Choose a version:
47% The original file has 450571 bytes (440.0k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 213917 bytes (208.9k, 47%).

After GZIP compression these minified files vary in size:
Boot
  82014 bytes (80.1k)
CDN, direct link
cdnjs
  72545 bytes (70.8k)
CDN, direct link
cdnhttps
  72377 bytes (70.7k)
CDN, direct link
gzip -6 (default)
  72014 bytes (70.3k)
local copy
jsdelivr
  71925 bytes (70.2k)
CDN, direct link
gzip -9
  71773 bytes (70.1k)
local copy
libdeflate -12
  68978 bytes (67.4k)
local copy
7zip -mx=9 -tgzip
  68689 bytes (67.1k)
local copy
kzip -s0 -rn -b0
  68220 bytes (66.6k)
local copy
pigz -11 -n
  68204 bytes (66.6k)
local copy
Zopfli
  68091 bytes (66.5k)
local copy
Zopfli (defluff)
  68088 bytes (66.5k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/d3/d3-4.4.0.min.js

You will automatically get the smallest D3 4.4.0 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 3834 bytes by using my D3 4.4.0 Zopfli version instead of the best available CDN (5.63% smaller than jsdelivr, 68091 vs. 71925 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 --mls32768 --bsr17 --lazy --ohh

(found November 25, 2016)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 32768  --mls32768
block splitting recursion 17  --bsr17
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 (68088 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/v4.4.0/d3.zip --location | md5sum
dac99cdafcae16ea05f91f4f0070d89d  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-4.4.0.min.zopfli.js.gz | md5sum
dac99cdafcae16ea05f91f4f0070d89d  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/mbostock/d3/v4.4.0/d3.zip --location | sha1sum
73d26173760b4e6cf8712dfb2328c5230d5230b1  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-4.4.0.min.zopfli.js.gz | sha1sum
73d26173760b4e6cf8712dfb2328c5230d5230b1  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 82014 bytes dac99cdafcae16ea05f91f4f0070d89d November 23, 2016 @ 05:55
cdnjs 72545 bytes dac99cdafcae16ea05f91f4f0070d89d November 23, 2016 @ 02:47
cdnhttps 72377 bytes dac99cdafcae16ea05f91f4f0070d89d November 24, 2016 @ 16:40
jsdelivr 71925 bytes dac99cdafcae16ea05f91f4f0070d89d January 4, 2017 @ 11:34

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
68091 bytes -5 bytes zopfli --i1000000 --mls32768 --bsr17 --lazy --ohh November 25, 2016 @ 00:39
68096 bytes -2 bytes zopfli --i100000 --mls32768 --bsr17 --lazy --ohh November 23, 2016 @ 16:35
68098 bytes -8 bytes zopfli --i10000 --mls32768 --bsr17 --lazy --ohh November 23, 2016 @ 11:42
68106 bytes -17 bytes zopfli --i1000 --mls32768 --bsr17 --lazy --ohh November 23, 2016 @ 11:15
68123 bytes zopfli --i100 --mls32768 --bsr17 --lazy --ohh November 23, 2016 @ 10:50

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

Most recent activity on January 25, 2017 @ 15:26.

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
68326 68309 68412 68400 68396 68398 68394 68398 68437 68398 68405 68483 68605 68600 68420
68242 68250 68362 68117 68273 68110 68132 68142 68119 68188 68153 68217 68267 68218 68361
68232 68226 68128 68131 68946 68936 68940 68250 68261 68327 68249 68277 68280 68948 68298
68242 68279 68938 68932 68931 68944 68939 68238 68236 68243 68236 68239 68261 68948 68297
68260 68329 68220 68932 68935 68235 68924 68285 68221 68217 68238 68226 68237 68286 68290
68223 68230 68289 68924 68922 68919 68231 68247 68210 68216 68217 68250 68292 68965 68970
68235 68926 68935 68938 68228 68919 68223 68239 68223 68229 68217 68240 68195 68238 68287
68223 68937 68918 68938 68923 68924 68936 68236 68227 68213 68239 68224 68225 68222 68102
68245 68235 68240 68922 68930 68238 68920 68209 68216 68218 68232 68246 68948 68222 68281
68228 68931 68265 68923 68935 68920 68922 68243 68236 68212 68240 68250 68233 68948 68281
68929 68936 68936 68923 68923 68928 68916 68215 68226 68218 68216 68217 68228 68250 68277
68921 68930 68229 68923 68929 68922 68924 68231 68217 68218 68234 68223 68267 68936 68273
68232 68929 68936 68928 68929 68911 68214 68216 68212 68217 68216 68219 68226 68931 68285
68931 68216 68262 68929 68933 68931 68914 68228 68214 68210 68216 68222 68229 68952 68091
68250 68268 68229 68920 68933 68939 68927 68221 68219 68224 68240 68246 68255 68236 68277
68930 68237 68234 68923 68923 68925 68226 68247 68207 68220 68218 68217 68258 68950 68261
68215 68228 68228 68923 68933 68928 68937 68227 68210 68206 68221 68230 68272 68227 68283
68222 68231 68936 68939 68929 68931 68936 68245 68211 68215 68201 68923 68195 68245 68282
68218 68229 68941 68930 68923 68932 68936 68228 68212 68215 68226 68221 68210 68948 68297
68211 68930 68274 68923 68920 68916 68229 68232 68212 68218 68209 68223 68210 68937 68277
68229 68237 68938 68937 68927 68231 68916 68219 68213 68927 68924 68920 68242 68285 68271
68913 68934 68937 68910 68924 68931 68208 68218 68216 68217 68229 68253 68238 68940 68276
68259 68222 68930 68925 68934 68909 68239 68211 68214 68207 68245 68249 68289 68281 68278

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 68123 bytes 100%
1,000 68106 bytes -17 bytes 100%
10,000 68098 bytes -8 bytes 100%
100,000 68096 bytes -2 bytes 2.61%
1,000,000 68091 bytes -5 bytes 0.29%
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
68220 bytes +129 bytes (+0.19%)
69665 bytes +1574 bytes (+2.31%) +1445 bytes
69531 bytes +1440 bytes (+2.11%) +1311 bytes
69152 bytes +1061 bytes (+1.56%) +932 bytes
68463 bytes +372 bytes (+0.55%) +243 bytes
68457 bytes +366 bytes (+0.54%) +237 bytes
68358 bytes +267 bytes (+0.39%) +138 bytes
68227 bytes +136 bytes (+0.20%) +7 bytes
68231 bytes +140 bytes (+0.21%) +11 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 53861 bytes -14230 bytes (-20.90%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 59882 bytes -8209 bytes (-12.06%)
LZMA2 (Wikipedia) xz xz -9 60696 bytes -7395 bytes (-10.86%)
Brotli (Wikipedia) brotli brotli -q 11 60868 bytes -7223 bytes (-10.61%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 62337 bytes -5754 bytes (-8.45%)
ZSTD (Wikipedia) zstd zstd -19 66049 bytes -2042 bytes (-3.00%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 67308 bytes -783 bytes (-1.15%)

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