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Base64 Decoder

Decode standard Base64 or Base64URL strings with automatic detection, strict validation, and multi-level conversion.

Base64 Decoder
Base64 Input
Decoded Text

Instant Base64 String Decoding

Decode binary data into human-readable text without the risk of server-side logging. Our tool handles standard and URL-safe Base64 encoding schemes with zero-latency.

Zero Data Transmission

Security Notice

"Base64 is an encoding, not encryption. Anyone can decode it. Our local execution ensures that even if you're decoding sensitive keys, they never leave your machine."

Decode Base64 and verify the expected byte format

Base64 decoding recovers bytes. This text-oriented tool interprets those bytes as UTF-8, which is appropriate for encoded text but not every image, archive, or executable file.

Example input

SGVsbG8sIOS4lueVjA==

Expected output

Hello, 世界

Behavior

  • Decodes standard padded Base64 text.
  • Supports deliberate repeated decoding for nested text encodings.
  • Copies the exact displayed result.

Limits and edge cases

  • Decoded bytes are not guaranteed to be valid UTF-8 text.
  • Base64url uses a slightly different alphabet and optional padding.
  • Treat decoded HTML, commands, and tokens as untrusted content.

Processing note: tool input stays in the browser. Readme.now analytics records page usage, not the payload you paste or the generated output.

Authoritative reference: RFC 4648: Base-N encodings

Related tools

Continue the workflow without copying data to a server.

Encode Base64Encode UTF-8 text as Base64.URL decodeDecode percent-escaped input.Decode JWTInspect JWT header and payload claims.