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Base64

Base64 Encoder / Decoder

Encode any text to Base64, or decode Base64 back to plain text -- instantly, entirely in your browser.

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Output
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Disclaimer: This tool runs entirely in your browser -- nothing you enter is sent to or stored on our servers.

What Base64 Encoding Actually Does

Base64 encoding converts binary data into a text-safe ASCII string using 64 printable characters (A-Z, a-z, 0-9, +, /). It is not encryption -- anyone can decode Base64 instantly, so never use it to protect sensitive data. Base64 increases data size by approximately 33% (every 3 bytes become 4 characters), and it's used to embed binary data such as images and files into text-based formats like JSON, XML, HTML, CSS, and email attachments.

Common use cases: embedding images as data URIs in CSS or HTML (data:image/png;base64,...); HTTP Basic Authentication headers where username:password is Base64-encoded; JWT tokens where the header and payload are Base64url-encoded; storing binary data in JSON API responses; and encoding file attachments in SMTP email using MIME encoding. Base64url is a variant using hyphen and underscore instead of plus and slash, making it safe for URLs and filenames without percent-encoding.

Worked Example

Encoding the text "Hello, SmartUtilz!" produces SGVsbG8sIFNtYXJ0VXRpbHoh -- and decoding that string back returns the original text exactly, demonstrating that Base64 is fully reversible (unlike a hash, which is one-way).

Frequently Asked Questions

No -- Base64 is an encoding scheme, not encryption. It has no secret key and anyone can decode it instantly using any Base64 decoder (including this one). If you need to protect sensitive data, use actual encryption (like AES) rather than Base64 encoding alone.
Base64 encodes every 3 bytes of input as 4 output characters, so encoded text is always about 33% larger than the original data. This overhead is the tradeoff for making binary data safely representable in text-only formats like JSON, XML, or email.
Standard Base64 uses '+' and '/' as two of its 64 characters, both of which have special meaning in URLs. Base64url replaces these with '-' and '_' instead, making the output safe to use directly in URLs and filenames without additional percent-encoding -- commonly seen in JWT tokens.
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