Choose a version:
46% The original file has 314716 bytes (307.3k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 144383 bytes (141.0k, 46%).

After GZIP compression these minified files vary in size:
Boot
  57144 bytes (55.8k)
CDN, direct link
Baidu
  50102 bytes (48.9k)
CDN, direct link
cdnjs
  50095 bytes (48.9k)
CDN, direct link
unpkg
  49713 bytes (48.5k)
CDN, direct link
gzip -6 (default)
  49696 bytes (48.5k)
local copy
cdnhttps
  49684 bytes (48.5k)
CDN, direct link
gzip -9
  49526 bytes (48.4k)
local copy
libdeflate -12
  47965 bytes (46.8k)
local copy
7zip -mx=9 -tgzip
  47920 bytes (46.8k)
local copy
pigz -11 -n
  47693 bytes (46.6k)
local copy
kzip -s0 -rn -b6
  47667 bytes (46.5k)
local copy
Zopfli
  47579 bytes (46.5k)
local copy
Zopfli (defluff)
  47578 bytes (46.5k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/d3/d3-3.3.0.min.js

You will automatically get the smallest D3 3.3.0 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 2105 bytes by using my D3 3.3.0 Zopfli version instead of the best available CDN (4.42% smaller than cdnhttps, 47579 vs. 49684 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 --i100000 --mb8 --mls64 --bsr13 --lazy --ohh

(found December 21, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 64  --mls64
block splitting recursion 13  --bsr13
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 (47578 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/v3.3.0/d3.min.js --location | md5sum
10a5f8ae5d7a89cd2d1dfa5a5984b511  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-3.3.0.min.zopfli.js.gz | md5sum
10a5f8ae5d7a89cd2d1dfa5a5984b511  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/mbostock/d3/v3.3.0/d3.min.js --location | sha1sum
827ca33cdb170319350141df1da09e1b01d7caa4  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-3.3.0.min.zopfli.js.gz | sha1sum
827ca33cdb170319350141df1da09e1b01d7caa4  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 57144 bytes 10a5f8ae5d7a89cd2d1dfa5a5984b511 (invalid)
cdnjs 50095 bytes 10a5f8ae5d7a89cd2d1dfa5a5984b511 (invalid)
unpkg 49713 bytes 10a5f8ae5d7a89cd2d1dfa5a5984b511 July 11, 2016 @ 16:32
cdnhttps 49684 bytes 10a5f8ae5d7a89cd2d1dfa5a5984b511 December 24, 2015 @ 07:33

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
Baidu 50102 bytes 5043c0b4580422857376b8c888b84118 only whitespaces differ (invalid)

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

Other Versions

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

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
47579 bytes -7 bytes zopfli --i100000 --mls64 --bsr13 --lazy --ohh December 21, 2015 @ 16:44
47586 bytes -6 bytes zopfli --i10000 --mls64 --bsr13 --lazy --ohh November 23, 2015 @ 17:41
47592 bytes -16 bytes zopfli --i1000 --mls64 --bsr13 --lazy --ohh September 20, 2015 @ 00:43
47608 bytes zopfli --i100 --mls16384 --bsr14 --lazy --ohh September 18, 2015 @ 19:47

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

Most recent activity on February 27, 2017 @ 10:21.

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 or 100,000.
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
47722 47731 47738 47691 47707 47738 47733 47732 47724 47730 47864 47838 47864 47741 47867
47709 47652 47687 47624 47660 47674 47625 47626 47678 47650 47861 47857 47859 47634 47858
47624 47697 47611 47614 47612 47613 47697 47723 47678 47629 47626 47620 47833 47690 47714
47607 47627 47611 47643 47608 47632 47679 47703 47712 47852 47618 47615 47845 47790 47693
47623 47610 47681 47623 47640 47636 47620 47692 47618 47723 47718 47715 47842 47857 47713
47622 47657 47615 47608 47622 47625 47630 47620 47621 47732 47623 47691 47845 47702 47707
47630 47622 47612 47616 47624 47644 47608 47634 47628 47615 47857 47772 47842 47684 47847
47614 47609 47610 47614 47610 47610 47678 47618 47674 47852 47616 47620 47840 47771 47695
47625 47650 47610 47609 47608 47607 47621 47621 47625 47598 47619 47619 47843 47736 47706
47620 47653 47611 47613 47610 47579 47619 47627 47628 47627 47621 47695 47834 47644 47700
47618 47629 47646 47615 47611 47620 47685 47625 47624 47620 47621 47695 47859 47593 47703
47635 47592 47611 47619 47612 47614 47688 47621 47672 47591 47617 47612 47844 47681 47698
47630 47613 47603 47611 47608 47611 47682 47627 47671 47623 47624 47775 47844 47686 47707
47623 47581 47616 47613 47608 47614 47614 47681 47618 47619 47620 47621 47841 47854 47703
47616 47645 47611 47650 47620 47659 47608 47618 47622 47626 47620 47652 47843 47853 47848
47636 47659 47616 47622 47613 47616 47618 47683 47624 47618 47618 47615 47845 47854 47843
47629 47655 47610 47615 47615 47624 47679 47673 47623 47626 47683 47694 47845 47685 47701
47594 47603 47612 47614 47610 47609 47653 47684 47627 47630 47624 47743 47844 47689 47848
47624 47650 47613 47616 47617 47607 47681 47680 47620 47620 47616 47605 47844 47687 47708
47627 47634 47611 47620 47618 47590 47626 47688 47665 47617 47622 47682 47848 47682 47702
47638 47582 47594 47614 47608 47607 47620 47621 47623 47614 47618 47679 47844 47753 47703
47627 47642 47620 47616 47612 47608 47616 47690 47627 47629 47618 47629 47833 47591 47850
47645 47602 47612 47631 47608 47613 47645 47684 47624 47626 47618 47620 47845 47685 47707

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 47604 bytes 100%
1,000 47592 bytes -12 bytes 100%
10,000 47586 bytes -6 bytes 100%
100,000 47579 bytes -7 bytes 0.87%
1,000,000
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
47883 bytes +304 bytes (+0.64%) +216 bytes
47885 bytes +306 bytes (+0.64%) +218 bytes
47888 bytes +309 bytes (+0.65%) +221 bytes
47806 bytes +227 bytes (+0.48%) +139 bytes
47814 bytes +235 bytes (+0.49%) +147 bytes
47679 bytes +100 bytes (+0.21%) +12 bytes
47667 bytes +88 bytes (+0.18%)
47687 bytes +108 bytes (+0.23%) +20 bytes
47697 bytes +118 bytes (+0.25%) +30 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 38173 bytes -9406 bytes (-19.77%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 40374 bytes -7205 bytes (-15.14%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 41062 bytes -6517 bytes (-13.70%)
Brotli (Wikipedia) brotli brotli -q 11 43038 bytes -4541 bytes (-9.54%)
LZMA2 (Wikipedia) xz xz -9 43772 bytes -3807 bytes (-8.00%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 45563 bytes -2016 bytes (-4.24%)
ZSTD (Wikipedia) zstd zstd -19 46066 bytes -1513 bytes (-3.18%)

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 2017.
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