Choose a version:
53% The original file has 65813 bytes (64.3k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 34653 bytes (33.8k, 53%).

After GZIP compression these minified files vary in size:
Microsoft
  11996 bytes (11.7k)
CDN, direct link
Boot
  11077 bytes (10.8k)
CDN, direct link
MaxCDN
  11077 bytes (10.8k)
CDN, direct link
Baidu
  9317 bytes (9.1k)
CDN, direct link
cdnjs
  9311 bytes (9.1k)
CDN, direct link
gzip -6 (default)
  9246 bytes (9.0k)
local copy
cdnhttps
  9223 bytes (9.0k)
CDN, direct link
gzip -9
  9216 bytes (9.0k)
local copy
unpkg
  9213 bytes (9.0k)
CDN, direct link
Yandex
  9196 bytes (9.0k)
CDN, direct link
jsdelivr
  9196 bytes (9.0k)
CDN, direct link
libdeflate -12
  8915 bytes (8.7k)
local copy
7zip -mx=9 -tgzip
  8908 bytes (8.7k)
local copy
kzip -s0 -rn -b2
  8901 bytes (8.7k)
local copy
pigz -11 -n
  8861 bytes (8.7k)
local copy
Zopfli
  8855 bytes (8.6k)
local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.3.0.min.js

You will automatically get the smallest Bootstrap 3.3.0 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 341 bytes by using my Bootstrap 3.3.0 Zopfli version instead of the best available CDN (3.85% smaller than jsdelivr, 8855 vs. 9196 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 --mls4096 --bsr23 --lazy --ohh

(found December 1, 2015)
Description Value Parameter
iterations 100000  --i100000
maximum blocks 8  --mb8
maximum length score 4096  --mls4096
block splitting recursion 23  --bsr23
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/v3.3.0/dist/js/bootstrap.min.js --location | md5sum
281cd50dd9f58c5550620fc148a7bc39  -
curl --silent --compressed http://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.3.0.min.zopfli.js.gz | md5sum
281cd50dd9f58c5550620fc148a7bc39  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/twbs/bootstrap/v3.3.0/dist/js/bootstrap.min.js --location | sha1sum
dfb8410ffc10a57d69b81620087c5a0b6027765a  -
curl --silent --compressed http://minime.stephan-brumme.com/files/bootstrap/bootstrap-3.3.0.min.zopfli.js.gz | sha1sum
dfb8410ffc10a57d69b81620087c5a0b6027765a  -

These CDNs send you the original file:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Microsoft 11996 bytes 281cd50dd9f58c5550620fc148a7bc39 (invalid)
Boot 11077 bytes 281cd50dd9f58c5550620fc148a7bc39 (invalid)
MaxCDN 11077 bytes 281cd50dd9f58c5550620fc148a7bc39 (invalid)
cdnjs 9311 bytes 281cd50dd9f58c5550620fc148a7bc39 (invalid)
cdnhttps 9223 bytes 281cd50dd9f58c5550620fc148a7bc39 December 24, 2015 @ 07:36
unpkg 9213 bytes 281cd50dd9f58c5550620fc148a7bc39 July 11, 2016 @ 16:21
Yandex 9196 bytes 281cd50dd9f58c5550620fc148a7bc39 (invalid)
jsdelivr 9196 bytes 281cd50dd9f58c5550620fc148a7bc39 (invalid)

And some CDNs send you a different file:
CDN Size (compressed) MD5 (uncompressed) Comment / Diff Timestamp
Baidu 9317 bytes 6a08a110509efe4a9b380f5a4f034915 only whitespaces differ (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
8855 bytes -1 byte zopfli --i100000 --mls4096 --bsr23 --lazy --ohh December 1, 2015 @ 13:19
8856 bytes -1 byte zopfli --i10000 --mls1024 --bsr8 --lazy --ohh September 10, 2015 @ 17:52
8857 bytes -1 byte zopfli --i10000 --mls512 --bsr13 --lazy --ohh September 10, 2015 @ 17:50
8858 bytes -1 byte zopfli --i1000 --mls512 --bsr4 --lazy --ohh September 10, 2015 @ 16:37
8859 bytes zopfli --i100 --mls4096 --bsr14 --lazy --ohh September 10, 2015 @ 16:27

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:
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
8857 8857 8858 8857 8867 8856 8858 8865 8863 8867 8861 8867 8858 8863 8863
8859 8859 8857 8858 8858 8858 8860 8858 8858 8857 8863 8861 8860 8861 8860
8858 8858 8858 8858 8858 8859 8858 8858 8858 8856 8858 8857 8860 8859 8863
8859 8859 8857 8859 8858 8866 8858 8858 8858 8858 8857 8857 8863 8861 8865
8858 8858 8857 8858 8858 8858 8860 8857 8857 8856 8858 8857 8860 8863 8862
8857 8857 8858 8858 8857 8860 8860 8859 8857 8857 8858 8860 8861 8863 8865
8857 8857 8857 8858 8858 8857 8860 8856 8857 8856 8858 8859 8860 8860 8860
8859 8859 8857 8857 8858 8858 8858 8858 8858 8856 8858 8857 8859 8858 8864
8859 8859 8857 8858 8858 8857 8857 8858 8859 8856 8858 8857 8860 8858 8861
8857 8857 8857 8858 8857 8858 8857 8858 8857 8857 8859 8857 8859 8863 8860
8857 8857 8857 8858 8857 8856 8858 8856 8858 8857 8857 8856 8861 8861 8863
8859 8859 8857 8858 8857 8858 8860 8856 8857 8856 8863 8861 8863 8863 8864
8856 8856 8858 8858 8858 8856 8860 8856 8857 8856 8857 8856 8860 8857 8861
8857 8857 8858 8858 8857 8858 8858 8858 8857 8857 8857 8857 8860 8861 8863
8858 8858 8858 8858 8858 8857 8860 8858 8858 8857 8857 8857 8859 8863 8863
8856 8856 8858 8857 8858 8858 8857 8858 8857 8856 8858 8857 8861 8863 8865
8859 8859 8857 8858 8857 8858 8858 8858 8858 8857 8857 8857 8860 8874 8864
8859 8859 8857 8857 8858 8858 8857 8858 8857 8856 8858 8858 8861 8863 8863
8859 8859 8857 8858 8858 8858 8861 8858 8857 8857 8858 8860 8863 8865 8865
8857 8857 8857 8859 8858 8858 8860 8857 8857 8857 8858 8855 8859 8858 8863
8859 8859 8857 8858 8858 8858 8857 8858 8857 8857 8858 8863 8860 8863 8863
8857 8857 8857 8857 8858 8857 8860 8858 8859 8857 8857 8857 8860 8858 8864
8858 8858 8857 8858 8858 8857 8860 8856 8857 8857 8858 8857 8860 8863 8863

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 8859 bytes 100%
1,000 8857 bytes -2 bytes 100%
10,000 8856 bytes -1 byte 100%
100,000 8855 bytes -1 byte 6.96%
1,000,000 8855 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
8910 bytes +55 bytes (+0.62%) +9 bytes
8911 bytes +56 bytes (+0.63%) +10 bytes
8901 bytes +46 bytes (+0.52%)
8914 bytes +59 bytes (+0.67%) +13 bytes
8948 bytes +93 bytes (+1.05%) +47 bytes
8988 bytes +133 bytes (+1.50%) +87 bytes
9032 bytes +177 bytes (+2.00%) +131 bytes
9066 bytes +211 bytes (+2.38%) +165 bytes
9109 bytes +254 bytes (+2.87%) +208 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 7386 bytes -1469 bytes (-16.59%)
ZPAQ (Wikipedia) zpaq zpaq -method 69 8087 bytes -768 bytes (-8.67%)
Brotli (Wikipedia) brotli brotli -q 11 8153 bytes -702 bytes (-7.93%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 8412 bytes -443 bytes (-5.00%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 8593 bytes -262 bytes (-2.96%)
LZMA2 (Wikipedia) xz xz -9 8824 bytes -31 bytes (-0.35%)
ZSTD (Wikipedia) zstd zstd -19 8870 bytes +15 bytes (+0.17%)

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