Choose a version:
48% The original file has 493246 bytes (481.7k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 235672 bytes (230.1k, 48%).

After GZIP compression these minified files vary in size:
cdnjs
  78301 bytes (76.5k)
CDN
gzip -6 (default)
  77772 bytes (75.9k)
local copy
gzip -9
  77514 bytes (75.7k)
local copy
libdeflate -12
  74141 bytes (72.4k)
local copy
7zip -mx=9 -tgzip
  74018 bytes (72.3k)
local copy
pigz -11 -n
  73500 bytes (71.8k)
local copy
kzip -s0 -rn -b8
  73471 bytes (71.7k)
local copy
Zopfli
  73458 bytes (71.7k)
local copy
Zopfli (defluff)
  73456 bytes (71.7k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/d3/d3-5.1.0.min.js (or via HTTPS)

You will automatically get the smallest D3 5.1.0 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 4843 bytes by using my D3 5.1.0 Zopfli version instead of the best available CDN (6.59% smaller than cdnjs, 73458 vs. 78301 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 --mls1024 --bsr6 --lazy --ohh

(found April 25, 2018)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 1024  --mls1024
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

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 (73456 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/v5.1.0/d3.zip --location | md5sum
58c4db79af8ab035d60c1995027093e4  -
curl --silent --compressed https://minime.stephan-brumme.com/files/d3/d3-5.1.0.min.zopfli.js.gz | md5sum
58c4db79af8ab035d60c1995027093e4  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/mbostock/d3/v5.1.0/d3.zip --location | sha1sum
3255f0f3fdb3cde2be73e5b0eda8d0a54c0f05a7  -
curl --silent --compressed https://minime.stephan-brumme.com/files/d3/d3-5.1.0.min.zopfli.js.gz | sha1sum
3255f0f3fdb3cde2be73e5b0eda8d0a54c0f05a7  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
cdnjs 78301 bytes 58c4db79af8ab035d60c1995027093e4 July 2, 2018 @ 19:00

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
73458 bytes -3 bytes zopfli --i1000000 --mls1024 --bsr6 --lazy --ohh April 25, 2018 @ 22:55
73461 bytes -8 bytes zopfli --i100000 --mls1024 --bsr6 --lazy --ohh April 24, 2018 @ 21:27
73469 bytes -18 bytes zopfli --i10000 --mls1024 --bsr6 --lazy --ohh April 23, 2018 @ 15:49
73487 bytes -9 bytes zopfli --i1000 --mls1024 --bsr6 --lazy --ohh April 23, 2018 @ 09:59
73496 bytes zopfli --i100 --mls1024 --bsr6 --lazy --ohh April 23, 2018 @ 09:12

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 @ 19:00.

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
73779 73913 73944 74133 74133 73916 73980 73854 73982 74017 74146 74079 74085 73815 73836
74158 74148 74193 74191 74187 74190 74187 73778 73808 74174 73688 73666 73805 73816 73818
73637 73627 73601 73596 73586 73621 73617 73611 73622 73458 73658 73734 73591 73640 73740
73649 73647 73660 73650 73735 73675 73744 73752 73785 73608 73688 73836 73817 73784 73739
73607 73623 73591 73596 73738 73734 73601 73618 73598 73615 73604 73580 73593 73590 73744
73644 73642 73702 73641 73732 73632 73635 73696 73667 73754 73719 73665 73657 73662 73790
73662 73669 73590 73592 73611 73592 73608 73613 73738 73776 73675 73842 73617 73919 73867
73619 73651 73631 73558 73695 73750 73751 73751 73748 73750 73773 73779 73689 73584 73786
73586 73578 73672 73640 73644 73648 73647 73655 73595 73614 73744 73578 73605 73732 73734
73629 73630 73584 73605 73608 73599 73613 73616 73597 73739 73737 73777 73778 73780 73741
73611 73620 73585 73578 73594 73597 73610 73611 73583 73622 73589 73583 73592 73565 73594
73646 73652 73650 73578 73696 73603 73765 73627 73750 73635 73663 73767 73776 73557 73741
73657 73657 73556 73558 73562 73592 73638 73608 73599 73619 73610 73631 73578 73740 73743
73640 73642 73581 73582 73589 73595 73613 73642 73591 73621 73704 73579 73583 73746 73739
73650 73623 73641 73620 73627 73583 73696 73624 73670 73619 73481 73592 73597 73881 73739
73622 73616 73591 73589 73593 73595 73598 73622 73611 73615 73603 73584 73581 73584 73754
73646 73632 73649 73659 73604 73624 73694 73628 73680 73760 73665 73583 73610 73602 73569
73634 73637 73585 73586 73591 73594 73609 73610 73597 73623 73775 73778 73621 73902 73753
73641 73641 73595 73590 73598 73598 73638 73663 73598 73667 73769 73770 73604 73745 73583
73636 73623 73629 73635 73634 73635 73633 73638 73594 73750 73771 73666 73610 73582 73751
73614 73585 73587 73585 73594 73596 73611 73614 73596 73603 73770 73575 73755 73744 73738
73619 73629 73580 73585 73608 73596 73608 73611 73594 73622 73663 73774 73605 73766 73758
73619 73617 73591 73590 73612 73596 73619 73615 73595 73615 73766 73770 73590 73587 73740

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 73496 bytes 100%
1,000 73487 bytes -9 bytes 100%
10,000 73469 bytes -18 bytes 100%
100,000 73461 bytes -8 bytes 0.87%
1,000,000 73458 bytes -3 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
73686 bytes +228 bytes (+0.31%) +215 bytes
75198 bytes +1740 bytes (+2.37%) +1727 bytes
75029 bytes +1571 bytes (+2.14%) +1558 bytes
73857 bytes +399 bytes (+0.54%) +386 bytes
73831 bytes +373 bytes (+0.51%) +360 bytes
73800 bytes +342 bytes (+0.47%) +329 bytes
73690 bytes +232 bytes (+0.32%) +219 bytes
73500 bytes +42 bytes (+0.06%) +29 bytes
73471 bytes +13 bytes (+0.02%)

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 57610 bytes -15848 bytes (-21.57%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 63951 bytes -9507 bytes (-12.94%)
LZMA2 (Wikipedia) xz xz -9 64892 bytes -8566 bytes (-11.66%)
Brotli (Wikipedia) brotli brotli -q 11 65092 bytes -8366 bytes (-11.39%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 67029 bytes -6429 bytes (-8.75%)
Zstandard (Wikipedia) zstd zstd -19 70713 bytes -2745 bytes (-3.74%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 72525 bytes -933 bytes (-1.27%)

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