Base64URL Encode / Decode

URL-safe Base64 (- _ , no padding).

Base64URL Encode / Decode converts text to and from URL-safe Base64, the variant that uses - and _ instead of + and / and omits the trailing = padding. This makes the output safe to drop into URLs, query strings, JWT segments, and filenames without extra escaping. Switch between encode and decode modes to round-trip UTF-8 text in either direction.

Common uses

• Encode a value so it can be placed directly in a URL or query parameter without percent-encoding + / or =
• Decode a Base64URL segment from a JWT (such as the header or payload) back into readable text
• Generate URL-safe tokens or identifiers from plain text
• Inspect or convert Base64URL strings found in API responses, OAuth flows, or cookies
• Produce filename-safe encoded strings that avoid characters disallowed on many filesystems

FAQ

Is my data sent to a server?

No. Encoding and decoding run entirely in your browser using the built-in btoa, atob, TextEncoder, and TextDecoder APIs. Nothing you type is uploaded or stored remotely.

How is Base64URL different from standard Base64?

Base64URL replaces the + character with - and the / character with _, and it strips the trailing = padding. This keeps the output safe for use in URLs and filenames, whereas standard Base64 would need additional escaping.

Does it handle Unicode and emoji?

Yes. Text is encoded as UTF-8 before conversion via TextEncoder and decoded back with TextDecoder, so multi-byte characters and emoji round-trip correctly.

Do I need to add the = padding when decoding?

No. The decoder automatically restores any missing = padding before decoding, so you can paste an unpadded Base64URL string directly.

What happens if I paste invalid input in decode mode?

If the input is not valid Base64URL, decoding fails and the tool reports an 'Invalid Base64URL input' error rather than returning garbled output.

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