Choose a version:
48% The original file has 447361 bytes (436.9k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 212661 bytes (207.7k, 48%).

After GZIP compression these minified files vary in size:
Boot
  81472 bytes (79.6k)
CDN
cdnjs
  72011 bytes (70.3k)
CDN
cdnhttps
  71796 bytes (70.1k)
CDN
gzip -6 (default)
  71417 bytes (69.7k)
local copy
gzip -9
  71180 bytes (69.5k)
local copy
libdeflate -12
  68444 bytes (66.8k)
local copy
7zip -mx=9 -tgzip
  67998 bytes (66.4k)
local copy
kzip -s0 -rn -b8
  67621 bytes (66.0k)
local copy
pigz -11 -n
  67557 bytes (66.0k)
local copy
Zopfli
  67504 bytes (65.9k)
local copy
Zopfli (defluff)
  67503 bytes (65.9k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/d3/d3-4.2.7.min.js (or via HTTPS)

You will automatically get the smallest D3 4.2.7 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 4292 bytes by using my D3 4.2.7 Zopfli version instead of the best available CDN (6.36% smaller than cdnhttps, 67504 vs. 71796 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 --mls8192 --bsr9 --lazy --ohh

(found October 13, 2016)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 8192  --mls8192
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 1 more byte (67503 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/v4.2.7/d3.zip --location | md5sum
817759e6bca94d58c55da341e4944106  -
curl --silent --compressed https://minime.stephan-brumme.com/files/d3/d3-4.2.7.min.zopfli.js.gz | md5sum
817759e6bca94d58c55da341e4944106  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/mbostock/d3/v4.2.7/d3.zip --location | sha1sum
c98b85fb867c19a7080b3f7c120150b3dad0fff9  -
curl --silent --compressed https://minime.stephan-brumme.com/files/d3/d3-4.2.7.min.zopfli.js.gz | sha1sum
c98b85fb867c19a7080b3f7c120150b3dad0fff9  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 81472 bytes 817759e6bca94d58c55da341e4944106 October 12, 2016 @ 16:18
cdnjs 72011 bytes 817759e6bca94d58c55da341e4944106 October 11, 2016 @ 18:17
cdnhttps 71796 bytes 817759e6bca94d58c55da341e4944106 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:

5.7.0, 5.6.0, 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
67504 bytes -3 bytes zopfli --i1000000 --mls8192 --bsr9 --lazy --ohh October 13, 2016 @ 11:45
67507 bytes -7 bytes zopfli --i100000 --mls8192 --bsr9 --lazy --ohh October 12, 2016 @ 20:44
67514 bytes -12 bytes zopfli --i10000 --mls8192 --bsr9 --lazy --ohh October 12, 2016 @ 11:16
67526 bytes -13 bytes zopfli --i1000 --mls8192 --bsr9 --lazy --ohh October 12, 2016 @ 10:39
67539 bytes zopfli --i100 --mls8192 --bsr9 --lazy --ohh October 12, 2016 @ 00:29

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

Most recent activity on January 25, 2017 @ 15:29.

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
67731 67728 67867 67799 67798 67806 67799 67805 67835 67904 68003 68021 68028 67930 67921
67685 67706 67552 68416 67699 67790 67577 67652 67677 67571 67630 67565 67574 67624 67687
67669 67662 67671 68391 68390 67664 67656 67667 67719 67663 67538 67646 67606 68379 67707
67514 67699 67638 67661 67650 68368 67649 67673 67521 67635 67634 68346 67514 68382 67688
67761 67772 67657 67655 68360 68369 67651 67655 67657 67676 67631 68353 67517 68379 67636
67671 67730 67673 67664 67669 67660 67634 67641 67633 67631 67623 68336 67504 68383 68370
67634 67663 67674 68350 67620 67635 67630 67624 67627 67628 67649 67700 67644 67689 67678
67669 67671 67639 68338 68336 68338 67626 67629 67637 67638 67628 67638 67660 67733 67543
67638 67640 67639 68338 68352 68345 67634 67623 67625 67637 67703 68328 68341 68359 67719
67628 67636 67642 68344 68343 68337 67625 67633 68341 67629 67622 67633 68355 68358 67689
67637 67638 67632 68361 67637 68345 67624 67626 67623 67639 67641 68335 67632 68351 67693
67625 67647 67633 68342 68338 68341 67635 67624 67633 67633 67632 67626 67638 68362 67718
67638 67646 67634 68349 68353 68341 67622 68343 67631 67639 67632 68338 67653 68348 67689
67637 67634 67634 68339 68349 68356 67631 67632 67640 67632 67629 67640 67675 68357 68349
67624 67632 67633 68359 68352 68337 67626 67626 67633 67628 67665 67707 67659 67661 67694
67650 67627 67633 68343 68353 67633 67629 67623 67638 67628 67630 68341 67666 68365 68356
67632 67633 67631 68343 68353 68336 67628 67630 67633 67634 68329 67637 67628 68352 67695
67639 67642 67623 68357 68355 67632 67634 67625 67633 67632 67628 67641 67662 68359 67694
67640 67643 67641 68342 68355 68340 67622 67655 67636 67630 67623 67633 67625 68353 67690
67632 67636 67636 68341 68342 67633 67625 67648 67633 67638 67620 68333 67671 68379 67690
67636 67646 67636 68344 68344 67633 67625 67627 67640 67634 68337 68344 67646 67699 67685
67644 67632 67640 68368 68337 68357 67628 67624 67641 67659 67629 67673 67660 68360 67689
67655 67636 67659 68342 68339 68352 67665 67660 67626 67624 67697 68333 67675 67687 67694

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 67539 bytes 100%
1,000 67526 bytes -13 bytes 100%
10,000 67514 bytes -12 bytes 100%
100,000 67507 bytes -7 bytes 1.45%
1,000,000 67504 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
67639 bytes +135 bytes (+0.20%) +18 bytes
69089 bytes +1585 bytes (+2.35%) +1468 bytes
68954 bytes +1450 bytes (+2.15%) +1333 bytes
68583 bytes +1079 bytes (+1.60%) +962 bytes
67890 bytes +386 bytes (+0.57%) +269 bytes
67780 bytes +276 bytes (+0.41%) +159 bytes
67782 bytes +278 bytes (+0.41%) +161 bytes
67637 bytes +133 bytes (+0.20%) +16 bytes
67621 bytes +117 bytes (+0.17%)

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
ZPAQ (Wikipedia) zpaq zpaq -method 69 53491 bytes -14013 bytes (-20.76%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 59462 bytes -8042 bytes (-11.91%)
LZMA2 (Wikipedia) xz xz -9 60224 bytes -7280 bytes (-10.78%)
Brotli (Wikipedia) brotli brotli -q 11 60360 bytes -7144 bytes (-10.58%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 61810 bytes -5694 bytes (-8.44%)
Zstandard (Wikipedia) zstd zstd -19 65540 bytes -1964 bytes (-2.91%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 66870 bytes -634 bytes (-0.94%)

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