Base64 Encoder
Encode text or files to Base64 instantly. See the size cost in real time.
— or drop a file —
How it works
Base64 is a binary-to-text encoding scheme that represents binary data using 64 printable ASCII characters. It is universally used to embed images in CSS, send binary attachments through JSON APIs, and encode credentials for HTTP Basic Auth headers. Every three bytes of input produce four characters of output, meaning Base64 always inflates data by roughly 33%.
This encoder runs entirely in your browser using the Web Crypto API and native btoa primitives. When you paste text, the tool converts it to UTF-8 bytes first, then encodes those bytes. When you drop a binary file — an image, a PDF, a font — the raw bytes are encoded directly. The live stats panel shows input size, output size, and the efficiency ratio so you can decide whether Base64 embedding is worth the payload cost before you commit to it.
Unlike server-based encoders, your data never leaves your device. There is no upload, no server-side processing, and no analytics on the content you encode. The entire operation happens in a single browser tab with zero network requests beyond the initial page load.
FAQ
How much larger does Base64 make my data?
Base64 increases the size by approximately 33%. Three bytes of input become four Base64 characters. The live stats panel above shows the exact ratio for your specific input.
Can I Base64-encode a file larger than 10 MB?
Yes — the encoding runs in your browser's memory. The practical limit depends on your device's available RAM. Files up to ~100 MB work on most modern devices.
What is the difference between Base64 and Base64URL?
Standard Base64 uses + and / as the 62nd and 63rd characters and pads with =. Base64URL replaces those with - and _ and omits padding, making it safe for URLs and filenames.
Is Base64 encryption?
No. Base64 is an encoding, not encryption. Anyone can decode it instantly. Never use Base64 to "hide" passwords, tokens, or secrets — use proper encryption instead.