Choose a version:
46% The original file has 309018 bytes (301.8k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 143034 bytes (139.7k, 46%).

After GZIP compression these minified files vary in size:
Boot
  56242 bytes (54.9k)
CDN, direct link
Baidu
  49264 bytes (48.1k)
CDN, direct link
cdnjs
  49255 bytes (48.1k)
CDN, direct link
gzip -6 (default)
  48877 bytes (47.7k)
local copy
unpkg
  48866 bytes (47.7k)
CDN, direct link
cdnhttps
  48829 bytes (47.7k)
CDN, direct link
gzip -9
  48694 bytes (47.6k)
local copy
libdeflate -12
  47096 bytes (46.0k)
local copy
7zip -mx=9 -tgzip
  47090 bytes (46.0k)
local copy
pigz -11 -n
  46875 bytes (45.8k)
local copy
kzip -s0 -rn -b6
  46855 bytes (45.8k)
local copy
Zopfli
  46770 bytes (45.7k)
local copy
Zopfli (defluff)
  46767 bytes (45.7k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/d3/d3-3.2.7.min.js

You will automatically get the smallest D3 3.2.7 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 2059 bytes by using my D3 3.2.7 Zopfli version instead of the best available CDN (4.40% smaller than cdnhttps, 46770 vs. 48829 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 --mls8 --bsr16 --lazy --ohh

(found December 21, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 8  --mls8
block splitting recursion 16  --bsr16
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 3 more bytes (46767 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/v3.2.7/d3.min.js --location | md5sum
c9510c6a3559e7ff9706d45575e84779  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-3.2.7.min.zopfli.js.gz | md5sum
c9510c6a3559e7ff9706d45575e84779  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/mbostock/d3/v3.2.7/d3.min.js --location | sha1sum
fb19d9b2c37ab0d14b4ae9d96ea10c42116eaff7  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-3.2.7.min.zopfli.js.gz | sha1sum
fb19d9b2c37ab0d14b4ae9d96ea10c42116eaff7  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 56242 bytes c9510c6a3559e7ff9706d45575e84779 (invalid)
cdnjs 49255 bytes c9510c6a3559e7ff9706d45575e84779 (invalid)
unpkg 48866 bytes c9510c6a3559e7ff9706d45575e84779 July 11, 2016 @ 16:32
cdnhttps 48829 bytes c9510c6a3559e7ff9706d45575e84779 December 24, 2015 @ 07:33

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
Baidu 49264 bytes 5fe9841dccfed7ee99ef2d76ace8a2bf 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
46770 bytes -6 bytes zopfli --i100000 --mls8 --bsr16 --lazy --ohh December 21, 2015 @ 15:56
46776 bytes -6 bytes zopfli --i10000 --mls8 --bsr16 --lazy --ohh October 14, 2015 @ 08:34
46782 bytes -11 bytes zopfli --i1000 --mls8 --bsr16 --lazy --ohh September 20, 2015 @ 02:03
46793 bytes zopfli --i100 --mls8 --bsr16 --lazy --ohh September 18, 2015 @ 19:56

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

Most recent activity on March 1, 2017 @ 03:41.

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
46924 46877 46922 46924 46928 46892 46891 46920 46842 47012 47066 47050 47061 46830 47056
46853 46854 46872 46871 46807 46815 46842 46839 46809 46805 46902 46820 47041 46809 47033
46906 46813 46832 46823 46845 46833 46855 46829 46814 46804 46805 46775 47039 46857 46852
46878 46825 46810 46821 46884 46803 46834 47062 46808 46833 47063 46872 47039 46903 46905
46882 46884 46827 46819 46814 46809 46868 46827 46846 46806 46813 46780 47042 46912 46900
46883 46885 46863 46818 46841 46844 46839 46858 46830 46804 46807 46792 47055 46873 46844
46868 46884 46813 46836 46852 46792 46819 46836 46810 46795 46972 46953 47044 46875 47069
46875 46882 46799 46866 46792 46844 46851 46839 46807 46804 46809 46840 47044 46849 46826
46873 46885 46848 46829 46830 46816 46818 46801 46801 46806 46809 46783 47045 46862 46802
46803 46877 46844 46816 46854 46814 46834 46825 46803 46803 46805 46797 47056 46847 46787
46868 46856 46802 46817 46800 46795 46794 46794 46805 46799 46803 46781 47046 46812 46880
46860 46827 46815 46803 46834 46847 46816 46837 46802 46810 46975 46975 47044 46837 46882
46880 46858 46770 46853 46863 46846 46842 46831 46806 46806 46791 46797 47044 46812 46857
46849 46853 46804 46820 46815 46798 46841 46829 46805 46799 46807 46797 47044 46811 46788
46868 46890 46824 46806 46803 46800 46840 46841 46804 46809 46807 46802 47046 46847 46835
46888 46858 46821 46864 46821 46816 46883 46827 46813 46809 46810 46802 47044 46815 46849
46852 46868 46802 46851 46819 46821 46815 46826 46805 46802 46808 46785 47044 46821 46853
46848 46860 46860 46804 46806 46797 46841 46804 46799 46808 46977 46786 47040 46812 46840
46889 46880 46825 46801 46851 46844 46840 46847 46814 46802 46806 46780 47046 46848 46825
46873 46816 46858 46819 46820 46817 46801 46848 46802 46803 46898 46802 47044 46858 46862
46867 46881 46827 46814 46802 46801 46849 46831 46802 46801 46807 46801 47042 46867 46827
46874 46875 46818 46817 46872 46837 46844 46838 46860 46809 46902 46776 47044 46877 46803
46848 46870 46807 46826 46848 46816 46823 46830 46806 46807 46806 46785 47046 46857 46801

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 46793 bytes 100%
1,000 46782 bytes -11 bytes 100%
10,000 46776 bytes -6 bytes 100%
100,000 46770 bytes -6 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
47000 bytes +230 bytes (+0.49%) +145 bytes
47091 bytes +321 bytes (+0.69%) +236 bytes
47086 bytes +316 bytes (+0.68%) +231 bytes
47001 bytes +231 bytes (+0.49%) +146 bytes
47003 bytes +233 bytes (+0.50%) +148 bytes
46931 bytes +161 bytes (+0.34%) +76 bytes
46855 bytes +85 bytes (+0.18%)
46884 bytes +114 bytes (+0.24%) +29 bytes
46891 bytes +121 bytes (+0.26%) +36 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 37502 bytes -9268 bytes (-19.82%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 39687 bytes -7083 bytes (-15.14%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 40292 bytes -6478 bytes (-13.85%)
Brotli (Wikipedia) brotli brotli -q 11 42305 bytes -4465 bytes (-9.55%)
LZMA2 (Wikipedia) xz xz -9 43004 bytes -3766 bytes (-8.05%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 44842 bytes -1928 bytes (-4.12%)
ZSTD (Wikipedia) zstd zstd -19 45281 bytes -1489 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