Choose a version:
45% The original file has 471025 bytes (460.0k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 211573 bytes (206.6k, 45%).

After GZIP compression these minified files vary in size:
Boot
  80496 bytes (78.6k)
CDN
cdnjs
  70747 bytes (69.1k)
CDN
cdnhttps
  70509 bytes (68.9k)
CDN
gzip -6 (default)
  70186 bytes (68.5k)
local copy
gzip -9
  69968 bytes (68.3k)
local copy
libdeflate -12
  67304 bytes (65.7k)
local copy
7zip -mx=9 -tgzip
  66936 bytes (65.4k)
local copy
kzip -s0 -rn -b8
  66535 bytes (65.0k)
local copy
pigz -11 -n
  66503 bytes (64.9k)
local copy
Zopfli
  66400 bytes (64.8k)
local copy
Zopfli (defluff)
  66397 bytes (64.8k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/d3/d3-4.2.2.min.js

You will automatically get the smallest D3 4.2.2 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 4109 bytes by using my D3 4.2.2 Zopfli version instead of the best available CDN (6.19% smaller than cdnhttps, 66400 vs. 70509 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 --mls512 --bsr12 --lazy --ohh

(found August 17, 2016)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 512  --mls512
block splitting recursion 12  --bsr12
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 3 more bytes (66397 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/v4.2.2/d3.zip --location | md5sum
47301e9524d1ffd4079919d14d01b32e  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-4.2.2.min.zopfli.js.gz | md5sum
47301e9524d1ffd4079919d14d01b32e  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/mbostock/d3/v4.2.2/d3.zip --location | sha1sum
48a511f6ba6e845121c082ad47405b7402856eb7  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-4.2.2.min.zopfli.js.gz | sha1sum
48a511f6ba6e845121c082ad47405b7402856eb7  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 80496 bytes 47301e9524d1ffd4079919d14d01b32e August 20, 2016 @ 16:16
cdnjs 70747 bytes 47301e9524d1ffd4079919d14d01b32e August 16, 2016 @ 06:31
cdnhttps 70509 bytes 47301e9524d1ffd4079919d14d01b32e November 22, 2016 @ 16:32

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

Other Versions

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

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
66400 bytes -2 bytes zopfli --i1000000 --mls512 --bsr12 --lazy --ohh August 17, 2016 @ 03:40
66402 bytes -1 byte zopfli --i100000 --mls512 --bsr12 --lazy --ohh August 16, 2016 @ 13:56
66403 bytes -5 bytes zopfli --i100000 --mls512 --bsr14 --lazy --ohh August 16, 2016 @ 11:25
66408 bytes -8 bytes zopfli --i10000 --mls512 --bsr14 --lazy --ohh August 16, 2016 @ 10:09
66416 bytes -21 bytes zopfli --i1000 --mls512 --bsr14 --lazy --ohh August 16, 2016 @ 09:58
66437 bytes zopfli --i100 --mls512 --bsr14 --lazy --ohh August 16, 2016 @ 09:48

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

Most recent activity on November 22, 2016 @ 16:32.

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
66754 66756 66625 66640 66635 66634 66576 66627 66570 66556 66645 66639 66766 66713 66700
66551 66569 66549 66545 66545 66544 66549 66475 66469 66443 66447 66473 66605 66508 66602
66648 66517 66612 66611 66526 66602 66437 66532 66477 66420 66437 66424 66567 66424 66575
66547 66608 66627 66604 66523 66527 66522 66517 66534 66473 66436 66444 66587 66439 66550
66607 66606 67124 67122 67109 67118 66515 66531 66417 66415 66428 66421 66552 66543 66440
67126 66603 66620 66605 66526 66539 66520 66518 66407 66464 66426 66424 66573 66464 66569
66529 66512 66609 66624 66533 67104 66523 66538 66404 66406 66432 66426 66573 66538 66547
66616 66602 66612 66611 66528 67102 66520 66514 66529 66413 66437 66442 66567 66476 66589
66542 66605 66597 66614 66612 66622 66526 66513 66400 66419 66434 66423 66572 66497 66553
66599 66531 66601 66595 66527 66601 66529 66513 66527 66413 66427 66407 66559 66562 66592
66625 66617 66612 66624 66468 66607 66466 66516 66403 66415 66441 66436 66578 66456 66567
66625 66604 67422 66613 66521 66520 66554 66536 66440 66416 66430 66443 66568 66568 66570
66617 66601 66609 66601 66528 66601 66517 66520 66415 66501 66507 66429 66561 66453 66539
67123 66605 66610 66629 66459 66526 66466 66513 66519 66417 66435 66423 66558 66460 66532
66621 67114 67115 66611 66528 66539 66533 66519 66451 66412 66419 66419 66561 66471 66572
66620 66612 66622 67119 66530 67116 66519 66516 66414 66418 66433 66427 66592 66542 66548
66609 66612 66625 66608 66517 66522 66519 66515 66414 66414 66430 66427 66561 66466 66571
67117 66604 66622 66601 66534 66601 66523 66517 66412 66417 66424 66433 66562 66436 66538
66614 67107 66607 67114 66529 66611 66519 66517 66404 66419 66429 66472 66584 66533 66546
66613 66608 66622 66616 66528 67107 66466 66520 66405 66420 66421 66419 66550 66494 66549
66608 66610 66622 66600 66528 66600 66521 66514 66414 66418 66435 66423 66561 66559 66565
66637 66631 66644 66619 66456 66614 66466 66467 66466 66445 66434 66430 66562 66495 66548
66623 66614 66627 66619 67118 66616 66529 66522 66415 66416 66437 66428 66570 66461 66589

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 66437 bytes 100%
1,000 66416 bytes -21 bytes 100%
10,000 66408 bytes -8 bytes 100%
100,000 66402 bytes -6 bytes 2.32%
1,000,000 66400 bytes -2 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
66599 bytes +199 bytes (+0.30%) +64 bytes
68088 bytes +1688 bytes (+2.54%) +1553 bytes
67578 bytes +1178 bytes (+1.77%) +1043 bytes
67194 bytes +794 bytes (+1.20%) +659 bytes
66701 bytes +301 bytes (+0.45%) +166 bytes
66695 bytes +295 bytes (+0.44%) +160 bytes
66576 bytes +176 bytes (+0.27%) +41 bytes
66597 bytes +197 bytes (+0.30%) +62 bytes
66535 bytes +135 bytes (+0.20%)

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 52744 bytes -13656 bytes (-20.57%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 59087 bytes -7313 bytes (-11.01%)
LZMA2 (Wikipedia) xz xz -9 59604 bytes -6796 bytes (-10.23%)
Brotli (Wikipedia) brotli brotli -q 11 59809 bytes -6591 bytes (-9.93%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 60582 bytes -5818 bytes (-8.76%)
ZSTD (Wikipedia) zstd zstd -19 64886 bytes -1514 bytes (-2.28%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 66450 bytes +50 bytes (+0.08%)

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