Choose a version:
47% The original file has 450780 bytes (440.2k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 213974 bytes (209.0k, 47%).

After GZIP compression these minified files vary in size:
Boot
  82288 bytes (80.4k)
CDN
cdnjs
  72839 bytes (71.1k)
CDN
gzip -6 (default)
  72354 bytes (70.7k)
local copy
jsdelivr
  72227 bytes (70.5k)
CDN
gzip -9
  72076 bytes (70.4k)
local copy
libdeflate -12
  69309 bytes (67.7k)
local copy
7zip -mx=9 -tgzip
  68976 bytes (67.4k)
local copy
kzip -s0 -rn -b7
  68699 bytes (67.1k)
local copy
pigz -11 -n
  68524 bytes (66.9k)
local copy
Zopfli
  68445 bytes (66.8k)
local copy
Zopfli (defluff)
  68443 bytes (66.8k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/d3/d3-4.4.4.min.js

You will automatically get the smallest D3 4.4.4 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 3782 bytes by using my D3 4.4.4 Zopfli version instead of the best available CDN (5.53% smaller than jsdelivr, 68445 vs. 72227 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 --bsr9 --lazy --ohh

(found January 26, 2017)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 512  --mls512
block splitting recursion 9  --bsr9
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 (68443 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/v4.4.4/d3.zip --location | md5sum
ed085ba79e4ba1b7f6b8d438edffdd72  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-4.4.4.min.zopfli.js.gz | md5sum
ed085ba79e4ba1b7f6b8d438edffdd72  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/mbostock/d3/v4.4.4/d3.zip --location | sha1sum
296fd2f15f58946cad3108d0c9b8c9046476ad39  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-4.4.4.min.zopfli.js.gz | sha1sum
296fd2f15f58946cad3108d0c9b8c9046476ad39  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 82288 bytes ed085ba79e4ba1b7f6b8d438edffdd72 January 29, 2017 @ 13:12
cdnjs 72839 bytes ed085ba79e4ba1b7f6b8d438edffdd72 January 23, 2017 @ 20:02
jsdelivr 72227 bytes ed085ba79e4ba1b7f6b8d438edffdd72 January 23, 2017 @ 20:03

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
68445 bytes -5 bytes zopfli --i1000000 --mls512 --bsr9 --lazy --ohh January 26, 2017 @ 23:17
68450 bytes -9 bytes zopfli --i100000 --mls512 --bsr9 --lazy --ohh January 25, 2017 @ 14:20
68459 bytes -1 byte zopfli --i10000 --mls512 --bsr9 --lazy --ohh January 25, 2017 @ 13:01
68460 bytes -1 byte zopfli --i10000 --mls64 --bsr14 --lazy --ohh January 25, 2017 @ 12:53
68461 bytes -10 bytes zopfli --i10000 --mls2 --bsr19 --lazy --ohh January 25, 2017 @ 12:30
68471 bytes -2 bytes zopfli --i1000 --mls512 --bsr12 --lazy --ohh January 25, 2017 @ 12:27
68473 bytes -2 bytes zopfli --i1000 --mls2 --bsr20 --lazy --ohh January 25, 2017 @ 12:23
68475 bytes -12 bytes zopfli --i1000 --mls2 --bsr19 --lazy --ohh January 25, 2017 @ 12:23
68487 bytes zopfli --i100 --mls2 --bsr19 --lazy --ohh January 25, 2017 @ 11:45

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

Most recent activity on January 29, 2017 @ 13:12.

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
68752 68890 68771 68816 68782 68828 68728 68813 68784 68731 68725 68702 68686 68699 68670
68729 68495 68525 68512 68555 68558 68652 68516 68619 68636 68627 68625 68621 68640 68611
68478 68611 68475 68473 68465 68547 68502 68588 68620 68621 68611 68622 68634 68610 68622
68527 68578 68527 68535 68551 68505 68829 68495 68486 68628 68615 68614 68639 68626 68615
68531 68562 68607 68548 68553 68550 68678 68606 68624 68615 68641 68626 68625 68618 68652
68463 68606 68608 68600 68461 68468 68476 68604 68445 68606 68607 68616 68637 68634 68617
68466 68611 68610 68474 69532 69535 69535 68607 68599 68619 68610 68619 68633 68609 68617
68462 68610 69512 68471 68551 68550 68603 68614 68454 68630 68618 68616 68568 68607 68607
68519 68516 68617 68472 68546 68548 68676 68605 68461 68605 68609 68618 68613 68635 68609
68482 68623 68607 68463 68549 68461 68651 68621 68493 68598 68618 68620 68614 68631 68611
68612 68553 68607 68546 68612 68454 68642 68590 68463 68613 68608 68614 68606 68624 68615
68462 68606 68609 68467 68545 68549 68692 68605 68466 68593 68623 68619 68630 68608 68634
68575 68570 68560 68553 68605 68548 68607 68609 68463 68602 68612 68617 68608 68584 68614
68455 68599 68610 68454 69524 68676 68688 68605 68461 68592 68613 68617 68587 68589 68581
68461 68610 69535 68473 68597 68609 68605 68609 68599 68596 68613 68628 68618 68618 68618
68461 68602 68608 68467 68677 68684 68693 68603 68594 68566 68608 68617 68588 68589 68578
68455 68607 68610 68546 68596 68548 68641 68615 68599 68592 68610 68616 68602 68589 68616
68465 68608 68651 68468 68621 68468 68695 68619 68597 68560 68610 68614 68573 68586 68578
68469 68599 68609 68545 68551 68546 68658 68608 68597 68570 68616 68618 68581 68604 68580
68461 68606 68609 68471 68602 68467 68547 68466 68461 68567 68610 68615 68607 68585 68577
68464 68609 68475 68474 68612 68550 68577 68615 68469 68569 68572 68583 68582 68582 68579
68462 68610 69535 68477 69528 68705 68646 68574 68608 68592 68573 68584 68603 68588 68575
68461 68548 68611 68549 68544 68549 68461 68606 68461 68593 68574 68582 68608 68588 68618

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 68487 bytes 100%
1,000 68466 bytes -21 bytes 100%
10,000 68459 bytes -7 bytes 100%
100,000 68450 bytes -9 bytes 1.74%
1,000,000 68445 bytes -5 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
68710 bytes +265 bytes (+0.39%) +11 bytes
70016 bytes +1571 bytes (+2.30%) +1317 bytes
69707 bytes +1262 bytes (+1.84%) +1008 bytes
68836 bytes +391 bytes (+0.57%) +137 bytes
68717 bytes +272 bytes (+0.40%) +18 bytes
68725 bytes +280 bytes (+0.41%) +26 bytes
68743 bytes +298 bytes (+0.44%) +44 bytes
68699 bytes +254 bytes (+0.37%)
68707 bytes +262 bytes (+0.38%) +8 bytes

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 53817 bytes -14628 bytes (-21.37%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 59910 bytes -8535 bytes (-12.47%)
LZMA2 (Wikipedia) xz xz -9 60724 bytes -7721 bytes (-11.28%)
Brotli (Wikipedia) brotli brotli -q 11 60962 bytes -7483 bytes (-10.93%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 61850 bytes -6595 bytes (-9.64%)
ZSTD (Wikipedia) zstd zstd -19 66100 bytes -2345 bytes (-3.43%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 67303 bytes -1142 bytes (-1.67%)

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