Developer
Base64 Decoder Online
- Browser-based
- No signup
This Base64 decoder online converts encoded strings back to UTF-8 text for debugging API payloads, JWT fragments, and config values. Paste Base64, decode locally, and copy the original text—no upload, no account.
Base64 decoding is the inverse of encoding—it reveals the original bytes as text when those bytes represent UTF-8.
Invalid padding or non-Base64 characters produce errors rather than silent garbage output.
100% Client-Side
Your data never leaves your computer.
How to use this tool
Paste Base64 text into the decoder, click decode, and copy the plain-text output. Switch to encode mode to reverse the operation.
Worked example
Example: decode `SGVsbG8gV29ybGQ=` to `Hello World` when inspecting a mis-encoded webhook field in a support ticket.
When to use this
- Reading encoded fields in API responses.
- Decoding Basic auth header examples in documentation.
- Verifying what was actually encoded before a deployment.
Common examples
- UTF-8 email header value → Base64 for debugging MIME parts.
- Small JSON claim → Base64 segment inspection before JWT assembly.
- Data URL prefix stripped → decode image bytes from `data:image/png;base64,...` payloads.
- Small SVG icon → data URL for inline HTML email test.
- UTF-8 string with emoji → Base64 for API fixture matching production encoding.
What people search for
- base64 encode decode
- base64 encoder online
- base64 decoder
- encode string base64
- base64 converter
Common mistakes
- Decoding URL-safe Base64 with the standard alphabet without translation.
- Treating decoded output as encrypted secrets—it is still plain text.
- Expecting binary file output from a text decoder without file support.
Related long-tail tasks
- base64 to text decoder utf8
- decode base64 image data uri
- base64 decode jwt payload fragment
How it works
Choose Encode or Decode, then paste or type text. Encoding converts UTF-8 text to standard Base64. Decoding accepts standard or URL-safe Base64 (with optional whitespace) and returns the original text. All processing runs in your browser.
Limitations
Results are based on the inputs you provide and may not cover every edge case. This tool is for general use and is not professional advice.
Privacy and file handling
Your data is processed in your browser and is not uploaded to our server.
Related Base64 Encoder & Decoder guides
These pages use the same base64 encoder & decoder with guides tailored to specific search intents.
Frequently asked questions
Does decoding send data to a server?
Standard Utilnivo decode runs locally in your browser.
What if decode fails?
Check for extra whitespace, wrong alphabet, or truncated padding characters.
Can I decode files?
Use file upload on the base tool when available; text paste works for string payloads.
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