Decode URL-safe Base64 encoded strings back to text

Decode URL-safe Base64 into bytes while restoring omitted padding.

freeworks offlinenothing uploaded
ToolBase64URL Decode
Input
Output
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Preview

How it works

URL-safe - and _ map to the standard 6-bit alphabet, missing padding is restored to a multiple of four, and 24-bit groups become bytes. The result can be arbitrary binary.

  • Omitted padding keeps tokens URL-safe.
  • Restoring padding preserves byte boundaries.

Worked example

Decode Base64URL
Decode a URL-safe Base64 string back to text
Input
											SGVsbG8sIFdvcmxkIQ
Output
												Hello, World!

When to use this

JWTs, URL keys, and WebAuthn or OAuth debugging decode Base64url.

Edge cases

  • Standard + and / are invalid in strict URL-safe mode.
  • One or two missing padding characters need restoration.
  • Binary output can contain nulls and invalid UTF-8.

References