2026-09-09
Base64.guru is a solid, purpose-built file-to-Base64 converter that handles a wide range of file types well. If you're searching for an alternative to it specifically, the usual reason is that the file you need encoded isn't a throwaway test asset — it's a real document, and converting it means uploading it to a server first just to get a text string back.
Base64-encoding a file is often step one of embedding it in a JSON payload or an API request body, and the files that end up needing this most — signed contracts, ID scans, invoices — are exactly the ones you'd rather not hand to a third-party site along the way, even briefly.
PDF to Base64 reads a PDF file using the browser's own FileReader API and encodes it to a Base64 string entirely client-side — the file never leaves your device to produce the output. Copy the string directly or download it as a .txt file. Keep in mind Base64 encoding inflates size by roughly a third (every 3 bytes of binary becomes 4 characters of text), so very large PDFs can produce strings too large to be practical for some APIs regardless of which tool encodes them.
This is a dedicated PDF-focused tool, not a general file encoder. Base64.guru supports a much wider range of file types — images, audio, arbitrary binaries — through one interface, which matters if PDFs aren't the only thing you're converting. For a file that isn't sensitive, uploading it to a broader tool isn't really a downside.
For encoding a PDF you'd rather keep local, PDF to Base64 does the conversion without an upload step. If you need to encode file types beyond PDFs, or the file isn't sensitive, Base64.guru's broader format support covers more ground in one place.