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Base64 to PDF Converter

Turn a Base64-encoded PDF from an API or a database back into a document you can read and save.

Input

Output

How to Use

Paste the Base64 string into the input box. A data:application/pdf;base64, prefix and line breaks are fine.
The string is decoded as you paste, and the PDF appears in a viewer below the output.
Click Download to save it as decoded.pdf, or open it in a new tab for a full-size view.
To go the other way, drop a PDF onto the File tab to get its Base64.

Frequently Asked Questions

How do I know the string is a PDF?

A Base64-encoded PDF almost always starts with JVBERi0, which is %PDF- encoded. The tool checks the decoded bytes for that signature and shows the viewer only when it finds it.

Why does it say the Base64 is invalid?

Usually because something else was copied along with it, such as quotation marks, a JSON key or an escaped slash. Paste only the value; spaces, line breaks and missing padding are handled for you.

Is there a size limit?

Very long strings are kept in memory instead of being printed in the output box, so the page stays responsive. The PDF still previews and downloads normally.

Is the PDF uploaded anywhere?

No. Decoding and the preview both happen in your browser, which matters for invoices, contracts and reports that contain personal data.

Decode Base64 to PDF Online

Updated September 29, 2026 · By Saman

Many APIs cannot send a file on its own, so they wrap it in JSON as one long Base64 string: shipping labels, invoices, bank statements and generated reports arrive this way. So do PDFs stored in database columns and email sources. This page is the Base64 Encoder and Decoder set to decode as you paste, with a PDF viewer for the result.

The decoding runs locally in your browser, and the preview uses the browser's own PDF viewer, so the document is never uploaded.

Recognising a Base64 PDF

Every PDF begins with the bytes %PDF-, which become JVBERi0 in Base64. If a string in an API response starts with those seven characters, it is a PDF. A string starting with data:application/pdf;base64, is the same thing with a label in front, and the tool strips that label for you.

Common problems

Escaped slashes: JSON may show \/ instead of /. Copy the value from a parsed response, or replace \/ with / first.
Quotes copied along: the surrounding " characters are not part of Base64 and make the string invalid.
Base64URL: strings that use - and _ are converted automatically.
No viewer appears: the data is not a PDF. The tool still offers the file as a download, named after the type it detects.

Doing it in code

Platform	Decode to a file
Linux / macOS	`base64 -d in.txt > out.pdf`
PowerShell	`[IO.File]::WriteAllBytes('out.pdf', [Convert]::FromBase64String($s))`
Python	`open('out.pdf', 'wb').write(base64.b64decode(s))`
Node.js	`fs.writeFileSync('out.pdf', Buffer.from(s, 'base64'))`

For other file types, Base64 Decode handles text, images and any binary data. To build a PDF from pictures, use Image to PDF.

Guides

Base64 vs Base64URL: What Changes and When to Use Each Base64URL is standard Base64 with two characters replaced, - for + and _ for /, and usually without the = padding. Invalid Base64 String: Why Decoding Fails and How to Fix It A Base64 decoder rejects a string for one of three reasons: a character outside the alphabet, a length that cannot be right, or padding in the wrong place.