Choose a version:
47% The original file has 292355 bytes (285.5k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 137048 bytes (133.8k, 47%).

After GZIP compression these minified files vary in size:
Boot
  53414 bytes (52.2k)
CDN, direct link
Baidu
  46600 bytes (45.5k)
CDN, direct link
cdnjs
  46589 bytes (45.5k)
CDN, direct link
gzip -6 (default)
  46302 bytes (45.2k)
local copy
cdnhttps
  46256 bytes (45.2k)
CDN, direct link
unpkg
  46172 bytes (45.1k)
CDN, direct link
gzip -9
  46121 bytes (45.0k)
local copy
7zip -mx=9 -tgzip
  44600 bytes (43.6k)
local copy
libdeflate -12
  44584 bytes (43.5k)
local copy
kzip -s0 -rn -b7
  44515 bytes (43.5k)
local copy
pigz -11 -n
  44425 bytes (43.4k)
local copy
Zopfli
  44301 bytes (43.3k)
local copy
Zopfli (defluff)
  44298 bytes (43.3k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/d3/d3-3.1.1.min.js

You will automatically get the smallest D3 3.1.1 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 1871 bytes by using my D3 3.1.1 Zopfli version instead of the best available CDN (4.22% smaller than unpkg, 44301 vs. 46172 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 --bsr25 --lazy --ohh

(found December 21, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 8  --mls8
block splitting recursion 25  --bsr25
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 (44298 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/v3.1.1/d3.min.js --location | md5sum
07ba43024d6f0e171498e4338e4746a5  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-3.1.1.min.zopfli.js.gz | md5sum
07ba43024d6f0e171498e4338e4746a5  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/mbostock/d3/v3.1.1/d3.min.js --location | sha1sum
e2a68eb4c7bb2c3f4e949865bf9234fb57d2d600  -
curl --silent --compressed http://minime.stephan-brumme.com/files/d3/d3-3.1.1.min.zopfli.js.gz | sha1sum
e2a68eb4c7bb2c3f4e949865bf9234fb57d2d600  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Boot 53414 bytes 07ba43024d6f0e171498e4338e4746a5 (invalid)
cdnjs 46589 bytes 07ba43024d6f0e171498e4338e4746a5 (invalid)
cdnhttps 46256 bytes 07ba43024d6f0e171498e4338e4746a5 December 24, 2015 @ 07:33
unpkg 46172 bytes 07ba43024d6f0e171498e4338e4746a5 July 11, 2016 @ 16:32

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
Baidu 46600 bytes 3131202a2dfdd23d51836ba645e25e67 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:

4.10.0,
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
44301 bytes -6 bytes zopfli --i100000 --mls8 --bsr25 --lazy --ohh December 21, 2015 @ 12:00
44307 bytes -7 bytes zopfli --i10000 --mls8 --bsr25 --lazy --ohh September 23, 2015 @ 20:38
44314 bytes -2 bytes zopfli --i1000 --mls8 --bsr25 --lazy --ohh September 23, 2015 @ 19:08
44316 bytes -8 bytes zopfli --i1000 --mls128 --bsr20 --lazy --ohh September 20, 2015 @ 14:54
44324 bytes zopfli --i100 --mls256 --bsr12 --lazy --ohh September 18, 2015 @ 19:52

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

Most recent activity on March 3, 2017 @ 10:31.

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
44499 44494 44493 44493 44489 44491 44494 44349 44492 44471 44479 44492 44499 44500 44515
44465 44461 44484 44490 44407 44382 44390 44377 44467 44413 44401 44402 44502 44381 44494
44425 44357 44407 44413 44415 44370 44383 44330 44352 44348 44380 44410 44523 44424 44518
44493 44310 44388 44422 44378 44402 44312 44445 44405 44353 44382 44486 44493 44509 44397
44382 44387 44483 44484 44444 44379 44368 44374 44354 44376 44376 44384 44514 44511 44500
44432 44381 44411 44428 44391 44375 44368 44461 44502 44504 44384 44334 44501 44511 44497
44494 44404 44423 44403 44402 44398 44353 44468 44460 44335 44373 44349 44506 44389 44473
44406 44485 44376 44410 44488 44385 44333 44364 44376 44347 44379 44403 44507 44509 44497
44417 44406 44412 44397 44378 44337 44353 44310 44380 44343 44380 44369 44514 44404 44506
44388 44484 44371 44397 44393 44398 44355 44356 44373 44352 44383 44404 44500 44509 44474
44418 44395 44400 44400 44392 44373 44367 44441 44456 44333 44370 44390 44501 44404 44503
44487 44397 44485 44400 44405 44370 44331 44467 44450 44351 44379 44339 44390 44510 44474
44386 44408 44359 44400 44479 44379 44345 44444 44459 44340 44387 44389 44503 44513 44511
44381 44409 44413 44478 44398 44384 44375 44397 44394 44338 44381 44496 44512 44508 44484
44374 44383 44379 44379 44403 44384 44376 44335 44376 44333 44384 44336 44507 44411 44510
44414 44394 44403 44413 44385 44380 44358 44341 44330 44355 44384 44389 44515 44377 44499
44381 44386 44382 44375 44401 44383 44310 44443 44456 44374 44376 44440 44509 44379 44407
44418 44389 44352 44402 44364 44380 44373 44447 44469 44339 44383 44410 44514 44375 44396
44492 44400 44451 44486 44485 44386 44355 44392 44379 44346 44383 44486 44513 44509 44502
44386 44369 44416 44396 44389 44383 44351 44315 44345 44339 44383 44343 44515 44401 44508
44418 44385 44301 44478 44485 44374 44347 44443 44462 44342 44381 44477 44508 44509 44493
44315 44390 44430 44493 44485 44379 44377 44444 44455 44338 44379 44348 44511 44509 44507
44382 44384 44405 44406 44382 44373 44389 44465 44455 44333 44388 44345 44504 44508 44510

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 44323 bytes 100%
1,000 44314 bytes -9 bytes 100%
10,000 44307 bytes -7 bytes 100%
100,000 44301 bytes -6 bytes 0.29%
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
44532 bytes +231 bytes (+0.52%) +17 bytes
44536 bytes +235 bytes (+0.53%) +21 bytes
44532 bytes +231 bytes (+0.52%) +17 bytes
44543 bytes +242 bytes (+0.55%) +28 bytes
44582 bytes +281 bytes (+0.63%) +67 bytes
44592 bytes +291 bytes (+0.66%) +77 bytes
44567 bytes +266 bytes (+0.60%) +52 bytes
44515 bytes +214 bytes (+0.48%)
44516 bytes +215 bytes (+0.49%) +1 byte

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 35581 bytes -8720 bytes (-19.68%)
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 37671 bytes -6630 bytes (-14.97%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 38224 bytes -6077 bytes (-13.72%)
Brotli (Wikipedia) brotli brotli -q 11 40108 bytes -4193 bytes (-9.46%)
LZMA2 (Wikipedia) xz xz -9 40864 bytes -3437 bytes (-7.76%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 42615 bytes -1686 bytes (-3.81%)
ZSTD (Wikipedia) zstd zstd -19 42776 bytes -1525 bytes (-3.44%)

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