Choose a version:
53% The original file has 68954 bytes (67.3k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 36868 bytes (36.0k, 53%).

After GZIP compression these minified files vary in size:
Microsoft
  12955 bytes (12.7k)
CDN, direct link
Boot
  11804 bytes (11.5k)
CDN, direct link
MaxCDN
  11804 bytes (11.5k)
CDN, direct link
jsdelivr
  11804 bytes (11.5k)
CDN, direct link
cdnjs
  9856 bytes (9.6k)
CDN, direct link
gzip -6 (default)
  9787 bytes (9.6k)
local copy
cdnhttps
  9764 bytes (9.5k)
CDN, direct link
unpkg
  9763 bytes (9.5k)
CDN, direct link
gzip -9
  9762 bytes (9.5k)
local copy
Yandex
  9743 bytes (9.5k)
CDN, direct link
libdeflate -12
  9459 bytes (9.2k)
local copy
7zip -mx=9 -tgzip
  9457 bytes (9.2k)
local copy
kzip -s0 -rn -b0
  9455 bytes (9.2k)
local copy
pigz -11 -n
  9402 bytes (9.2k)
local copy
Zopfli
  9395 bytes (9.2k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.3.6.min.js

You will automatically get the smallest Bootstrap 3.3.6 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 348 bytes by using my Bootstrap 3.3.6 Zopfli version instead of the best available CDN (3.70% smaller than Yandex, 9395 vs. 9743 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 --mls512 --bsr7 --lazy --ohh

(found November 26, 2015)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 512  --mls512
block splitting recursion 7  --bsr7
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

Verify file integrity

After decompression, my uncompressed files are identical to the original ones:

MD5:
curl --silent --compressed https://raw.githubusercontent.com/twbs/bootstrap/v3.3.6/dist/js/bootstrap.min.js --location | md5sum
c5b5b2fa19bd66ff23211d9f844e0131  -
curl --silent --compressed http://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.3.6.min.zopfli.js.gz | md5sum
c5b5b2fa19bd66ff23211d9f844e0131  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/twbs/bootstrap/v3.3.6/dist/js/bootstrap.min.js --location | sha1sum
791aa054a026bddc0de92bad6cf7a1c6e73713d5  -
curl --silent --compressed http://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.3.6.min.zopfli.js.gz | sha1sum
791aa054a026bddc0de92bad6cf7a1c6e73713d5  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Microsoft 12955 bytes c5b5b2fa19bd66ff23211d9f844e0131 December 12, 2015 @ 20:47
Boot 11804 bytes c5b5b2fa19bd66ff23211d9f844e0131 December 4, 2015 @ 08:32
MaxCDN 11804 bytes c5b5b2fa19bd66ff23211d9f844e0131 (invalid)
jsdelivr 11804 bytes c5b5b2fa19bd66ff23211d9f844e0131 November 29, 2015 @ 21:26
cdnjs 9856 bytes c5b5b2fa19bd66ff23211d9f844e0131 (invalid)
cdnhttps 9764 bytes c5b5b2fa19bd66ff23211d9f844e0131 December 24, 2015 @ 07:36
unpkg 9763 bytes c5b5b2fa19bd66ff23211d9f844e0131 July 11, 2016 @ 16:21
Yandex 9743 bytes c5b5b2fa19bd66ff23211d9f844e0131 (invalid)

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

Other Versions

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

3.3.7, 3.3.6, 3.3.5, 3.3.4, 3.3.2, 3.3.1, 3.3.0,
3.2.0,
3.1.1, 3.1.0,
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, D3, Dojo, Ember, jQuery, Knockout, lodash, React, Socket.IO, ThreeJS, UnderscoreJS and Vue.

Changelog

Best Zopfli parameters so far:
Size Improvement Parameters Found
9395 bytes -1 byte zopfli --i1000000 --mls512 --bsr7 --lazy --ohh November 26, 2015 @ 12:37
9396 bytes -1 byte zopfli --i1000 --mls1024 --bsr19 --lazy --ohh November 25, 2015 @ 11:44
9397 bytes -1 byte zopfli --i1000 --mls16384 --bsr8 --lazy --ohh November 25, 2015 @ 11:32
9398 bytes zopfli --i100 --mls16384 --bsr12 --lazy --ohh November 25, 2015 @ 11:27

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

Most recent activity on July 11, 2016 @ 16:21.

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:
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
9406 9406 9406 9406 9406 9405 9406 9407 9411 9413 9413 9400 9403 9406 9406
9397 9397 9396 9396 9396 9395 9397 9396 9397 9396 9400 9406 9399 9399 9403
9398 9398 9398 9400 9398 9397 9396 9396 9396 9397 9398 9399 9398 9396 9396
9397 9397 9403 9397 9403 9399 9395 9396 9395 9396 9399 9399 9401 9399 9406
9397 9397 9396 9397 9397 9397 9395 9396 9399 9401 9397 9399 9399 9396 9396
9398 9398 9397 9397 9397 9400 9400 9396 9395 9396 9396 9399 9399 9398 9399
9397 9397 9397 9397 9400 9399 9397 9396 9395 9396 9396 9400 9399 9399 9399
9397 9397 9396 9397 9396 9396 9396 9396 9396 9396 9396 9399 9399 9397 9405
9401 9401 9397 9397 9396 9396 9395 9396 9396 9396 9396 9400 9399 9396 9399
9397 9397 9396 9400 9397 9399 9395 9397 9399 9396 9396 9399 9399 9396 9396
9397 9397 9397 9396 9400 9397 9397 9396 9397 9396 9396 9399 9399 9395 9399
9397 9397 9396 9397 9396 9399 9396 9396 9396 9397 9399 9398 9399 9398 9399
9396 9396 9396 9396 9396 9397 9396 9396 9396 9401 9397 9398 9399 9395 9399
9396 9396 9397 9396 9396 9397 9397 9396 9396 9396 9396 9399 9399 9395 9399
9397 9397 9397 9396 9397 9399 9395 9396 9396 9396 9396 9399 9399 9395 9399
9396 9396 9397 9396 9397 9397 9395 9396 9396 9396 9397 9398 9399 9396 9399
9396 9396 9397 9396 9397 9396 9396 9396 9396 9396 9396 9398 9399 9396 9399
9396 9396 9397 9397 9396 9399 9395 9396 9395 9396 9396 9398 9399 9396 9399
9397 9397 9397 9396 9396 9397 9396 9396 9396 9396 9396 9399 9399 9396 9396
9397 9397 9396 9396 9397 9396 9395 9396 9398 9396 9396 9399 9399 9396 9399
9397 9397 9396 9397 9397 9397 9395 9396 9396 9396 9396 9399 9399 9396 9399
9397 9397 9397 9396 9396 9397 9396 9396 9396 9396 9396 9399 9399 9396 9399
9397 9397 9397 9396 9397 9396 9395 9396 9398 9396 9398 9398 9399 9396 9399

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 9398 bytes 100%
1,000 9396 bytes -2 bytes 100%
10,000 9396 bytes 100%
100,000 9395 bytes -1 byte 100%
1,000,000 9395 bytes 9.28%
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
9455 bytes +60 bytes (+0.64%)
9455 bytes +60 bytes (+0.64%)
9459 bytes +64 bytes (+0.68%) +4 bytes
9479 bytes +84 bytes (+0.89%) +24 bytes
9486 bytes +91 bytes (+0.97%) +31 bytes
9528 bytes +133 bytes (+1.42%) +73 bytes
9576 bytes +181 bytes (+1.93%) +121 bytes
9609 bytes +214 bytes (+2.28%) +154 bytes
9651 bytes +256 bytes (+2.72%) +196 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
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 7827 bytes -1568 bytes (-16.69%)
ZPAQ (Wikipedia) zpaq zpaq -method 69 8493 bytes -902 bytes (-9.60%)
Brotli (Wikipedia) brotli brotli -q 11 8647 bytes -748 bytes (-7.96%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 8877 bytes -518 bytes (-5.51%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 9132 bytes -263 bytes (-2.80%)
LZMA2 (Wikipedia) xz xz -9 9344 bytes -51 bytes (-0.54%)
ZSTD (Wikipedia) zstd zstd -19 9404 bytes +9 bytes (+0.10%)

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