PDF to Base64 Converter

Base64 exists because some transports only carry text. A PDF is binary, so to put one inside a JSON request body, an XML envelope, a SOAP call to a document service, or an email attachment header, it has to be re-expressed using 64 printable characters. This converter does that step and nothing else — the file is read with the browser's own FileReader and never leaves the machine, which matters given how often the PDF in question is a contract or an invoice.

The practical thing to watch is the size. Encoding turns every three bytes into four characters, so the string is about 33% larger than the file, and then whatever you paste it into adds its own weight — JSON escaping, XML entities, and quoted-printable email encoding all inflate it further. A 4 MB PDF becomes roughly 5.5 MB of string before any of that. Many API gateways cap request bodies at 1 MB or 10 MB, so the encoded size shown below is the number that decides whether the request will be accepted, not the file size on disk.

The output is offered raw and as a data URI. Raw is what an API field wants. The data URI, with the media type prefix, is what you need for an anchor's href or an object's data attribute — though browsers have steadily restricted top-level navigation to data URIs, so a link that opens a PDF this way will be blocked in most of them. Embedding it inside an iframe or an object element still works, and the snippets below use that form.