Base64 encode & decode, online

Q: What is a data URI?

A Base64 payload with a MIME prefix, like data:image/png;base64,…, which you can embed directly in HTML or CSS. Build one with the data URI generator.

Paste text or drop a file or image to get Base64 instantly. URL-safe, no padding, MIME line breaks, any charset. Everything runs locally in your browser.

Base64URL encoder MIME encoder Data URI generator Base64 to image Base64 to PDF Base64 to hex Base64 validator

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SGVsbG8sIHdvcmxkIQ==

UTF-8text

Base64 encoder Text to Base64, UTF-8 safe

aGVsbG8gZnJvbSB0aGUgaHVi

UTF-8text

Base64 decoder Base64 back to readable text

data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAA

PNGimage

Image to Base64 PNG, JPG, GIF, WebP, SVG to data URI

eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiIxMjM0In0

JWTtoken

JWT decoder Header, payload, expiry and signature check

/9j/4AAQSkZJRgABAQEASABIAAD/2wBDAAgGBgcG

JPGimage

Base64 to image Preview and download images

aHR0cHM6Ly9leGFtcGxlLmNvbS8_cT0x

URLtext

Base64URL encoder URL-safe Base64, no padding

UEsDBBQAAAAIAGVhW1kAAAAAAAAAAAAAAAAJ

ZIPfile

File to Base64 Any file, several at once, any size

JVBERi0xLjcKJcfsj6IKNSAwIG9iago8PC9M

PDFfile

Base64 to PDF View and save PDFs

48 65 6c 6c 6f → SGVsbG8=

HEXbytes

Hex to Base64 Hex dump in, Base64 out

Authorization: Basic dXNlcjpwYXNz

HTTPheader

Basic Auth header user:password to Authorization header

SUQzBAAAAAAAI1RTU0UAAAAPAAADTGF2ZjU4

MP3audio

Base64 audio player Play and save Base64 audio

SGVsbG8= ✓ valid · 5 bytes · padded

CHECKcheck

Base64 validator Check alphabet, length and padding

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How Base64 works

3 bytes in, 4 characters out. That is the whole trick.

Full explainer

“Man” → TWFu

Text

Man

Bytes

7797110

Bits

010011010110000101101110

6-bit

010011010110000101101110

Index

1922546

Base64

TWFu

Input not a multiple of 3? The tail is padded with =. Every 3 bytes become 4 characters, so output grows by about 33%. More: padding explained, Base64 vs Base64URL.

The alphabet Alphabet table

A0 B1 C2 D3 E4 F5 G6 H7 I8 J9 K10 L11 M12 N13 O14 P15 Q16 R17 S18 T19 U20 V21 W22 X23 Y24 Z25 a26 b27 c28 d29 e30 f31 g32 h33 i34 j35 k36 l37 m38 n39 o40 p41 q42 r43 s44 t45 u46 v47 w48 x49 y50 z51 052 153 254 355 456 557 658 759 860 961 +62 /63

Characters worth knowing

The ones you keep seeing in your output, and why

All 65 characters

=PaddingAlways shows up at the end AIndex 0Six zero bits – every null byte starts here /SlashBanned from URLs, still thriving +PlusBecomes - in URL-safe Base64 eIndex 30Opens most JSON objects: eyJ…gIndex 32Usually right before ==wIndex 48The “w” in a trailing “w==”9Index 61Last of the digits

Base64 in your language

Copy-paste snippets for encode and decode

All languages

JavaScriptnew TextEncoder().encode("hi").toBase64() // aGk=Pythonbase64.b64encode(b"hi").decode() # aGk=PHPbase64_encode('hi'); // aGk=JavaBase64.getEncoder().encodeToString("hi".getBytes()) // aGk=C#Convert.ToBase64String(Encoding.UTF8.GetBytes("hi")) // aGk=Go (Golang)base64.StdEncoding.EncodeToString([]byte("hi")) // aGk=Node.jsBuffer.from("hi").toString("base64") // aGk=Bashprintf '%s' hi | base64 # aGk=

Learn

Guides that answer the next question

All guides

3→4Explainer · 6 min readHow Base64 works ==Explainer · 5 min readPadding (=)-_Guide · 5 min readBase64 vs Base64URL !=Security · 6 min readEncoding vs encryption

FAQ

Short answers, links to the long ones

Is Base64 encryption?

No. It is an encoding, and anyone can reverse it. For secrets, encrypt first, then encode. See encoding vs encryption.

What is the difference between Base64 and Base64URL?

Base64URL swaps + and / for - and _ and usually drops padding, so the result is safe in URLs and filenames. Try the Base64URL tool.

Why is my output about 33% bigger?

Every 3 bytes become 4 characters. Line breaks in MIME mode add a little more. Check exact sizes with the size calculator.

Can I convert images and files?

Yes: image to Base64, file to Base64 and back with Base64 to image or Base64 to file. Nothing is uploaded.

Why does decoded text look garbled?

The bytes are probably binary or in another charset. Switch the charset or decode to a file.

What is a data URI?

A Base64 payload with a MIME prefix, like data:image/png;base64,…, which you can embed directly in HTML or CSS. Build one with the data URI generator.

Do you store or see my data?

No. The pages are static files and the tools run in JavaScript on your device. A Content Security Policy blocks every network request from the page except Cloudflare’s page-view count, so there is nowhere for your data to go. Details.

Is base64hub really free?

Yes. No accounts, no limits, no premium tier hiding the good stuff.

Nothing leaves your browser

Every tool here runs on your device. Load a page once and it keeps working offline.

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