Choose a version:
42% The original file has 145677 bytes (142.3k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 60480 bytes (59.1k, 42%).

After GZIP compression these minified files vary in size:
Microsoft
  22280 bytes (21.8k)
 CDN
gzip -6 (default)
  16169 bytes (15.8k)
 local copy
jsdelivr
  16147 bytes (15.8k)
 CDN
cdnjs
  16108 bytes (15.7k)
 CDN
gzip -9
  16107 bytes (15.7k)
 local copy
libdeflate -12
  15612 bytes (15.2k)
 local copy
7zip -mx=9 -tgzip
  15592 bytes (15.2k)
 local copy
zultra
  15560 bytes (15.2k)
 local copy
pigz -11 -n
  15539 bytes (15.2k)
 local copy
kzip -s0 -rn -b2
  15535 bytes (15.2k)
 local copy
Zopfli
  15523 bytes (15.2k)
 local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/bootstrap/bootstrap-5.2.2.min.js (or via HTTPS)

You will automatically get the smallest Bootstrap 5.2.2 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 585 bytes by using my Bootstrap 5.2.2 Zopfli version instead of the best available CDN (3.77% smaller than cdnjs, 15523 vs. 16108 bytes):
Download
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 --mls16384 --bsr19 --lazy --ohh

(found January 5, 2023)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 16384  --mls16384
block splitting recursion 19  --bsr19
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/v5.2.2/dist/js/bootstrap.min.js --location | md5sum
c5236e5d6a5d0ff97ff8c8e5102c6c03  -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-5.2.2.min.zopfli.js.gz | md5sum
c5236e5d6a5d0ff97ff8c8e5102c6c03  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/twbs/bootstrap/v5.2.2/dist/js/bootstrap.min.js --location | sha1sum
6fbfdbddbe85c578de559adcc8d07cccbc16d514  -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-5.2.2.min.zopfli.js.gz | sha1sum
6fbfdbddbe85c578de559adcc8d07cccbc16d514  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Microsoft 22280 bytes c5236e5d6a5d0ff97ff8c8e5102c6c03 (invalid)
jsdelivr 16147 bytes c5236e5d6a5d0ff97ff8c8e5102c6c03 January 3, 2023 @ 16:20
cdnjs 16108 bytes c5236e5d6a5d0ff97ff8c8e5102c6c03 (invalid)

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

Other Versions

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

5.2.3, 5.2.2, 5.2.1, 5.2.0,
5.1.3, 5.1.2, 5.1.1, 5.1.0,
5.0.2, 5.0.1, 5.0.0,
4.6.0,
4.5.3, 4.5.2, 4.5.1, 4.5.0,
4.4.1, 4.4.0,
4.3.1, 4.3.0,
4.2.1, 4.2.0,
4.1.3, 4.1.2, 4.1.1, 4.1.0, 4.0.0,
3.4.1, 3.4.0,
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
15523 bytes -1 byte zopfli --i1000000 --mls16384 --bsr19 --lazy --ohh January 5, 2023 @ 22:35
15524 bytes -1 byte zopfli --i100000 --mls8 --bsr30 --lazy --ohh January 4, 2023 @ 12:21
15525 bytes -3 bytes zopfli --i10000 --mls2048 --bsr12 --lazy --ohh January 4, 2023 @ 10:51
15528 bytes -1 byte zopfli --i1000 --mls2048 --bsr12 --lazy --ohh January 3, 2023 @ 18:52
15529 bytes -1 byte zopfli --i1000 --mls512 --bsr22 --lazy --ohh January 3, 2023 @ 18:20
15530 bytes – zopfli --i100 --mls512 --bsr40 --lazy --ohh January 3, 2023 @ 16:39

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

Most recent activity on January 6, 2023 @ 02:27.

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
2 15534 15534 15533 15534 15533 15532 15532 15533 15536 15535 15535 15535 15537 15539 15534
4 15534 15534 15533 15538 15539 15533 15531 15531 15527 15528 15529 15528 15537 15535 15536
6 15531 15535 15526 15536 15535 15525 15527 15533 15532 15530 15526 15530 15534 15529 15531
7 15527 15527 15526 15536 15529 15525 15534 15533 15534 15529 15532 15527 15532 15532 15528
8 15530 15535 15536 15536 15532 15525 15533 15534 15534 15532 15533 15532 15533 15534 15531
9 15542 15529 15526 15541 15527 15542 15533 15533 15534 15532 15529 15526 15533 15529 15537
10 15538 15535 15536 15536 15528 15525 15534 15530 15534 15526 15526 15527 15530 15532 15535
11 15536 15528 15526 15535 15535 15529 15525 15527 15536 15530 15530 15526 15534 15535 15528
12 15541 15529 15533 15541 15528 15529 15530 15533 15534 15529 15525 15533 15534 15529 15535
13 15529 15535 15536 15535 15535 15535 15525 15533 15534 15530 15535 15530 15533 15529 15528
14 15531 15528 15536 15533 15528 15526 15528 15526 15526 15528 15525 15526 15530 15543 15528
15 15529 15535 15536 15534 15533 15542 15534 15533 15544 15530 15530 15532 15533 15530 15536
16 15526 15528 15526 15530 15529 15528 15525 15527 15527 15526 15525 15527 15534 15529 15527
17 15529 15530 15533 15541 15529 15530 15528 15533 15526 15529 15525 15526 15531 15529 15528
18 15527 15527 15536 15536 15529 15530 15525 15533 15534 15534 15525 15531 15533 15529 15528
19 15529 15527 15526 15528 15534 15542 15532 15533 15534 15529 15525 15527 15527 15523 15527
20 15527 15528 15526 15536 15535 15535 15533 15533 15534 15532 15525 15532 15533 15530 15528
21 15527 15527 15526 15536 15535 15525 15525 15527 15526 15528 15526 15533 15534 15529 15528
22 15527 15528 15537 15533 15534 15539 15534 15533 15527 15529 15526 15526 15537 15529 15531
23 15525 15527 15526 15534 15531 15528 15526 15527 15533 15534 15533 15526 15530 15530 15528
25 15527 15529 15535 15534 15528 15528 15525 15526 15527 15529 15530 15532 15533 15529 15531
30 15529 15528 15524 15535 15526 15535 15526 15533 15532 15534 15526 15532 15534 15529 15528
40 15525 15536 15525 15536 15528 15536 15528 15526 15526 15529 15526 15532 15532 15530 15528

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 15530 bytes – 100%
1,000 15528 bytes -2 bytes 100%
10,000 15525 bytes -3 bytes 100%
100,000 15524 bytes -1 byte 6.67%
1,000,000 15523 bytes -1 byte 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
(any) 15626 bytes +103 bytes (+0.66%) +91 bytes
1 15626 bytes +103 bytes (+0.66%) +91 bytes
2 15535 bytes +12 bytes (+0.08%) –
3 15557 bytes +34 bytes (+0.22%) +22 bytes
4 15582 bytes +59 bytes (+0.38%) +47 bytes
5 15604 bytes +81 bytes (+0.52%) +69 bytes
6 15639 bytes +116 bytes (+0.75%) +104 bytes
7 15640 bytes +117 bytes (+0.75%) +105 bytes
8 15683 bytes +160 bytes (+1.03%) +148 bytes

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 - for example, your browser actually supports it !
Algorithm Program Parameters Size Compared To Best Zopfli
RAR (proprietary) RAR rar a -m5 -md64m -mc63:128t -mt1 13106 bytes -2417 bytes (-15.57%)
ZPAQ (Wikipedia) zpaq zpaq -method 69 13465 bytes -2058 bytes (-13.26%)
Brotli (Wikipedia) brotli brotli -q 11 14448 bytes -1075 bytes (-6.93%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 15206 bytes -317 bytes (-2.04%)
LZMA2 (Wikipedia) xz xz -9 15284 bytes -239 bytes (-1.54%)
Zstandard (Wikipedia) zstd zstd -19 15374 bytes -149 bytes (-0.96%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 15565 bytes +42 bytes (+0.27%)

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):
Load and Parse Data


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 2026.
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

All trademarks are property of their respective owners. You know, the boring legal stuff.