Base64 Decoder
Decode Base64 strings back to readable UTF-8 with this free Base64 decoder. Invalid alphabets are rejected with a clear message, and whitespace-wrapped MIME-style input is supported. Ideal when inspecting tokens or config fragments offline.
Like the encoder, decoding never leaves your browser. After decoding JSON-looking payloads, send the result through JSON Formatter for pretty-printing and validation.
Input
Paste or type your content here…
Output
Your result will appear here
Frequently Asked Questions
What if my Base64 has whitespace?
Whitespace is stripped before decoding so pasted MIME lines still work.
Why do I get a validation error?
Characters outside the Base64 alphabet (A–Z, a–z, 0–9, +, /, =) cause a friendly rejection instead of corrupted output.
Can binary downloads be produced?
This Phase-1 page focuses on UTF-8 text output. For images, use a dedicated data-URI tool in a later phase.
Is decoding done on a server?
No - TextDecoder runs locally in your browser.