Base64 Decoder
Decode any Base64-encoded string instantly in your browser. Private, fast, and supports URL-safe Base64 and line-by-line decoding.
How to Use
Why Use This Tool
Base64 encoding is everywhere, in API tokens, email attachments, JWT payloads, and image data URIs. This tool gives you a fast, private way to inspect encoded values without installing anything.
100% Private
All decoding happens in your browser. No data is ever sent to a server.
Instant Results
Decoding runs in microseconds, with no page reloads or waiting.
Line-by-line Mode
Decode batches of Base64 values at once, with per-line error reporting.
URL-safe Support
Automatically handles URL-safe Base64 (- and _) with no extra steps.
What Is Base64 Encoding?
Base64 is a binary-to-text encoding scheme that converts binary data into a string of 64 printable ASCII characters (A–Z, a–z, 0–9, +, /). The name comes from the 64-character alphabet it uses.
It is commonly used to encode binary data such as images, cryptographic keys, or file attachments so it can be safely transmitted over systems that handle only text, like HTTP headers, JSON payloads, or email (MIME).
Decoding reverses the process. It converts the Base64-encoded text back into its original form. This tool does exactly that and outputs the original plain text directly in your browser.
Frequently Asked Questions
+ with - and / with _, and often omits the = padding. This tool automatically converts those characters back to standard Base64 and adds missing padding before decoding.