Base64 Encoder/Decoder

How to Use the Base64 Encoder/Decoder:

1. Select Mode: Choose Encode to convert plain text to Base64, or Decode to convert a Base64 string back to plain text. The mode label on the input area updates to reflect your selection.

2. Choose Standard or Base64URL: Toggle the Base64URL switch to convert between standard Base64 (uses + and / characters) and URL-safe Base64URL (replaces + with - and / with _, removes = padding). Use Base64URL for JWT tokens, URL parameters, and filenames.

3. Enter Input: Type or paste your text (for encoding) or your Base64 string (for decoding) into the input area. The tool handles emoji, international characters, and all Unicode text correctly using UTF-8.

4. Click Convert: Click the Convert button to perform the encoding or decoding. The result appears in the output area immediately.

5. Copy Output: Click Copy Output to copy the result to your clipboard. A confirmation toast appears when the copy succeeds.

6. Swap: Use the Swap button to move the current output into the input field and switch modes — useful for round-trip testing (encode then decode to verify).

7. Try a Sample: Click Sample to load an example input with UTF-8 characters including emoji. The conversion runs automatically so you can see what the output looks like.

8. Clear: Click Clear to reset all fields and start fresh.

Common Use Cases:

• API authentication: Encode Basic Auth credentials (username:password) for HTTP Authorization headers
• Data URIs: Embed small images or files directly in HTML/CSS using Base64-encoded data
• JWT inspection: Decode the header and payload segments of a JWT (each is Base64URL-encoded)
• Email MIME content: Decode Base64-encoded email attachment content
• Debugging: Decode Base64 tokens, cookies, or configuration values to inspect their content
• URL-safe encoding: Use Base64URL mode for values passed in query strings or URL path segments

Tips and Best Practices:

• Base64 is encoding, not encryption — anyone can decode it instantly; never use it for security
• Base64 increases data size by approximately 33% (3 bytes → 4 characters)
• Always remove whitespace and newlines from Base64 strings before decoding
• Standard Base64 uses + and / which must be percent-encoded in URLs; use Base64URL instead
• The = padding at the end of a Base64 string is optional in many contexts but required by strict decoders
• For JWT tokens, the header and payload are Base64URL-encoded; the signature is also Base64URL but cannot be decoded to meaningful text without verifying it