Choose a version:
12% 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
  4818 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-16.13.0.min.js (or via HTTPS)

You will automatically get the smallest React 16.13.0 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 16.13.0 Zopfli version instead of the best available CDN (1.93% smaller than cdnjs, 4811 vs. 4904 bytes):
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 --mls512 --bsr30 --lazy --ohh

(found February 28, 2020)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 512  --mls512
block splitting recursion 30  --bsr30
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-16.13.0.min.js --location | md5sum
0a82f766cc2d7330a971407e82c4e4a1  -
curl --silent --compressed https://minime.stephan-brumme.com/files/react/react-16.13.0.min.zopfli.js.gz | md5sum
0a82f766cc2d7330a971407e82c4e4a1  -

SHA1:
curl --silent --compressed https://fb.me/react-16.13.0.min.js --location | sha1sum
3dd41e46fe56aebfa6ccf0a5170738134d65e8ad  -
curl --silent --compressed https://minime.stephan-brumme.com/files/react/react-16.13.0.min.zopfli.js.gz | sha1sum
3dd41e46fe56aebfa6ccf0a5170738134d65e8ad  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 4904 bytes 0a82f766cc2d7330a971407e82c4e4a1 February 27, 2020 @ 11:46
cdnjs 4904 bytes 0a82f766cc2d7330a971407e82c4e4a1 February 27, 2020 @ 11:46

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

Other Versions

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

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 --mls512 --bsr30 --lazy --ohh February 28, 2020 @ 17:23
4812 bytes -1 byte zopfli --i1000 --mls32 --bsr6 --lazy --ohh February 28, 2020 @ 13:08
4813 bytes -1 byte zopfli --i1000 --mls2 --bsr8 --lazy --ohh February 28, 2020 @ 13:03
4814 bytes zopfli --i100 --mls8 --bsr11 --lazy --ohh February 28, 2020 @ 12:50

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
4815 4815 4815 4815 4814 4814 4815 4815 4815 4814 4814 4814 4813 4814 4814
4813 4813 4814 4814 4813 4813 4812 4813 4814 4814 4814 4814 4814 4816 4816
4812 4812 4813 4812 4811 4814 4813 4811 4814 4814 4814 4814 4811 4814 4814
4813 4813 4814 4813 4815 4815 4813 4814 4811 4814 4814 4814 4812 4812 4812
4812 4812 4813 4812 4815 4812 4814 4814 4811 4814 4814 4814 4813 4813 4813
4812 4812 4815 4813 4813 4811 4815 4814 4812 4814 4814 4814 4813 4814 4814
4813 4813 4813 4811 4815 4813 4814 4814 4812 4814 4814 4814 4811 4814 4814
4813 4813 4812 4812 4811 4813 4812 4814 4812 4814 4814 4814 4813 4814 4814
4813 4813 4814 4814 4815 4814 4815 4811 4814 4814 4814 4814 4813 4812 4812
4813 4813 4813 4812 4814 4813 4813 4814 4814 4814 4814 4814 4813 4814 4814
4814 4814 4813 4813 4811 4812 4813 4813 4814 4814 4814 4814 4814 4814 4814
4813 4813 4814 4813 4813 4813 4814 4814 4812 4814 4814 4814 4813 4813 4813
4812 4812 4814 4814 4813 4812 4814 4814 4813 4814 4814 4814 4811 4812 4812
4812 4812 4813 4811 4815 4813 4811 4814 4813 4814 4814 4814 4813 4812 4812
4813 4813 4814 4818 4813 4812 4813 4815 4814 4814 4814 4814 4811 4812 4812
4813 4813 4813 4811 4813 4812 4812 4815 4814 4814 4814 4814 4812 4814 4814
4812 4812 4815 4813 4811 4813 4812 4815 4812 4814 4814 4814 4813 4814 4814
4813 4813 4815 4812 4811 4812 4814 4814 4812 4814 4814 4814 4811 4812 4812
4812 4812 4814 4811 4815 4814 4812 4814 4812 4814 4814 4814 4813 4811 4811
4812 4812 4812 4811 4811 4812 4814 4814 4812 4814 4814 4814 4814 4813 4813
4813 4813 4814 4812 4815 4813 4813 4815 4814 4814 4814 4814 4813 4813 4813
4812 4812 4812 4813 4814 4812 4813 4814 4811 4814 4814 4814 4814 4814 4814
4813 4813 4813 4813 4814 4813 4813 4814 4811 4814 4814 4814 4813 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 4814 bytes 100%
1,000 4812 bytes -2 bytes 100%
10,000 4812 bytes 100%
100,000 4811 bytes -1 byte 25.51%
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
4818 bytes +7 bytes (+0.15%)
4818 bytes +7 bytes (+0.15%)
4823 bytes +12 bytes (+0.25%) +5 bytes
4861 bytes +50 bytes (+1.04%) +43 bytes
4884 bytes +73 bytes (+1.52%) +66 bytes
4901 bytes +90 bytes (+1.87%) +83 bytes
4928 bytes +117 bytes (+2.43%) +110 bytes
4960 bytes +149 bytes (+3.10%) +142 bytes
4997 bytes +186 bytes (+3.87%) +179 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 4336 bytes -475 bytes (-9.87%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 4415 bytes -396 bytes (-8.23%)
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 4912 bytes +101 bytes (+2.10%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 4939 bytes +128 bytes (+2.66%)
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):


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 2020.
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.