React 15.4.2 - as small as it gets (near-perfect GZIP compression)

Choose a version:

The original file has 127694 bytes (124.7k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 21203 bytes (20.7k, 17%).

After GZIP compression these minified files vary in size:

Boot	8163 bytes (8.0k)	CDN
cdnjs	7326 bytes (7.2k)	CDN
gzip -6 (default)	7325 bytes (7.2k)	local copy
gzip -9	7306 bytes (7.1k)	local copy
unpkg	7305 bytes (7.1k)	CDN
jsdelivr	7303 bytes (7.1k)	CDN
libdeflate -12	7121 bytes (7.0k)	local copy
zultra	7116 bytes (6.9k)	local copy
7zip -mx=9 -tgzip	7076 bytes (6.9k)	local copy
pigz -11 -n	7035 bytes (6.9k)	local copy
kzip -s0 -rn -b3	7024 bytes (6.9k)	local copy
Zopfli	7002 bytes (6.8k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/react/react-15.4.2.min.js (or via HTTPS)

You will automatically get the smallest React 15.4.2 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 301 bytes by using my React 15.4.2 Zopfli version instead of the best available CDN (4.30% smaller than jsdelivr, 7002 vs. 7303 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 --mls4 --bsr25 --lazy --ohh

(found January 9, 2017)

Description	Value	Parameter
iterations	100000	--i100000
maximum blocks	8	--mb8
maximum length score	4	--mls4
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://fb.me/react-15.4.2.min.js --location | md5sum
fe3e04b0a969e3722ae34c9a06ef8f32 -
curl --silent --compressed https://minime.stephan-brumme.com/files/react/react-15.4.2.min.zopfli.js.gz | md5sum
fe3e04b0a969e3722ae34c9a06ef8f32 -

SHA1:
curl --silent --compressed https://fb.me/react-15.4.2.min.js --location | sha1sum
b71145e063c22556d375e065e02ea2ac66fd606a -
curl --silent --compressed https://minime.stephan-brumme.com/files/react/react-15.4.2.min.zopfli.js.gz | sha1sum
b71145e063c22556d375e065e02ea2ac66fd606a -

All listed CDNs deliver identical contents:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Boot	8163 bytes	fe3e04b0a969e3722ae34c9a06ef8f32	January 10, 2017 @ 05:20
cdnjs	7326 bytes	fe3e04b0a969e3722ae34c9a06ef8f32	(invalid)
unpkg	7305 bytes	fe3e04b0a969e3722ae34c9a06ef8f32	January 9, 2017 @ 14:46
jsdelivr	7303 bytes	fe3e04b0a969e3722ae34c9a06ef8f32	(invalid)

Note: only the MD5 hashes are shown to keep things simple.

Other Versions

Available React versions at minime.stephan-brumme.com:

18.2.0,
18.1.0, 18.0.0,
17.0.2, 17.0.1, 17.0.0,
16.14.0,
16.13.1, 16.13.0,
16.12.0,
16.11.0,
16.10.2, 16.10.1, 16.10.0,
16.9.0,
16.8.6, 16.8.5, 16.8.4, 16.8.3, 16.8.2, 16.8.1, 16.8.0,
16.7.0,
16.6.3, 16.6.1, 16.6.0,
16.5.2, 16.5.1, 16.5.0,
16.4.2, 16.4.1, 16.4.0,
16.3.2, 16.3.1, 16.3.0,
16.2.0,
16.1.1, 16.1.0, 16.0.0,
15.6.2, 15.6.1, 15.6.0,
15.5.2, 15.5.1, 15.5.0,
15.4.2, 15.4.1, 15.4.0,
15.3.2, 15.3.1, 15.3.0,
15.2.1, 15.2.0,
15.1.0,
15.0.2, 15.0.1, 15.0.0,
0.14.8, 0.14.7, 0.14.6, 0.14.5, 0.14.4, 0.14.3, 0.14.2, 0.14.1, 0.14.0,
0.13.3, 0.13.2, 0.13.1, 0.13.0,
0.12.2, 0.12.1, 0.12.0,
0.11.2, 0.11.1, 0.11.0,
0.10.0

The project site contains an overview how well these versions were compressed.
Other interesting projects are AngularJS, BackboneJS, Bootstrap, D3, Dojo, Ember, jQuery, Knockout, lodash, Socket.IO, ThreeJS, UnderscoreJS and Vue.

Changelog

Best Zopfli parameters so far:

Size	Improvement	Parameters	Found
7002 bytes	-2 bytes	zopfli --i100000 --mls4 --bsr25 --lazy --ohh	January 9, 2017 @ 15:31
7004 bytes	-1 byte	zopfli --i1000 --mls32 --bsr16 --lazy --ohh	January 9, 2017 @ 14:55
7005 bytes	-1 byte	zopfli --i1000 --mls16 --bsr9 --lazy --ohh	January 9, 2017 @ 14:55
7006 bytes	–	zopfli --i100 --mls32 --bsr10 --lazy --ohh	January 9, 2017 @ 14:47

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 @ 12:49.

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	7035	7035	7054	7051	7029	7030	7030	7038	7040	7039	7108	7106	7109	7085	7087
4	7029	7030	7043	7035	7038	7042	7044	7046	7026	7037	7029	7015	7104	7046	7022
6	7013	7012	7021	7017	7003	7013	7014	7013	7012	7016	7012	7013	7106	7017	7023
7	7007	7015	7008	7006	7023	7026	7003	7007	7046	7024	7110	7013	7018	7056	7027
8	7049	7034	7029	7025	7009	7028	7028	7029	7025	7024	7025	7015	7104	7015	7022
9	7013	7014	7010	7003	7006	7007	7006	7003	7003	7026	7108	7018	7018	7017	7017
10	7039	7034	7010	7026	7003	7015	7028	7010	7101	7015	7025	7023	7025	7056	7024
11	7011	7010	7012	7007	7003	7015	7003	7006	7029	7049	7007	7013	7104	7016	7026
12	7012	7102	7007	7025	7026	7014	7009	7011	7103	7024	7110	7016	7018	7047	7029
13	7014	7010	7005	7009	7003	7008	7003	7007	7006	7007	7006	7030	7033	7057	7025
14	7012	7014	7010	7005	7006	7007	7006	7003	7006	7027	7110	7029	7103	7053	7013
15	7052	7027	7007	7007	7006	7006	7003	7007	7024	7006	7007	7018	7103	7052	7026
16	7015	7009	7005	7003	7003	7012	7006	7012	7025	7026	7103	7015	7104	7025	7013
17	7036	7027	7005	7006	7003	7005	7003	7007	7025	7027	7022	7016	7029	7053	7053
18	7015	7007	7005	7006	7006	7006	7006	7003	7006	7004	7009	7013	7029	7059	7026
19	7015	7006	7008	7003	7003	7006	7003	7006	7003	7026	7022	7019	7104	7045	7026
20	7007	7010	7008	7006	7003	7005	7006	7014	7003	7006	7022	7016	7103	7052	7022
21	7015	7008	7008	7006	7003	7005	7006	7003	7024	7027	7110	7028	7027	7052	7024
22	7012	7009	7008	7008	7009	7011	7006	7003	7003	7006	7008	7023	7034	7017	7026
23	7007	7015	7009	7007	7007	7008	7006	7007	7009	7006	7009	7009	7018	7017	7026
25	7006	7002	7007	7007	7003	7004	7007	7005	7003	7009	7104	7013	7017	7033	7059
30	7007	7017	7006	7008	7007	7007	7003	7003	7006	7007	7006	7010	7104	7045	7034
40	7012	7010	7008	7006	7005	7006	7006	7030	7048	7026	7108	7013	7103	7012	7027

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	7006 bytes	–	100%
1,000	7004 bytes	-2 bytes	100%
10,000	7004 bytes	–	100%
100,000	7002 bytes	-2 bytes	9.86%
1,000,000	7002 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)	7115 bytes	+113 bytes (+1.61%)	+91 bytes
1	7115 bytes	+113 bytes (+1.61%)	+91 bytes
2	7109 bytes	+107 bytes (+1.53%)	+85 bytes
3	7024 bytes	+22 bytes (+0.31%)	–
4	7043 bytes	+41 bytes (+0.59%)	+19 bytes
5	7079 bytes	+77 bytes (+1.10%)	+55 bytes
6	7109 bytes	+107 bytes (+1.53%)	+85 bytes
7	7142 bytes	+140 bytes (+2.00%)	+118 bytes
8	7167 bytes	+165 bytes (+2.36%)	+143 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	6400 bytes	-602 bytes (-8.60%)
Brotli (Wikipedia)	brotli	brotli -q 11	6493 bytes	-509 bytes (-7.27%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	6851 bytes	-151 bytes (-2.16%)
LZMA2 (Wikipedia)	xz	xz -9	6916 bytes	-86 bytes (-1.23%)
Zstandard (Wikipedia)	zstd	zstd -19	7045 bytes	+43 bytes (+0.61%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	7080 bytes	+78 bytes (+1.11%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	7196 bytes	+194 bytes (+2.77%)

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 2025.
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.