React 16.13.1 - as small as it gets (near-perfect GZIP compression)

Choose a version:

The original file has 105138 bytes (102.7k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 12463 bytes (12.2k, 12%).

After GZIP compression these minified files vary in size:

gzip -6 (default)	4919 bytes (4.8k)	local copy
gzip -9	4917 bytes (4.8k)	local copy
Boot	4904 bytes (4.8k)	CDN
cdnjs	4904 bytes (4.8k)	CDN
zultra	4819 bytes (4.7k)	local copy
kzip -s0 -rn -b0	4817 bytes (4.7k)	local copy
libdeflate -12	4817 bytes (4.7k)	local copy
7zip -mx=9 -tgzip	4816 bytes (4.7k)	local copy
pigz -11 -n	4816 bytes (4.7k)	local copy
Zopfli	4811 bytes (4.7k)	local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/react/react-16.13.1.min.js (or via HTTPS)

You will automatically get the smallest React 16.13.1 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 93 bytes by using my React 16.13.1 Zopfli version instead of the best available CDN (1.93% smaller than cdnjs, 4811 vs. 4904 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 --bsr6 --lazy --ohh

(found March 20, 2020)

Description	Value	Parameter
iterations	100000	--i100000
maximum blocks	8	--mb8
maximum length score	32	--mls32
block splitting recursion	6	--bsr6
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-16.13.1.min.js --location | md5sum
edf56a42bca6b565bf7dfcbd8ffc221a -
curl --silent --compressed https://minime.stephan-brumme.com/files/react/react-16.13.1.min.zopfli.js.gz | md5sum
edf56a42bca6b565bf7dfcbd8ffc221a -

SHA1:
curl --silent --compressed https://fb.me/react-16.13.1.min.js --location | sha1sum
31cb4cea0064ed80c1b0c5f5d58e1956a7e2293f -
curl --silent --compressed https://minime.stephan-brumme.com/files/react/react-16.13.1.min.zopfli.js.gz | sha1sum
31cb4cea0064ed80c1b0c5f5d58e1956a7e2293f -

All listed CDNs deliver identical contents:

CDN	Size (compressed)	MD5 (uncompressed)	Timestamp
Boot	4904 bytes	edf56a42bca6b565bf7dfcbd8ffc221a	March 19, 2020 @ 21:15
cdnjs	4904 bytes	edf56a42bca6b565bf7dfcbd8ffc221a	March 19, 2020 @ 21:15

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
4811 bytes	-1 byte	zopfli --i100000 --mls32 --bsr6 --lazy --ohh	March 20, 2020 @ 11:11
4812 bytes	-1 byte	zopfli --i1000 --mls32 --bsr6 --lazy --ohh	March 20, 2020 @ 10:19
4813 bytes	–	zopfli --i100 --mls4096 --bsr14 --lazy --ohh	March 20, 2020 @ 10:16

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	4815	4815	4815	4815	4814	4814	4815	4815	4815	4814	4814	4814	4813	4813	4813
4	4813	4813	4814	4814	4812	4813	4812	4813	4814	4814	4814	4814	4814	4816	4816
6	4812	4812	4813	4812	4811	4814	4813	4814	4814	4814	4814	4814	4811	4814	4814
7	4813	4813	4813	4813	4815	4811	4813	4813	4811	4814	4814	4814	4811	4812	4812
8	4812	4812	4813	4812	4815	4812	4814	4814	4815	4814	4814	4814	4812	4812	4812
9	4812	4812	4815	4813	4813	4811	4815	4814	4812	4814	4814	4814	4813	4814	4814
10	4813	4813	4813	4811	4815	4813	4814	4813	4812	4814	4814	4811	4811	4811	4811
11	4813	4813	4812	4811	4811	4811	4812	4813	4815	4814	4814	4812	4811	4814	4814
12	4813	4813	4813	4814	4815	4814	4812	4814	4814	4814	4814	4811	4814	4812	4812
13	4813	4813	4813	4812	4814	4813	4813	4813	4814	4814	4814	4811	4813	4814	4814
14	4814	4814	4813	4813	4811	4812	4813	4815	4814	4814	4814	4811	4812	4815	4815
15	4813	4813	4814	4813	4813	4811	4812	4814	4812	4814	4814	4814	4811	4812	4812
16	4812	4812	4813	4814	4813	4812	4814	4814	4813	4814	4814	4814	4811	4812	4812
17	4812	4812	4813	4811	4815	4813	4812	4814	4813	4814	4814	4814	4814	4812	4812
18	4813	4813	4814	4818	4813	4812	4813	4814	4814	4814	4814	4811	4811	4812	4812
19	4811	4811	4813	4811	4813	4812	4812	4813	4814	4814	4814	4813	4811	4813	4813
20	4812	4812	4815	4813	4811	4811	4812	4814	4813	4814	4814	4814	4811	4814	4814
21	4813	4813	4815	4812	4811	4812	4812	4814	4812	4814	4814	4811	4811	4812	4812
22	4812	4812	4813	4811	4815	4814	4812	4814	4812	4814	4814	4814	4813	4811	4811
23	4812	4812	4812	4811	4811	4812	4812	4814	4813	4814	4814	4814	4811	4812	4812
25	4813	4813	4813	4812	4815	4811	4813	4815	4814	4814	4814	4814	4814	4813	4813
30	4812	4812	4812	4813	4814	4812	4813	4813	4811	4814	4814	4814	4812	4814	4814
40	4813	4813	4813	4813	4814	4813	4811	4813	4811	4814	4814	4812	4811	4814	4814

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	4813 bytes	–	100%
1,000	4812 bytes	-1 byte	100%
10,000	4812 bytes	–	100%
100,000	4811 bytes	-1 byte	34.49%
1,000,000	4811 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)	4817 bytes	+6 bytes (+0.12%)	–
1	4817 bytes	+6 bytes (+0.12%)	–
2	4824 bytes	+13 bytes (+0.27%)	+7 bytes
3	4861 bytes	+50 bytes (+1.04%)	+44 bytes
4	4884 bytes	+73 bytes (+1.52%)	+67 bytes
5	4902 bytes	+91 bytes (+1.89%)	+85 bytes
6	4930 bytes	+119 bytes (+2.47%)	+113 bytes
7	4960 bytes	+149 bytes (+3.10%)	+143 bytes
8	4998 bytes	+187 bytes (+3.89%)	+181 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
Brotli (Wikipedia)	brotli	brotli -q 11	4337 bytes	-474 bytes (-9.85%)
RAR (proprietary)	RAR	rar a -m5 -md64m -mc63:128t -mt1	4416 bytes	-395 bytes (-8.21%)
Zstandard (Wikipedia)	zstd	zstd -19	4813 bytes	+2 bytes (+0.04%)
LZMA2 (Wikipedia)	xz	xz -9	4840 bytes	+29 bytes (+0.60%)
PPMd (Wikipedia)	7zip	7za a -mx=9 -m0=ppmd	4911 bytes	+100 bytes (+2.08%)
Burrows-Wheeler transform (Wikipedia)	bzip2	bzip2 -9	4937 bytes	+126 bytes (+2.62%)
ZPAQ (Wikipedia)	zpaq	zpaq -method 69	5175 bytes	+364 bytes (+7.57%)

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.