Why file to base64 javascript?
Encode a file to base64 in JavaScript is one of the most common tasks developers hit when working with APIs, files, email attachments, and data URIs.
More Base64 guides on base64app — with copy-paste code and a free browser tool you can use without installing anything.
Quick reference
Base64 maps every 3 bytes to 4 ASCII characters. Padding with = may appear at the end. URL-safe variants swap +/ for -_.
When in doubt, paste your string into the tool below — base64app auto-repairs whitespace, data: prefixes, and padding issues.
Copy-paste code
File to base64 (browser)
const input = document.querySelector('input[type=file]');
input.addEventListener('change', async () => {
const file = input.files[0];
const buf = await file.arrayBuffer();
const b64 = btoa(String.fromCharCode(...new Uint8Array(buf)));
console.log(b64);
});