510	13515	13510	13510	13520	13560	13531	13534
16	13510	13510	13521	13510	13510	13521	13510	13513	13513	13521	13511	13529	13540	13515	13513
17	13502	13502	13512	13503	13496	13509	13499	13500	13500	13512	13519	13511	13538	13529	13518
18	13501	13501	13521	13510	13510	13521	13510	13501	13500	13510	13509	13554	13543	13529	13530
19	13508	13508	13521	13509	13510	13521	13511	13511	13512	13521	13511	13554	13536	13515	13515
20	13501	13501	13514	13503	13497	13509	13520	13501	13498	13512	13510	13558	13540	13514	13514
21	13510	13510	13522	13509	13510	13522	13511	13500	13509	13520	13510	13510	13536	13515	13515
22	13503	13502	13522	13511	13512	13521	13514	13512	13513	13522	13510	13514	13542	13530	13530
23	13500	13500	13517	13498	13501	13522	13510	13512	13500	13510	13520	13519	13545	13540	13529
25	13510	13510	13522	13515	13514	13510	13510	13503	13500	13512	13511	13558	13543	13514	13514
30	13501	13501	13513	13502	13497	13511	13510	13511	13512	13521	13552	13554	13528	13527	13514
40	13500	13500	13522	13500	13509	13522	13510	13510	13510	13520	13510	13535	13541	13532	13530

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	13504 bytes	–	100%
1,000	13499 bytes	-5 bytes	100%
10,000	13498 bytes	-1 byte	100%
100,000	13496 bytes	-2 bytes	4.06%
1,000,000	13496 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)	13633 bytes	+137 bytes (+1.02%)	+104 bytes
1	13634 bytes	+138 bytes (+1.02%)	+105 bytes
2	13571 bytes	+75 bytes (+0.56%)	+42 bytes
3	13529 bytes	+33 bytes (+0.24%)	–
4	13542 bytes	+46 bytes (+0.34%)	+13 bytes
5	13560 bytes	+64 bytes (+0.47%)	+31 bytes
6	13598 bytes	+102 bytes (+0.76%)	+69 bytes
7	13623 bytes	+127 bytes (+0.94%)	+94 bytes
8	13663 bytes	+167 bytes (+1.24%)	+134 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	11438 bytes	-2058 bytes (-15.25%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	11691 bytes	-1805 bytes (-13.37%)
Brotli (Wikipedia)	brotli	brotli -q 11	12242 bytes	-1254 bytes (-9.29%)
LZMA2 (Wikipedia)	xz	xz -9	13076 bytes	-420 bytes (-3.11%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	13252 bytes	-244 bytes (-1.81%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	13267 bytes	-229 bytes (-1.70%)
Zstandard (Wikipedia)	zstd	zstd -19	13300 bytes	-196 bytes (-1.45%)

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 2024.
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.