PDF to Base64 Converter Online - No Upload, Free

Pick a PDF above and this tool turns it into a Base64 string right away. You get three things back: a data URI you can paste straight into an iframe, an embed code block, and the raw Base64 string on its own. Copy any of them with one click or save them as a text file.

The whole thing runs in your browser. Your PDF is not uploaded, so there is no wait, no file size cap, and no account to make. It is free.

How to Convert a PDF to Base64

1. Click Select Pdf and pick the file from your device.
2. The string shows up below the button in a second or two.
3. Hit Copy To Clipboard, or Download Text to save it as a .txt file.

Big files take a moment longer. A 10 MB PDF takes a few seconds on most laptops, because your own machine is doing the work.

What You Get Back

Different jobs need the string in different shapes, so the tool prints all three.

1. Data URI - starts with data:application/pdf;base64,. Drop it in an iframe src and the PDF renders in the page.
2. Embed code - the same string wrapped in an embed tag, ready to paste.
3. Raw Base64 - just the characters, no prefix. This is what most APIs and JSON fields want.

If an API rejects your string, check this first. Sending the full data URI where a raw string is expected is the most common mistake we see.

Your PDF Never Leaves Your Browser

Most online converters work by sending your file to a server, encoding it there, and sending the text back. This page does the opposite. Your PDF is read locally by JavaScript using the browser FileReader API. The bytes never travel - not to us, not to a CDN, not to any third party.

That matters when the PDF is a contract, an invoice, a medical form, or anything else you would not hand to a stranger. Open the tab, convert, close the tab. Nothing is stored anywhere.

It also makes the tool faster. There is no upload bar, no queue, no rate limit, and no size cap, because there is no shared backend to protect.

Why Base64 Makes a File About 33% Bigger

Base64 packs every 3 bytes of the PDF into 4 text characters. That is a 4:3 ratio, so the string always comes out roughly 33% larger than the file. A 1 MB PDF gives you about 1.37 MB of text.

This is the trade you make. You get a PDF that can travel inside JSON, HTML, or an email body, and you pay for it in size. For files over a few MB, a normal file upload is usually the better call.

Where a PDF to Base64 String Actually Gets Used

A few jobs come up again and again:

1. JSON APIs - JSON holds text, not bytes. Base64 is how a PDF rides along in a POST body.
2. Email attachments - MIME has encoded attachments this way since the 1990s.
3. Inline previews - a data URI in an iframe shows a PDF with no file hosting at all.
4. Database columns - storing a small PDF in a text field instead of on disk.

For anything bigger than about 2 MB, think twice. The size bump plus the decode cost usually beats the convenience.

Turning the String Back Into a PDF

Got a string and need the file back? The Base64 to PDF decoder takes the text and gives you a downloadable PDF. It works in the browser too.

Working with other formats? The file to Base64 tool takes any file type, and PNG to Base64 is set up for images with a ready-made CSS and HTML snippet.