Choose a version:
48% The original file has 505558 bytes (493.7k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 241979 bytes (236.3k, 48%).

After GZIP compression these minified files vary in size:
Boot
  79811 bytes (77.9k)
CDN
cdnjs
  79811 bytes (77.9k)
CDN
gzip -6 (default)
  79098 bytes (77.2k)
local copy
gzip -9
  78800 bytes (77.0k)
local copy
libdeflate -12
  75563 bytes (73.8k)
local copy
7zip -mx=9 -tgzip
  75142 bytes (73.4k)
local copy
kzip -s0 -rn -b8
  74903 bytes (73.1k)
local copy
pigz -11 -n
  74722 bytes (73.0k)
local copy
Zopfli
  74630 bytes (72.9k)
local copy
Zopfli (defluff)
  74629 bytes (72.9k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/d3/d3-5.8.1.min.js (or via HTTPS)

You will automatically get the smallest D3 5.8.1 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 5181 bytes by using my D3 5.8.1 Zopfli version instead of the best available CDN (6.94% smaller than cdnjs, 74630 vs. 79811 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 --i1000000 --mb8 --mls8192 --bsr20 --lazy --ohh

(found February 6, 2019)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 8192  --mls8192
block splitting recursion 20  --bsr20
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 (74629 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/v5.8.1/d3.zip --location | md5sum
828fab9af3dad9906051ab330e6db9f7  -
curl --silent --compressed https://minime.stephan-brumme.com/files/d3/d3-5.8.1.min.zopfli.js.gz | md5sum
828fab9af3dad9906051ab330e6db9f7  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/mbostock/d3/v5.8.1/d3.zip --location | sha1sum
f50ecc6f5d52dfb26f68f669553802e18c5defa7  -
curl --silent --compressed https://minime.stephan-brumme.com/files/d3/d3-5.8.1.min.zopfli.js.gz | sha1sum
f50ecc6f5d52dfb26f68f669553802e18c5defa7  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 79811 bytes 828fab9af3dad9906051ab330e6db9f7 February 4, 2019 @ 22:15
cdnjs 79811 bytes 828fab9af3dad9906051ab330e6db9f7 February 4, 2019 @ 22:15

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

Other Versions

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

5.9.2, 5.9.1, 5.9.0, 5.8.2, 5.8.1, 5.8.0, 5.7.0, 5.6.0, 5.5.0, 5.4.0, 5.3.0, 5.2.0, 5.1.0, 5.0.1, 5.0.0,
4.13.0, 4.12.2, 4.12.1, 4.12.0, 4.11.0, 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
74630 bytes -5 bytes zopfli --i1000000 --mls8192 --bsr20 --lazy --ohh February 6, 2019 @ 06:56
74635 bytes -4 bytes zopfli --i100000 --mls8192 --bsr20 --lazy --ohh February 5, 2019 @ 19:52
74639 bytes -8 bytes zopfli --i10000 --mls8192 --bsr20 --lazy --ohh February 5, 2019 @ 15:34
74647 bytes -3 bytes zopfli --i1000 --mls8192 --bsr13 --lazy --ohh February 5, 2019 @ 13:50
74650 bytes -22 bytes zopfli --i1000 --mls8192 --bsr10 --lazy --ohh February 5, 2019 @ 13:48
74672 bytes -2 bytes zopfli --i1000 --mls16384 --bsr17 --lazy --ohh February 5, 2019 @ 13:47
74674 bytes zopfli --i100 --mls8192 --bsr13 --lazy --ohh February 5, 2019 @ 13:34

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

Most recent activity on February 6, 2019 @ 22:04.

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, 100,000 or 1,000,000.
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
75051 75051 74876 75076 75075 75084 74899 75069 74899 74870 75069 74905 74914 74836 75054
74751 74988 74924 75073 74766 74765 75077 75078 75292 74733 74734 74783 74822 74808 74858
74893 74695 74704 74701 74683 74688 74690 74693 74672 74708 74820 74704 74722 75043 74827
74996 74903 74685 74910 74881 74867 74689 74697 74688 74704 74683 74687 74691 74884 74804
74884 74682 74965 74739 74733 74957 74966 74961 74879 74740 74792 74816 74767 74965 74832
74893 74680 74695 74703 74699 74874 74695 74692 74876 74682 74683 74690 74684 74685 74675
74686 74688 74678 74687 74677 74692 74693 74693 74696 74693 74687 74686 74636 74822 74825
74686 74874 74683 74739 74684 74684 74693 74871 74875 74697 74684 74686 74752 74667 74802
74993 74873 74869 74681 74872 74874 74684 74696 74693 74706 74713 74685 74670 74763 74866
74877 74868 74679 74875 74869 74868 74883 74884 74863 74688 74690 74685 74630 74752 74652
74997 74880 74875 74873 74865 74896 74678 74879 74976 74738 74687 74687 74684 74856 74869
75003 74877 74882 74873 74880 74694 74882 74883 74890 74685 74713 74706 74687 75048 74800
75002 74682 74681 74684 74683 74873 74689 74699 74684 74685 74687 74665 74684 74661 74804
74681 74685 74738 74736 74682 74726 74756 74692 74691 74690 74707 74689 74863 74664 74759
74681 74869 74679 74683 74875 74686 74877 74882 74682 74686 74687 74687 74680 74835 74801
75001 74879 74871 74876 74882 74683 74670 74692 74880 74689 74690 74688 74687 74874 74827
74872 74872 74679 74875 74872 74872 74882 74886 74973 74737 74682 74685 74630 74850 74798
74869 74876 74868 74873 74872 74684 74884 74879 74878 74695 74801 74685 74682 74763 74809
75004 74879 74981 74874 74875 74874 74879 74882 74977 74685 74684 74693 74681 74829 74671
74878 74877 74981 74875 74869 74681 74694 74696 74693 74686 74683 74689 74681 74873 74811
74995 74875 74981 74677 74873 74685 74886 74690 74685 74682 74692 74685 74687 74811 74767
74997 74874 74985 74875 74870 74679 74884 74880 74878 74694 74688 74688 74830 74984 74833
74993 74879 74871 74873 74875 74873 74878 74882 74692 74684 74686 74687 74862 74878 74758

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 74674 bytes 100%
1,000 74647 bytes -27 bytes 100%
10,000 74639 bytes -8 bytes 100%
100,000 74634 bytes -5 bytes 0.87%
1,000,000 74630 bytes -4 bytes 0.58%
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
75055 bytes +425 bytes (+0.57%) +152 bytes
76420 bytes +1790 bytes (+2.40%) +1517 bytes
76304 bytes +1674 bytes (+2.24%) +1401 bytes
75068 bytes +438 bytes (+0.59%) +165 bytes
75085 bytes +455 bytes (+0.61%) +182 bytes
75055 bytes +425 bytes (+0.57%) +152 bytes
75085 bytes +455 bytes (+0.61%) +182 bytes
75092 bytes +462 bytes (+0.62%) +189 bytes
74903 bytes +273 bytes (+0.37%)

Non-DEFLATE Algorithms

Archivers based on completely different compression algorithms often produce superior results.
Unfortunately, browsers only support gzip compression at the moment.
However, support for Brotli is constantly growing - but your browser doesn't support it.
Algorithm Program Parameters Size Compared To Best Zopfli
ZPAQ (Wikipedia) zpaq zpaq -method 69 58825 bytes -15805 bytes (-21.18%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 65618 bytes -9012 bytes (-12.08%)
LZMA2 (Wikipedia) xz xz -9 66420 bytes -8210 bytes (-11.00%)
Brotli (Wikipedia) brotli brotli -q 11 66644 bytes -7986 bytes (-10.70%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 68328 bytes -6302 bytes (-8.44%)
Zstandard (Wikipedia) zstd zstd -19 71817 bytes -2813 bytes (-3.77%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 74443 bytes -187 bytes (-0.25%)

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 2019.
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