Base64 Decode

Base64 decoding reverses the encoding process — it converts a Base64 ASCII string back to its original binary or text representation. 'SGVsbG8=' decodes to 'Hello'.

To decode Base64: paste the Base64 string (e.g. 'SGVsbG8=') into a decoder. The output is the original text ('Hello'). Every 4 Base64 characters decode to 3 bytes of original data.

Key Features

• Decodes any valid Base64 or Base64url string back to text.
• Handles padding with = or == correctly.
• Shows character count of the decoded output.
• One-click copy of decoded output.
• Browser-based — no Base64 data is sent anywhere.

How to Use the Tool

1. Paste the Base64 string into the input field.
2. The decoded text appears instantly below.
3. Click 'Copy' to copy the decoded result.

Core Benefits

• Inspect JWT token payloads — JWTs are Base64url-encoded.
• Decode API responses that return Base64-encoded fields.
• Read the embedded content of a data URI image.

Common Use Cases

• Decoding the payload of a JWT token to inspect claims (note: the signature remains secured by the signing key).
• Reading a Base64-encoded HTTP Basic Auth header to see the username:password.
• Decoding Base64-encoded strings in API documentation.
• Inspecting Base64 image data URIs embedded in HTML or CSS.

Pro Tips

• JWT tokens have three parts separated by dots: header.payload.signature — all are Base64url encoded. Decode the payload to see claims like expiry time, user ID, etc.
• If your decoded output looks garbled, the input might be binary data (like an image) — not all Base64 data decodes to readable text.
• Base64url strings use - and _ instead of + and / — this decoder handles both formats.