AnyTool
Your files never leave your device. All processing happens locally in your browser.

How do I convert a Base64 string to a PDF (and preview it)?

Paste a Base64 string or data: URI onto AnyTool to decode it into a real PDF instantly, with a live in-page preview rendered by pdf.js and a one-click download. You can also drop a PDF to encode it back to Base64 — all in your browser with no upload.

  • Paste raw Base64 or a data:application/pdf;base64,… URI — the prefix is auto-stripped
  • Live in-page PDF preview via pdf.js, plus a download with a custom filename
  • Bidirectional: encode a PDF back to raw Base64 or a full data: URI
  • Validates Base64 and checks the %PDF magic header before download
  • 100% in-browser — files never leave your device, no size cap

What is

Base64 to PDF

Base64 to PDF is decoding a Base64-encoded string (or a data:application/pdf;base64,… data URI) back into the binary bytes of a PDF document, producing a viewable, downloadable file without re-creating it from the original source.

Developer Tools

Related terms

Data URIBase64 EncodingPDFpdf.jsBlob URL

Frequently Asked Questions

Yes — it is completely free with no signup, no watermark, and no limits.

The Base64 to PDF tool is 100% free with no account, subscription, watermark, or API upsell funnel. You can decode and download as many PDFs as you want, and encode PDFs back to Base64 too, with nothing held back behind a paywall.

No — decoding and encoding run entirely in your browser, with no upload.

It decodes with atob, Uint8Array, and Blob and renders with pdf.js entirely client-side, so your Base64 string and PDF never leave your device — unlike tools that POST your data or use expiring download links. It works offline after first load, making it safe for sensitive documents.

Yes — the decoded PDF renders right in the page with pdf.js, no download needed.

As soon as you paste valid Base64 or a data: URI, the PDF is rendered in-page with pdf.js so you can read it before downloading — many converters only let you download and open it in your own reader. It also reports the decoded size and page count.

No fixed cap — only your device memory limits how large a PDF you can decode.

Because everything runs locally, there is no artificial 50 MB cap like some server-side converters impose — the only limit is your browser and device memory. It also tolerates line-wrapped Base64 and URL-safe Base64, which break some other tools.

Detailed Explanation

Methodology

How the Base64 to PDF Converter Works

AnyTool decodes a pasted Base64 string or data:application/pdf;base64,… URI by stripping the data: prefix, normalizing whitespace and URL-safe characters, and converting with atob plus Uint8Array into a Blob it can download. It renders the decoded bytes in-page with pdf.js (getDocument({ data })) for a live preview and reports the decoded size and page count. The reverse mode reads a dropped PDF with FileReader.readAsDataURL to emit raw Base64 or a full data: URI, and the tool validates the %PDF magic header so non-PDF input is flagged.

  • Decodes raw Base64 and data: URIs to a downloadable PDF
  • Live in-page preview rendered with pdf.js
  • Bidirectional encode of PDFs back to Base64 or data URI
  • Base64 and %PDF magic-header validation
  • No fixed size cap beyond browser memory
Privacy & Security

Privacy and Offline Use

Decoding, preview, and encoding all run in the browser with atob, Blob, and pdf.js and no runtime CDN, so the Base64 string and PDF never leave the device — unlike converters that upload your data or hand back expiring download links. The tool works offline after first load and has no signup.

Base64 to PDF: AnyTool vs typical converters
CapabilityAnyToolTypical converters
In-page rendered PDF previewYesOften download-only
Encode and decode in one toolYesUsually separate pages
Data URI + URL-safe Base64 handlingYesVaries
Processing locationIn-browserSometimes server-side
File-size capBrowser memory onlyOften 50 MB

Capabilities reflect the live AnyTool tool; competitor behavior varies by service.