Base64 Encode
Encode any text or file to Base64 — instantly, privately, in your browser.
Private by design
Text and files are encoded locally. Nothing is uploaded — safe for sensitive content.
Instant encode
Real-time Base64 output as you type, with charset selection for UTF-8, ASCII, and more.
Text or file input
Encode a string for JSON or a config file, or convert any binary file into a portable Base64 string.
What is Base64 encoding?
Base64 encoding converts arbitrary binary data into a string of 64 safe ASCII characters so it can travel through text-only channels — email (MIME), JSON, HTTP headers, HTML/CSS data: URLs, and YAML. Every 3 bytes of input become 4 ASCII characters, so the output is roughly 33% larger than the original.
To go back the other way, use the Base64 Decode tool.
Frequently asked questions
›How do I Base64 encode a string online?
Type or paste your text into the input above. The Base64 output appears instantly. You can choose the source character set (UTF-8 by default) and copy the result with one click.
›How do I Base64 encode a file?
Switch to the File tab and drop or pick any file — image, PDF, archive, certificate. The file is read locally and converted to a Base64 string you can copy into JSON, HTML data: URLs, or API payloads.
›Is this Base64 encoder safe?
Yes. Encoding runs entirely in your browser using the standard btoa and TextEncoder APIs. Your text and files never leave your device — nothing is uploaded, logged, or stored.
›What character set should I encode my text with?
UTF-8 is the right answer for almost every modern web, API, and JSON use case — it handles every Unicode character including emoji. Use ISO-8859-1 or Windows-1252 only when you're integrating with a legacy system that requires it.
›Why is the Base64 output longer than my input?
Base64 represents every 3 bytes of input with 4 ASCII characters, so the output is roughly 33% larger than the original. Padding with '=' characters at the end keeps the length a multiple of 4.
›What's the difference between Base64 and URL-safe Base64?
Standard Base64 uses + and / which have reserved meaning in URLs. URL-safe Base64 (RFC 4648 §5) replaces them with - and _ so the encoded string can be dropped into a URL or filename without further escaping. This tool outputs standard Base64.
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