Choose a version:
10% The original file has 120472 bytes (117.6k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 12601 bytes (12.3k, 10%).

After GZIP compression these minified files vary in size:
gzip -6 (default)
  4976 bytes (4.9k)
local copy
gzip -9
  4975 bytes (4.9k)
local copy
Boot
  4959 bytes (4.8k)
CDN
cdnjs
  4959 bytes (4.8k)
CDN
jsdelivr
  4955 bytes (4.8k)
CDN
libdeflate -12
  4875 bytes (4.8k)
local copy
kzip -s0 -rn -b0
  4874 bytes (4.8k)
local copy
pigz -11 -n
  4872 bytes (4.8k)
local copy
7zip -mx=9 -tgzip
  4871 bytes (4.8k)
local copy
Zopfli
  4866 bytes (4.8k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/react/react-16.11.0.min.js (or via HTTPS)

You will automatically get the smallest React 16.11.0 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 89 bytes by using my React 16.11.0 Zopfli version instead of the best available CDN (1.83% smaller than jsdelivr, 4866 vs. 4955 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 --mls32 --bsr40 --lazy --ohh

(found October 23, 2019)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 32  --mls32
block splitting recursion 40  --bsr40
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-16.11.0.min.js --location | md5sum
8226265a1a2ebe4dce8c5f4ecade92c9  -
curl --silent --compressed https://minime.stephan-brumme.com/files/react/react-16.11.0.min.zopfli.js.gz | md5sum
8226265a1a2ebe4dce8c5f4ecade92c9  -

SHA1:
curl --silent --compressed https://fb.me/react-16.11.0.min.js --location | sha1sum
05e78f122d2bebe951e6e72ca1aa41d0629b2328  -
curl --silent --compressed https://minime.stephan-brumme.com/files/react/react-16.11.0.min.zopfli.js.gz | sha1sum
05e78f122d2bebe951e6e72ca1aa41d0629b2328  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 4959 bytes 8226265a1a2ebe4dce8c5f4ecade92c9 November 19, 2019 @ 21:03
cdnjs 4959 bytes 8226265a1a2ebe4dce8c5f4ecade92c9 November 19, 2019 @ 20:59
jsdelivr 4955 bytes 8226265a1a2ebe4dce8c5f4ecade92c9 October 23, 2019 @ 10:50

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

Other Versions

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

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
4866 bytes -1 byte zopfli --i100000 --mls32 --bsr40 --lazy --ohh October 23, 2019 @ 13:02
4867 bytes -1 byte zopfli --i10000 --mls2 --bsr4 --lazy --ohh October 23, 2019 @ 11:27
4868 bytes -1 byte zopfli --i1000 --mls32 --bsr8 --lazy --ohh October 23, 2019 @ 11:23
4869 bytes zopfli --i100 --mls4 --bsr4 --lazy --ohh October 23, 2019 @ 11:19

If there are multiple parameter sets yielding the same compressed size, only the first one found is shown.

Most recent activity on November 19, 2019 @ 21:03.

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
4871 4871 4870 4869 4870 4869 4869 4869 4869 4869 4869 4869 4868 4869 4869
4867 4867 4869 4871 4869 4869 4869 4869 4869 4869 4869 4869 4870 4868 4868
4870 4870 4871 4870 4866 4868 4868 4868 4869 4869 4869 4869 4868 4869 4869
4868 4868 4869 4869 4868 4869 4869 4870 4869 4869 4869 4869 4870 4870 4870
4870 4870 4870 4871 4868 4869 4869 4869 4869 4869 4869 4869 4872 4869 4869
4867 4867 4868 4871 4868 4868 4869 4869 4869 4869 4869 4871 4872 4869 4869
4871 4871 4871 4869 4868 4868 4870 4868 4869 4869 4869 4872 4870 4868 4868
4870 4870 4868 4868 4868 4869 4870 4869 4869 4869 4869 4872 4868 4870 4870
4870 4870 4870 4869 4868 4869 4869 4868 4869 4869 4869 4872 4868 4869 4869
4868 4868 4867 4870 4868 4868 4870 4869 4869 4869 4869 4872 4870 4872 4872
4871 4871 4868 4868 4868 4867 4870 4870 4869 4869 4869 4872 4870 4870 4870
4868 4868 4869 4870 4868 4867 4869 4870 4869 4869 4869 4871 4871 4869 4869
4868 4868 4868 4869 4868 4868 4869 4868 4869 4869 4869 4871 4868 4869 4869
4868 4868 4870 4868 4868 4868 4868 4868 4869 4869 4869 4872 4870 4870 4870
4869 4869 4868 4871 4868 4868 4870 4870 4869 4869 4869 4869 4870 4869 4869
4868 4868 4868 4869 4868 4868 4869 4869 4869 4869 4869 4872 4868 4870 4870
4868 4868 4867 4871 4868 4869 4869 4869 4869 4869 4869 4872 4870 4869 4869
4871 4871 4871 4871 4868 4868 4868 4868 4869 4869 4869 4871 4870 4870 4870
4869 4869 4867 4869 4868 4869 4869 4869 4869 4869 4869 4871 4870 4870 4870
4870 4870 4870 4869 4868 4869 4868 4868 4869 4869 4869 4872 4868 4870 4870
4869 4869 4871 4869 4868 4869 4870 4869 4869 4869 4869 4872 4870 4871 4871
4871 4871 4870 4871 4868 4869 4870 4870 4869 4869 4869 4871 4866 4870 4870
4872 4872 4869 4869 4866 4867 4870 4868 4869 4869 4869 4871 4868 4870 4870

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 4869 bytes 100%
1,000 4868 bytes -1 byte 100%
10,000 4867 bytes -1 byte 100%
100,000 4866 bytes -1 byte 3.77%
1,000,000 4866 bytes 0.87%
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
4874 bytes +8 bytes (+0.16%)
4874 bytes +8 bytes (+0.16%)
4888 bytes +22 bytes (+0.45%) +14 bytes
4909 bytes +43 bytes (+0.88%) +35 bytes
4922 bytes +56 bytes (+1.15%) +48 bytes
4953 bytes +87 bytes (+1.79%) +79 bytes
4984 bytes +118 bytes (+2.42%) +110 bytes
5016 bytes +150 bytes (+3.08%) +142 bytes
5058 bytes +192 bytes (+3.95%) +184 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 - but your browser doesn't support it.
Algorithm Program Parameters Size Compared To Best Zopfli
Brotli (Wikipedia) brotli brotli -q 11 4376 bytes -490 bytes (-10.07%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 4469 bytes -397 bytes (-8.16%)
Zstandard (Wikipedia) zstd zstd -19 4868 bytes +2 bytes (+0.04%)
LZMA2 (Wikipedia) xz xz -9 4904 bytes +38 bytes (+0.78%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 4972 bytes +106 bytes (+2.18%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 5009 bytes +143 bytes (+2.94%)
ZPAQ (Wikipedia) zpaq zpaq -method 69 5232 bytes +366 bytes (+7.52%)

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 2019.
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.