Developer utilities

Base64URL encoder & decoder

URL-safe encoding for text, files and token segments. Processed locally in your browser.

Browser-based processingNo uploads or saved history

Enable JavaScript to convert locally in your browser. Nothing is sent to a conversion server. You can still read the offline command-line recipes.

Only in your browser

Use caseWhich should I use?

URL-safe alphabet (- _), with padding when needed. Padding is a separate protocol choice; select JWT segment for unpadded input and output.

RFC 4648 §5

0 B · UTF-8

0 B

Advanced settings URL-safe · padded · no wrapping

Changing a rule selects Custom. PEM fixes the alphabet, padding and line width; you can choose its line ending.

Alphabet

Include padding =Line wrap Line ending

Auto-convert

Ready. Your data stays in this browser.

UTF-8 text · files up to 10 MiB

No uploadsNo tracking scriptsNo saved historyNo advertising

Technical overview

URL-safe encoding

Base64URL replaces the standard + and / characters with - and _, making encoded bytes easier to use in URLs and filenames. The URL-safe preset includes padding when needed. Choose JWT segment for the unpadded JWS convention.

JWT segments use Base64URL without padding. Decode one segment at a time. Decoding a token does not verify its signature or prove that it can be trusted.

Guides & reference

All guides

Choose the right Base64 standard.

RFC 4648 Base64 and Base64URL, JWT padding, MIME line breaks, PEM envelopes, and strict decoding explained with practical presets.

Standards in practice · 4 min read 02

Base64 is not encryption.

What Base64 protects, what it does not, and how to handle sensitive data.

The essentials · 3 min read 03

Which Base64 do you need?

Standard vs. URL-safe, padding, and the characters that trip you up.

Common gotchas · 3 min read 04

A cheat sheet for your terminal.

Useful Base64 snippets for JavaScript, Python, and your command line.

Keep it handy · 4 min read

Frequently asked questions

Is my input sent to a server?

No. This application converts in browser memory and does not transmit or save your input. The hosting provider receives ordinary page-request metadata when serving the website. Copying and downloading place data on your device. Read the full privacy explanation.

Does this work with emoji, other languages, and files?

Yes. Text is encoded as UTF-8, including emoji and non-Latin scripts. Files use their original bytes. Raw data is limited to 10 MiB; encoded input can be up to 20 MiB. Binary output can be downloaded without opening or executing it.

Can I use it offline?

After the converter and its scripts load, you can keep converting in the open tab without a connection. Reloading offline is not guaranteed. You can also run the command-line examples or self-host the source.

Is Base64 a way to encrypt data?

No. Base64 is reversible encoding with no secret key. Anyone can decode it. Use appropriate encryption and access controls for confidential data.

Are there keyboard shortcuts?

Use Ctrl + Enter (Command + Enter on macOS) to convert. Press Escape while focused inside the converter to clear input and output. Every control works with the keyboard.