Choose a version:
45% The original file has 325740 bytes (318.1k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 146611 bytes (143.2k, 45%).

After GZIP compression these minified files vary in size:
Boot
  58369 bytes (57.0k)
CDN, direct link
Baidu
  51377 bytes (50.2k)
CDN, direct link
cdnjs
  51370 bytes (50.2k)
CDN, direct link
unpkg
  51027 bytes (49.8k)
CDN, direct link
gzip -6 (default)
  50968 bytes (49.8k)
local copy
cdnhttps
  50928 bytes (49.7k)
CDN, direct link
gzip -9
  50792 bytes (49.6k)
local copy
libdeflate -12
  49149 bytes (48.0k)
local copy
7zip -mx=9 -tgzip
  49102 bytes (48.0k)
local copy
pigz -11 -n
  48889 bytes (47.7k)
local copy
kzip -s0 -rn -b7
  48880 bytes (47.7k)
local copy
Zopfli
  48764 bytes (47.6k)
local copy
Zopfli (defluff)
  48763 bytes (47.6k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/d3/d3-3.3.12.min.js

You will automatically get the smallest D3 3.3.12 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 2164 bytes by using my D3 3.3.12 Zopfli version instead of the best available CDN (4.44% smaller than cdnhttps, 48764 vs. 50928 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 --mls4 --bsr19 --lazy --ohh

(found December 22, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 4  --mls4
block splitting recursion 19  --bsr19
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 (48763 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/v3.3.12/d3.min.js --location | md5sum
ae6bfe01bd8115848ab77a508de9f108  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-3.3.12.min.zopfli.js.gz | md5sum
ae6bfe01bd8115848ab77a508de9f108  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/mbostock/d3/v3.3.12/d3.min.js --location | sha1sum
3d01302430a28c3c5694c2c0ad12134a155827aa  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-3.3.12.min.zopfli.js.gz | sha1sum
3d01302430a28c3c5694c2c0ad12134a155827aa  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 58369 bytes ae6bfe01bd8115848ab77a508de9f108 (invalid)
cdnjs 51370 bytes ae6bfe01bd8115848ab77a508de9f108 (invalid)
unpkg 51027 bytes ae6bfe01bd8115848ab77a508de9f108 July 11, 2016 @ 16:31
cdnhttps 50928 bytes ae6bfe01bd8115848ab77a508de9f108 December 24, 2015 @ 07:33

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
Baidu 51377 bytes 6c046cb238d2fcf9d20533641918d194 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:

4.9.1, 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
48764 bytes -4 bytes zopfli --i100000 --mls4 --bsr19 --lazy --ohh December 22, 2015 @ 10:19
48768 bytes -2 bytes zopfli --i10000 --mls4 --bsr19 --lazy --ohh November 23, 2015 @ 17:53
48770 bytes -7 bytes zopfli --i10000 --mls4 --bsr11 --lazy --ohh October 14, 2015 @ 04:48
48777 bytes -5 bytes zopfli --i1000 --mls4 --bsr19 --lazy --ohh September 21, 2015 @ 21:12
48782 bytes -12 bytes zopfli --i1000 --mls4 --bsr11 --lazy --ohh September 21, 2015 @ 20:42
48794 bytes -14 bytes zopfli --i1000 --mls8 --bsr12 --lazy --ohh September 19, 2015 @ 15:06
48808 bytes zopfli --i100 --mls8 --bsr12 --lazy --ohh September 18, 2015 @ 21:08

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

Most recent activity on February 25, 2017 @ 22:32.

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 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
49050 49047 48901 48949 48919 48886 48938 48931 48893 48930 49055 49034 49055 49057 49060
48862 48864 48944 48945 48840 48911 48896 48892 48865 48800 48806 48916 49056 49051 49061
48879 48822 48871 48821 48819 48863 48893 48861 48849 48838 48928 48795 49047 49050 49034
48830 48848 48849 48813 48816 48884 48876 48865 48889 48804 48883 48805 49050 49051 48884
48854 48792 48906 48898 48825 48818 48892 48869 48857 48806 48911 48904 49050 49053 48892
48853 48871 48862 48838 48835 48945 48897 48893 48888 48808 48903 48794 49035 49060 48890
48857 48806 48814 48828 48868 48914 48878 48866 48798 48868 48871 48977 49046 49033 48884
48831 48765 48868 48921 48974 48976 48882 48894 48889 48912 48903 48901 49026 49047 48908
48844 48786 48781 48815 48896 48883 48884 48893 48891 48800 48800 48795 49047 49059 49042
48843 48813 48866 48866 48866 48882 48896 48866 48868 48871 48797 48802 49026 49048 49040
48881 48780 48860 48824 48830 48868 48884 48854 48830 48893 48807 49050 49036 49049 49042
48835 48815 48820 48823 48826 48878 48912 48864 48863 48806 48799 48812 49046 49051 48888
48796 48812 48823 48899 48873 48899 48878 48869 48823 48804 48802 48968 49045 49045 48894
48847 48815 48788 48828 48862 48880 48890 48868 48825 48896 48872 48810 49041 49051 48889
48807 48787 48862 48826 48843 48876 48849 48863 48841 48895 48797 49053 49054 49053 49045
48808 48764 48818 48825 48832 48859 48882 48863 48863 48867 48815 49052 49045 49045 49049
48802 48805 48819 48824 48817 48882 48891 48872 48863 48808 48800 49051 49027 49047 49035
48838 48804 48817 48815 48824 48876 48894 48854 48860 48891 48903 49051 49036 49028 48880
48841 48784 48859 48821 48817 48877 48884 48868 48849 48869 48874 48960 49042 49046 49045
48799 48802 48778 48824 48822 48908 48890 48870 48851 48908 48798 49051 49056 49045 48825
48846 48782 48783 48815 48815 48884 48883 48874 48861 48899 48874 48819 49046 49061 48850
48846 48814 48779 48813 48775 48905 48876 48874 48845 48810 48798 48810 49046 49043 48864
48851 48814 48825 48820 48789 48858 48885 48870 48837 48804 48800 49051 49026 49058 49033

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 48795 bytes 100%
1,000 48777 bytes -18 bytes 100%
10,000 48768 bytes -9 bytes 100%
100,000 48764 bytes -4 bytes 0.58%
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
49012 bytes +248 bytes (+0.51%) +132 bytes
49092 bytes +328 bytes (+0.67%) +212 bytes
49094 bytes +330 bytes (+0.68%) +214 bytes
49013 bytes +249 bytes (+0.51%) +133 bytes
49024 bytes +260 bytes (+0.53%) +144 bytes
49034 bytes +270 bytes (+0.55%) +154 bytes
48941 bytes +177 bytes (+0.36%) +61 bytes
48880 bytes +116 bytes (+0.24%)
48883 bytes +119 bytes (+0.24%) +3 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 39014 bytes -9750 bytes (-19.99%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 41450 bytes -7314 bytes (-15.00%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 42171 bytes -6593 bytes (-13.52%)
Brotli (Wikipedia) brotli brotli -q 11 44175 bytes -4589 bytes (-9.41%)
LZMA2 (Wikipedia) xz xz -9 44832 bytes -3932 bytes (-8.06%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 46806 bytes -1958 bytes (-4.02%)
ZSTD (Wikipedia) zstd zstd -19 47266 bytes -1498 bytes (-3.07%)

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