Choose a version:
48% The original file has 495159 bytes (483.6k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 236746 bytes (231.2k, 48%).

After GZIP compression these minified files vary in size:
cdnjs
  78638 bytes (76.8k)
CDN
gzip -6 (default)
  78094 bytes (76.3k)
local copy
gzip -9
  77834 bytes (76.0k)
local copy
libdeflate -12
  74595 bytes (72.8k)
local copy
7zip -mx=9 -tgzip
  74316 bytes (72.6k)
local copy
Zopfli
  73805 bytes (72.1k)
local copy
pigz -11 -n
  73802 bytes (72.1k)
local copy
kzip -s0 -rn -b8
  73772 bytes (72.0k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/d3/d3-5.5.0.min.js (or via HTTPS)

You will automatically get the smallest D3 5.5.0 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 4833 bytes by using my D3 5.5.0 Zopfli version instead of the best available CDN (6.55% smaller than cdnjs, 73805 vs. 78638 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 --i1000000 --mb8 --mls32768 --bsr4 --lazy --ohh

(found June 18, 2018)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 32768  --mls32768
block splitting recursion 4  --bsr4
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 2 more bytes (73803 bytes).

Verify file integrity

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

MD5:
curl --silent --compressed https://raw.githubusercontent.com/mbostock/d3/v5.5.0/d3.zip --location | md5sum
6422cecb9407dae02ca533c0d873633c  -
curl --silent --compressed https://minime.stephan-brumme.com/files/d3/d3-5.5.0.min.zopfli.js.gz | md5sum
6422cecb9407dae02ca533c0d873633c  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/mbostock/d3/v5.5.0/d3.zip --location | sha1sum
3d98ce7fe969090575df146aa64ef81e93a1eac8  -
curl --silent --compressed https://minime.stephan-brumme.com/files/d3/d3-5.5.0.min.zopfli.js.gz | sha1sum
3d98ce7fe969090575df146aa64ef81e93a1eac8  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
cdnjs 78638 bytes 6422cecb9407dae02ca533c0d873633c July 2, 2018 @ 12:30

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

Other Versions

Available D3 versions at minime.stephan-brumme.com:

5.5.0, 5.4.0, 5.3.0, 5.2.0, 5.1.0, 5.0.1, 5.0.0,
4.13.0, 4.12.2, 4.12.1, 4.12.0, 4.11.0, 4.10.2, 4.10.1, 4.10.0,
4.9.1, 4.9.0, 4.8.0, 4.7.4, 4.7.3, 4.7.2, 4.7.1, 4.7.0, 4.6.0, 4.5.0, 4.4.4, 4.4.3, 4.4.2, 4.4.1, 4.4.0, 4.3.0, 4.2.8, 4.2.7, 4.2.6, 4.2.5, 4.2.4, 4.2.3, 4.2.2, 4.2.1, 4.2.0, 4.1.1, 4.1.0, 4.0.0,
3.5.17, 3.5.16, 3.5.15, 3.5.14, 3.5.13, 3.5.12, 3.5.11, 3.5.10, 3.5.9, 3.5.8, 3.5.7, 3.5.6, 3.5.5, 3.5.4, 3.5.3, 3.5.2, 3.5.1, 3.5.0, 3.4.13, 3.4.12, 3.4.11, 3.4.10, 3.4.9, 3.4.8, 3.4.6, 3.4.5, 3.4.4, 3.4.3, 3.4.2, 3.4.1, 3.4.0, 3.3.13, 3.3.12, 3.3.11, 3.3.10, 3.3.9, 3.3.8, 3.3.7, 3.3.6, 3.3.5, 3.3.4, 3.3.3, 3.3.2, 3.3.1, 3.3.0, 3.2.8, 3.2.7, 3.2.6, 3.2.5, 3.2.4, 3.2.3, 3.2.2, 3.2.1, 3.2.0, 3.1.10, 3.1.9, 3.1.8, 3.1.7, 3.1.6, 3.1.5, 3.1.4, 3.1.3, 3.1.2, 3.1.1, 3.1.0, 3.0.8, 3.0.7, 3.0.6, 3.0.5, 3.0.4, 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, Bootstrap, Dojo, Ember, jQuery, Knockout, lodash, React, Socket.IO, ThreeJS, UnderscoreJS and Vue.

Changelog

Best Zopfli parameters so far:
Size Improvement Parameters Found
73805 bytes -6 bytes zopfli --i1000000 --mls32768 --bsr4 --lazy --ohh June 18, 2018 @ 21:41
73811 bytes -7 bytes zopfli --i100000 --mls32768 --bsr4 --lazy --ohh June 18, 2018 @ 09:23
73818 bytes -8 bytes zopfli --i10000 --mls32768 --bsr4 --lazy --ohh June 18, 2018 @ 08:07
73826 bytes -11 bytes zopfli --i1000 --mls32768 --bsr4 --lazy --ohh June 18, 2018 @ 07:47
73837 bytes zopfli --i100 --mls32768 --bsr4 --lazy --ohh June 18, 2018 @ 07:34

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

Most recent activity on July 2, 2018 @ 12:30.

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
74231 74228 74250 74292 74449 74263 74319 74336 74316 74324 74435 74342 74376 74135 74168
74449 74446 74454 74438 74441 74205 74488 74433 74454 74113 74080 73970 74094 73878 73805
73942 73936 73907 73921 73909 73883 73925 73945 73943 73947 73927 73918 73895 73863 74054
73963 73941 74058 74046 74056 73991 74101 74088 73994 73961 73893 74126 73874 74339 73966
73921 73921 73927 73903 73909 73900 73917 73918 73901 73896 73908 73920 73890 74062 74048
74001 73984 74007 74052 73943 74007 73985 73991 73907 74084 74043 74072 73918 74042 74095
73914 73922 73904 73915 73906 73912 73896 73914 73904 73914 73974 74127 74312 73882 74055
73958 73948 73872 73941 73911 73920 73899 74056 73917 74051 74049 74089 73910 74050 74086
73909 73913 73971 73956 73956 73961 73951 73955 73897 73939 73951 73905 73913 74052 74064
73913 73917 73915 73903 73912 73905 73904 73919 73905 73903 73925 74055 73985 74063 74038
73908 73916 73898 73900 73888 73894 73899 73893 73909 73932 73904 73905 73886 73989 73853
73983 73958 73950 73911 73994 73913 74101 73987 73960 74013 73977 74042 73941 74197 74044
73956 73951 73873 73863 73863 73906 73915 73944 73901 73897 73916 73904 73913 73898 74040
73924 73946 73912 73918 73905 73909 73901 73903 73913 73947 73950 73902 73914 74050 74043
73902 73917 73930 73943 73942 73940 73993 73993 73930 73957 73953 73895 73917 74188 74040
73904 73918 73908 73922 73908 73920 73898 73911 73900 73905 73955 73899 73916 73891 74055
73938 73953 73946 73917 73998 74001 73985 73992 73971 73932 74052 73918 73914 74042 74050
73903 73915 73901 73946 73905 73918 73903 73925 73901 73902 73951 74063 73918 73849 74039
73963 73954 73905 73905 73896 73900 73945 73947 73902 73923 73923 74045 73911 74052 73882
73952 73916 73906 73900 73912 73909 73899 73942 73900 73901 73925 74045 73912 73890 74047
73907 73915 73907 73900 73915 73924 73907 73901 73898 73903 73954 73911 74054 74051 74055
73922 73916 73903 73911 73901 73897 73914 73913 73902 73902 74050 74046 73914 74058 74058
73916 73919 73904 73916 73902 73913 73906 73919 73906 73910 74050 74056 73916 73893 74044

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 73837 bytes 100%
1,000 73826 bytes -11 bytes 100%
10,000 73818 bytes -8 bytes 100%
100,000 73811 bytes -7 bytes 0.87%
1,000,000 73805 bytes -6 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
73993 bytes +188 bytes (+0.25%) +221 bytes
75494 bytes +1689 bytes (+2.29%) +1722 bytes
75327 bytes +1522 bytes (+2.06%) +1555 bytes
74158 bytes +353 bytes (+0.48%) +386 bytes
74138 bytes +333 bytes (+0.45%) +366 bytes
74106 bytes +301 bytes (+0.41%) +334 bytes
73989 bytes +184 bytes (+0.25%) +217 bytes
73799 bytes -6 bytes (-0.01%) +27 bytes
73772 bytes -33 bytes (-0.04%)

Non-DEFLATE Algorithms

Archivers based on completely different compression algorithms often produce superior results.
Unfortunately, browsers only support gzip compression at the moment.
Algorithm Program Parameters Size Compared To Best Zopfli
ZPAQ (Wikipedia) zpaq zpaq -method 69 57843 bytes -15962 bytes (-21.63%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 64215 bytes -9590 bytes (-12.99%)
LZMA2 (Wikipedia) xz xz -9 65128 bytes -8677 bytes (-11.76%)
Brotli (Wikipedia) brotli brotli -q 11 65342 bytes -8463 bytes (-11.47%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 67334 bytes -6471 bytes (-8.77%)
Zstandard (Wikipedia) zstd zstd -19 70964 bytes -2841 bytes (-3.85%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 72838 bytes -967 bytes (-1.31%)

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 2018.
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