Choose a version:
46% The original file has 314783 bytes (307.4k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 144408 bytes (141.0k, 46%).

After GZIP compression these minified files vary in size:
Boot
  57153 bytes (55.8k)
CDN, direct link
Baidu
  50107 bytes (48.9k)
CDN, direct link
cdnjs
  50097 bytes (48.9k)
CDN, direct link
unpkg
  49718 bytes (48.6k)
CDN, direct link
gzip -6 (default)
  49695 bytes (48.5k)
local copy
cdnhttps
  49684 bytes (48.5k)
CDN, direct link
gzip -9
  49527 bytes (48.4k)
local copy
libdeflate -12
  47969 bytes (46.8k)
local copy
7zip -mx=9 -tgzip
  47931 bytes (46.8k)
local copy
pigz -11 -n
  47695 bytes (46.6k)
local copy
kzip -s0 -rn -b6
  47675 bytes (46.6k)
local copy
Zopfli
  47587 bytes (46.5k)
local copy
Zopfli (defluff)
  47586 bytes (46.5k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/d3/d3-3.3.1.min.js

You will automatically get the smallest D3 3.3.1 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 2097 bytes by using my D3 3.3.1 Zopfli version instead of the best available CDN (4.41% smaller than cdnhttps, 47587 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 --mls16384 --bsr15 --lazy --ohh

(found December 21, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 16384  --mls16384
block splitting recursion 15  --bsr15
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 (47586 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/v3.3.1/d3.min.js --location | md5sum
822f50b3b8f65dc7ce8e59c92186ef81  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-3.3.1.min.zopfli.js.gz | md5sum
822f50b3b8f65dc7ce8e59c92186ef81  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/mbostock/d3/v3.3.1/d3.min.js --location | sha1sum
b5bf8e6b4b3c858c35c7434157961da8f033526f  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-3.3.1.min.zopfli.js.gz | sha1sum
b5bf8e6b4b3c858c35c7434157961da8f033526f  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 57153 bytes 822f50b3b8f65dc7ce8e59c92186ef81 (invalid)
cdnjs 50097 bytes 822f50b3b8f65dc7ce8e59c92186ef81 (invalid)
unpkg 49718 bytes 822f50b3b8f65dc7ce8e59c92186ef81 July 11, 2016 @ 16:31
cdnhttps 49684 bytes 822f50b3b8f65dc7ce8e59c92186ef81 December 24, 2015 @ 07:33

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
Baidu 50107 bytes 12883804093bbce1cab9701327d9e43d 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
47587 bytes -4 bytes zopfli --i100000 --mls16384 --bsr15 --lazy --ohh December 21, 2015 @ 16:45
47591 bytes -1 byte zopfli --i10000 --mls16384 --bsr15 --lazy --ohh November 23, 2015 @ 17:47
47592 bytes -6 bytes zopfli --i10000 --mls16384 --bsr30 --lazy --ohh October 14, 2015 @ 04:52
47598 bytes -7 bytes zopfli --i1000 --mls16384 --bsr15 --lazy --ohh September 20, 2015 @ 00:25
47605 bytes zopfli --i100 --mls16384 --bsr15 --lazy --ohh September 18, 2015 @ 22:19

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 @ 23:29.

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 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
47673 47695 47748 47699 47719 47746 47736 47715 47734 47740 47869 47841 47869 47746 47873
47718 47662 47660 47620 47632 47696 47632 47739 47658 47638 47866 47637 47864 47724 47864
47644 47702 47620 47623 47620 47620 47660 47730 47696 47630 47628 47614 47839 47688 47722
47614 47710 47688 47614 47643 47623 47685 47733 47712 47856 47624 47616 47850 47857 47705
47680 47615 47628 47633 47640 47658 47650 47646 47725 47726 47723 47716 47848 47711 47720
47628 47638 47618 47615 47623 47636 47654 47702 47632 47633 47625 47704 47851 47708 47713
47615 47626 47617 47628 47655 47615 47613 47625 47631 47622 47863 47780 47847 47686 47714
47621 47602 47605 47617 47614 47614 47681 47629 47653 47659 47625 47656 47845 47762 47705
47639 47598 47616 47620 47623 47612 47625 47627 47676 47664 47623 47623 47849 47599 47716
47617 47676 47617 47620 47622 47602 47615 47672 47634 47644 47628 47671 47840 47699 47704
47633 47646 47616 47619 47636 47630 47693 47629 47628 47627 47631 47706 47864 47601 47709
47639 47638 47616 47623 47619 47615 47689 47625 47680 47614 47624 47626 47849 47587 47699
47634 47606 47616 47617 47618 47622 47682 47633 47677 47620 47623 47789 47849 47684 47708
47618 47597 47616 47617 47619 47624 47620 47698 47633 47626 47626 47632 47848 47601 47708
47619 47601 47618 47657 47617 47618 47649 47627 47628 47637 47627 47629 47849 47686 47714
47629 47662 47615 47620 47623 47617 47634 47696 47626 47628 47628 47618 47850 47857 47708
47654 47661 47619 47614 47643 47624 47620 47699 47633 47651 47628 47680 47850 47715 47707
47665 47606 47617 47620 47622 47601 47657 47687 47632 47623 47728 47764 47849 47684 47714
47655 47659 47619 47626 47626 47616 47688 47686 47629 47632 47621 47779 47849 47602 47714
47636 47658 47618 47610 47622 47626 47620 47691 47671 47632 47629 47690 47853 47587 47709
47640 47658 47604 47617 47637 47615 47685 47625 47635 47629 47625 47691 47849 47719 47710
47643 47684 47624 47626 47622 47616 47616 47689 47635 47631 47625 47693 47838 47587 47855
47637 47607 47623 47662 47618 47620 47647 47637 47631 47631 47623 47686 47850 47602 47716

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 47605 bytes 100%
1,000 47598 bytes -7 bytes 100%
10,000 47591 bytes -7 bytes 100%
100,000 47587 bytes -4 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
47890 bytes +303 bytes (+0.64%) +215 bytes
47890 bytes +303 bytes (+0.64%) +215 bytes
47896 bytes +309 bytes (+0.65%) +221 bytes
47811 bytes +224 bytes (+0.47%) +136 bytes
47819 bytes +232 bytes (+0.49%) +144 bytes
47684 bytes +97 bytes (+0.20%) +9 bytes
47675 bytes +88 bytes (+0.18%)
47695 bytes +108 bytes (+0.23%) +20 bytes
47702 bytes +115 bytes (+0.24%) +27 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 38181 bytes -9406 bytes (-19.77%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 40383 bytes -7204 bytes (-15.14%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 41068 bytes -6519 bytes (-13.70%)
Brotli (Wikipedia) brotli brotli -q 11 43064 bytes -4523 bytes (-9.50%)
LZMA2 (Wikipedia) xz xz -9 43788 bytes -3799 bytes (-7.98%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 45580 bytes -2007 bytes (-4.22%)
ZSTD (Wikipedia) zstd zstd -19 46074 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