Choose a version:
46% The original file has 315352 bytes (308.0k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 144745 bytes (141.4k, 46%).

After GZIP compression these minified files vary in size:
Boot
  57346 bytes (56.0k)
CDN, direct link
Baidu
  50267 bytes (49.1k)
CDN, direct link
cdnjs
  50256 bytes (49.1k)
CDN, direct link
unpkg
  49859 bytes (48.7k)
CDN, direct link
gzip -6 (default)
  49851 bytes (48.7k)
local copy
cdnhttps
  49836 bytes (48.7k)
CDN, direct link
gzip -9
  49675 bytes (48.5k)
local copy
libdeflate -12
  48114 bytes (47.0k)
local copy
7zip -mx=9 -tgzip
  48014 bytes (46.9k)
local copy
kzip -s0 -rn -b5
  47823 bytes (46.7k)
local copy
pigz -11 -n
  47816 bytes (46.7k)
local copy
Zopfli
  47693 bytes (46.6k)
local copy
Zopfli (defluff)
  47691 bytes (46.6k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/d3/d3-3.3.5.min.js

You will automatically get the smallest D3 3.3.5 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 2143 bytes by using my D3 3.3.5 Zopfli version instead of the best available CDN (4.49% smaller than cdnhttps, 47693 vs. 49836 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 --mls2 --bsr12 --lazy --ohh

(found December 21, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 2  --mls2
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 2 more bytes (47691 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/v3.3.5/d3.min.js --location | md5sum
d733da10a25e820e0bd90a3b397a948a  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-3.3.5.min.zopfli.js.gz | md5sum
d733da10a25e820e0bd90a3b397a948a  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/mbostock/d3/v3.3.5/d3.min.js --location | sha1sum
6ee01abea3702e369cba49956eef4fa47989b8c3  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-3.3.5.min.zopfli.js.gz | sha1sum
6ee01abea3702e369cba49956eef4fa47989b8c3  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 57346 bytes d733da10a25e820e0bd90a3b397a948a (invalid)
cdnjs 50256 bytes d733da10a25e820e0bd90a3b397a948a (invalid)
unpkg 49859 bytes d733da10a25e820e0bd90a3b397a948a July 11, 2016 @ 16:31
cdnhttps 49836 bytes d733da10a25e820e0bd90a3b397a948a December 24, 2015 @ 07:33

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
Baidu 50267 bytes 31cdf379ea7ce8c6c447fd2861157375 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:

4.10.0,
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
47693 bytes -8 bytes zopfli --i100000 --mls2 --bsr12 --lazy --ohh December 21, 2015 @ 18:44
47701 bytes -2 bytes zopfli --i10000 --mls2 --bsr12 --lazy --ohh September 23, 2015 @ 19:49
47703 bytes -21 bytes zopfli --i1000 --mls2 --bsr12 --lazy --ohh September 23, 2015 @ 07:54
47724 bytes zopfli --i100 --mls2 --bsr12 --lazy --ohh September 22, 2015 @ 11:22

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 @ 10:35.

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
47812 47808 47855 47824 47827 47897 47891 47842 47869 47895 47895 47983 48005 47855 48001
47736 47796 47788 47784 47770 47761 47752 47804 47758 47758 47764 47746 47999 47790 48010
47734 47798 47785 47747 47798 47771 47795 47786 47784 47845 47767 47752 47976 47780 47877
47786 47824 47810 47796 47753 47748 47773 47743 47783 47781 47769 47753 47998 47833 47861
47737 47801 47822 47728 47771 47797 47808 47843 47771 47850 47848 47861 48004 47847 48009
47739 47825 47786 47754 47757 47794 47800 47793 47757 47751 47766 47745 47994 47856 48009
47783 47796 47786 47780 47803 47748 47829 47785 47804 47749 47764 47922 47998 47788 47859
47739 47814 47768 47745 47724 47789 47794 47781 47795 47852 47762 47751 47980 47740 47850
47693 47769 47767 47749 47796 47740 47787 47798 47799 47748 47759 47739 47998 47753 48007
47739 47799 47742 47745 47753 47763 47791 47805 47819 47752 47760 47754 47998 47753 47861
47752 47810 47773 47756 47747 47739 47791 47751 47821 47752 47762 47750 47998 47751 47860
47745 47802 47791 47780 47754 47794 47788 47848 47735 47753 47770 47743 47998 47734 47846
47747 47833 47766 47742 47743 47732 47791 47797 47795 47753 47743 47917 47998 47729 47852
47750 47816 47770 47744 47751 47749 47746 47745 47809 47751 47764 47752 47998 47758 47860
47776 47801 47818 47744 47756 47761 47802 47745 47782 47755 47761 47750 47998 47734 47870
47803 47814 47819 47744 47722 47787 47811 47813 47790 47755 47769 47742 47998 47749 47865
47738 47801 47768 47744 47743 47797 47790 47795 47754 47749 47767 47754 47979 48008 47869
47738 47794 47770 47748 47800 47764 47829 47772 47794 47754 47766 47757 47998 47761 47858
47749 47829 47767 47751 47751 47790 47801 47796 47781 47759 47764 47921 48000 47768 47861
47748 47788 47767 47745 47753 47791 47790 47797 47798 47750 47765 47756 47983 47738 47857
47793 47737 47789 47742 47763 47792 47776 47792 47795 47753 47760 47748 47998 47758 47852
47750 47778 47815 47747 47756 47793 47794 47798 47799 47752 47762 47753 47998 47760 47873
47759 47831 47755 47745 47756 47736 47789 47801 47789 47757 47765 47919 47998 47750 47863

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 47724 bytes 100%
1,000 47703 bytes -21 bytes 100%
10,000 47701 bytes -2 bytes 100%
100,000 47693 bytes -8 bytes 0.29%
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
48024 bytes +331 bytes (+0.69%) +201 bytes
48026 bytes +333 bytes (+0.70%) +203 bytes
48032 bytes +339 bytes (+0.71%) +209 bytes
47947 bytes +254 bytes (+0.53%) +124 bytes
47959 bytes +266 bytes (+0.56%) +136 bytes
47823 bytes +130 bytes (+0.27%)
47845 bytes +152 bytes (+0.32%) +22 bytes
47831 bytes +138 bytes (+0.29%) +8 bytes
47835 bytes +142 bytes (+0.30%) +12 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 38257 bytes -9436 bytes (-19.78%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 40479 bytes -7214 bytes (-15.13%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 41197 bytes -6496 bytes (-13.62%)
Brotli (Wikipedia) brotli brotli -q 11 43187 bytes -4506 bytes (-9.45%)
LZMA2 (Wikipedia) xz xz -9 43912 bytes -3781 bytes (-7.93%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 45689 bytes -2004 bytes (-4.20%)
ZSTD (Wikipedia) zstd zstd -19 46215 bytes -1478 bytes (-3.10%)

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