Choose a version:
42% The original file has 145543 bytes (142.1k) and is available from the project website.
There you can find the official minified version, too, which brings down the size to 60404 bytes (59.0k, 42%).

After GZIP compression these minified files vary in size:
Microsoft
  22241 bytes (21.7k)
 CDN
gzip -6 (default)
  16154 bytes (15.8k)
 local copy
jsdelivr
  16133 bytes (15.8k)
 CDN
cdnjs
  16097 bytes (15.7k)
 CDN
gzip -9
  16096 bytes (15.7k)
 local copy
libdeflate -12
  15599 bytes (15.2k)
 local copy
7zip -mx=9 -tgzip
  15583 bytes (15.2k)
 local copy
zultra
  15550 bytes (15.2k)
 local copy
pigz -11 -n
  15526 bytes (15.2k)
 local copy
kzip -s0 -rn -b2
  15524 bytes (15.2k)
 local copy
Zopfli
  15514 bytes (15.2k)
 local copy

perma-link to the smallest file on my server:
http://minime.stephan-brumme.com/files/bootstrap/bootstrap-5.2.3.min.js (or via HTTPS)

You will automatically get the smallest Bootstrap 5.2.3 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 583 bytes by using my Bootstrap 5.2.3 Zopfli version instead of the best available CDN (3.76% smaller than cdnjs, 15514 vs. 16097 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 --mls2048 --bsr16 --lazy --ohh

(found January 5, 2023)
Description Value Parameter
iterations 1000000  --i1000000
maximum blocks 8  --mb8
maximum length score 2048  --mls2048
block splitting recursion 16  --bsr16
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/v5.2.3/dist/js/bootstrap.min.js --location | md5sum
b0794583ec020a7852f0fc04d5cefc52  -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-5.2.3.min.zopfli.js.gz | md5sum
b0794583ec020a7852f0fc04d5cefc52  -

SHA1:
curl --silent --compressed https://raw.githubusercontent.com/twbs/bootstrap/v5.2.3/dist/js/bootstrap.min.js --location | sha1sum
847dff899b5bcf8ee434e389e2a910ba1dbad76f  -
curl --silent --compressed https://minime.stephan-brumme.com/files/bootstrap/bootstrap-5.2.3.min.zopfli.js.gz | sha1sum
847dff899b5bcf8ee434e389e2a910ba1dbad76f  -

All listed CDNs deliver identical contents:
CDN Size (compressed) MD5 (uncompressed) Timestamp
Microsoft 22241 bytes b0794583ec020a7852f0fc04d5cefc52 (invalid)
jsdelivr 16133 bytes b0794583ec020a7852f0fc04d5cefc52 January 3, 2023 @ 16:22
cdnjs 16097 bytes b0794583ec020a7852f0fc04d5cefc52 (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
15514 bytes -1 byte zopfli --i1000000 --mls2048 --bsr16 --lazy --ohh January 5, 2023 @ 17:58
15515 bytes -1 byte zopfli --i10000 --mls2048 --bsr16 --lazy --ohh January 4, 2023 @ 12:47
15516 bytes -1 byte zopfli --i10000 --mls512 --bsr22 --lazy --ohh January 4, 2023 @ 10:51
15517 bytes -1 byte zopfli --i1000 --mls512 --bsr22 --lazy --ohh January 4, 2023 @ 03:13
15518 bytes -1 byte zopfli --i1000 --mls1024 --bsr14 --lazy --ohh January 3, 2023 @ 22:46
15519 bytes -3 bytes zopfli --i1000 --mls256 --bsr40 --lazy --ohh January 3, 2023 @ 18:17
15522 bytes – zopfli --i100 --mls2048 --bsr17 --lazy --ohh January 3, 2023 @ 16:51

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 @ 01:57.

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 15524 15524 15524 15524 15523 15523 15523 15524 15526 15525 15525 15526 15527 15528 15524
4 15524 15524 15524 15529 15517 15518 15518 15520 15520 15519 15520 15518 15525 15525 15519
6 15527 15525 15526 15524 15516 15521 15518 15521 15516 15522 15522 15525 15523 15521 15519
7 15516 15518 15517 15524 15525 15522 15517 15518 15518 15516 15517 15517 15524 15521 15519
8 15520 15526 15520 15526 15521 15521 15521 15525 15525 15524 15525 15523 15523 15527 15528
9 15533 15518 15517 15525 15517 15529 15523 15524 15525 15523 15520 15517 15517 15521 15518
10 15516 15517 15519 15525 15525 15521 15524 15524 15525 15524 15517 15518 15524 15524 15525
11 15525 15517 15516 15525 15526 15525 15525 15517 15528 15519 15521 15517 15525 15521 15525
12 15529 15520 15516 15522 15524 15523 15521 15524 15524 15523 15526 15525 15525 15521 15524
13 15526 15526 15519 15525 15525 15520 15520 15517 15516 15517 15526 15525 15523 15521 15519
14 15521 15518 15520 15517 15520 15521 15518 15516 15518 15516 15514 15517 15520 15534 15519
15 15525 15525 15518 15523 15523 15516 15525 15524 15529 15525 15522 15523 15524 15521 15525
16 15516 15519 15516 15525 15521 15521 15516 15518 15518 15517 15514 15518 15524 15521 15519
17 15525 15520 15524 15524 15523 15521 15520 15525 15516 15525 15514 15517 15517 15521 15519
18 15516 15517 15526 15526 15520 15520 15516 15524 15516 15525 15526 15525 15523 15522 15519
19 15531 15517 15516 15526 15526 15530 15522 15524 15525 15516 15516 15518 15517 15522 15517
20 15516 15520 15520 15526 15522 15526 15523 15517 15516 15523 15525 15525 15523 15522 15519
21 15516 15517 15516 15525 15525 15520 15517 15518 15525 15516 15517 15524 15525 15522 15519
22 15529 15518 15523 15529 15524 15531 15525 15524 15516 15520 15525 15517 15519 15521 15525
23 15516 15517 15516 15525 15525 15526 15516 15517 15534 15524 15525 15517 15523 15521 15519
25 15516 15519 15526 15525 15525 15520 15516 15517 15531 15523 15525 15523 15523 15521 15521
30 15516 15518 15517 15525 15520 15526 15525 15522 15533 15526 15522 15517 15524 15521 15519
40 15516 15525 15517 15525 15519 15525 15517 15516 15516 15525 15519 15523 15522 15522 15518

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 15522 bytes – 100%
1,000 15517 bytes -5 bytes 100%
10,000 15515 bytes -2 bytes 100%
100,000 15515 bytes – 1.16%
1,000,000 15514 bytes -1 byte 0.87%
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) 15612 bytes +98 bytes (+0.63%) +88 bytes
1 15613 bytes +99 bytes (+0.64%) +89 bytes
2 15524 bytes +10 bytes (+0.06%) –
3 15548 bytes +34 bytes (+0.22%) +24 bytes
4 15570 bytes +56 bytes (+0.36%) +46 bytes
5 15594 bytes +80 bytes (+0.52%) +70 bytes
6 15631 bytes +117 bytes (+0.75%) +107 bytes
7 15632 bytes +118 bytes (+0.76%) +108 bytes
8 15675 bytes +161 bytes (+1.04%) +151 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 13103 bytes -2411 bytes (-15.54%)
ZPAQ (Wikipedia) zpaq zpaq -method 69 13458 bytes -2056 bytes (-13.25%)
Brotli (Wikipedia) brotli brotli -q 11 14440 bytes -1074 bytes (-6.92%)
Burrows-Wheeler transform (Wikipedia) bzip2 bzip2 -9 15192 bytes -322 bytes (-2.08%)
LZMA2 (Wikipedia) xz xz -9 15268 bytes -246 bytes (-1.59%)
Zstandard (Wikipedia) zstd zstd -19 15364 bytes -150 bytes (-0.97%)
PPMd (Wikipedia) 7zip 7za a -mx=9 -m0=ppmd 15555 bytes +41 bytes (+0.26%)

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.