Toolbox101 All tools

Encoding

Encode text as Base64URL

Base64URL packs bytes the same way Base64 does, with an alphabet that is safe in URLs: + becomes -, / becomes _, and the trailing = padding is dropped. The result sits in query strings, path segments, OAuth state parameters and JWT segments without percent-escaping. The text is converted to UTF-8 first, so any script or emoji encodes correctly.

Open Base64URL Encode in the app Browse all tools

How to use Base64URL Encode

  1. Open Base64URL Encode in the Toolbox101 app.
  2. Paste the string you want to make URL-safe into the Input box.
  3. Read the result in the Output box; it uses - and _ and has no trailing =.
  4. Click Copy and drop the value into a query string, URL or JWT segment.

Worked example

Base64URL Encode returns the output below for this input.

Input

hello??

Output

aGVsbG8_Pw

Check it yourself: open Base64URL Encode and enter the same input.

Frequently asked questions

What is the difference between Base64 and Base64URL?

Only the alphabet and padding: Base64URL writes + as -, / as _, and omits trailing = padding. Packing is identical, both decode to the same bytes, and the length grows by about a third in either case. The URL-safe alphabet exists because +, /, and = are reserved or awkward inside URLs, and some systems mangle them.

Where is Base64URL encoding actually used?

Mostly in JSON Web Tokens: the header, payload, and signature are three Base64URL strings joined by dots. You also meet it in OAuth state parameters, signed URLs, and anywhere a compact value must survive URLs, headers, and copy-paste unmodified. Padding is dropped because = creates parsing friction in query strings and some systems trim it.

Can the regular Base64 Decode tool read Base64URL?

Here, yes: the Base64 Decode tool in this app accepts both alphabets and missing padding, so Base64URL pastes straight in. Many other decoders do not. The browser's atob, for one, rejects - and _ and needs the alphabet swapped back first.

What characters can appear in Base64URL output?

Only A–Z, a–z, 0–9, -, and _: 64 symbols in total. There is no +, /, or = padding, and every character is unreserved in URLs per RFC 3986, so the encoded value needs no percent-escaping and survives chat apps and HTML forms that would otherwise mangle it.

Use Base64URL Encode now

Open Base64URL Encode in the app

Runs in your browser. Nothing you type is uploaded.