Supported PDF Formats: What Works Best in FillablePDF

5 min readtechnical

Check which supported PDF formats work best in FillablePDF, what upload limits apply, and which field types you can review or add manually.

Supported PDF Formats & Compatibility

If you are checking supported PDF formats before uploading, the main rule is simple: FillablePDF accepts PDF files. The workflow is built for standard .pdf documents, especially clean digital PDFs exported from Word, Google Docs, Pages, or similar document tools.

This page explains which PDFs usually work best, which ones need more manual review, and which format or export assumptions you should not make about the current product.

What file types can you upload?

The current upload flow accepts PDF files only.

If your source document started as:

  • Microsoft Word
  • Google Docs
  • Apple Pages
  • another document editor

export it to PDF first, then upload that PDF.

That matches the product's core job: turn a static or partially interactive PDF into a fillable document you can review, fill, sign, and download in the browser.

If you are starting from Word, use Convert Word to Fillable PDF. If you are starting from Google Docs, use Create Fillable PDF in Google Docs.

Which supported PDF formats work best?

The supported PDF formats that usually perform best are standard digital PDFs with clear layout structure. In practice, that means:

  • PDFs exported directly from Word, Google Docs, Pages, or another document editor
  • Static PDFs with visible labels, blank lines, and consistent spacing
  • Business forms, applications, contracts, intake forms, and other machine-generated documents
  • PDFs with clean text instead of blurry scan artifacts

These files tend to give the field-detection system clearer signals about where text fields, checkboxes, signature lines, and similar form areas belong.

Can scanned PDFs work?

Yes. Many scanned PDFs can still work, but they usually require more review than digital source files.

Scanned documents are more likely to need manual cleanup when:

  • the scan is blurry or low contrast
  • the page is skewed or shadowed
  • labels are hard to read
  • several fields sit close together
  • the form relies on implied spacing instead of clear lines or boxes

If you have both a scan and the original digital document, upload the digital PDF whenever possible. It is usually faster to review and requires fewer manual corrections.

For more detail on what the system looks for during the first pass, see How PDF Field Detection Works.

What field types are part of the current workflow?

The documented manual add and edit workflow is centered on these field types:

  • text
  • checkbox
  • signature
  • initials

Those are the field types you should assume are part of the current in-browser preparation workflow.

Some PDFs may already contain other interactive field types from the original source document. When that happens, behavior depends on the source PDF structure and the PDF reader used after export. If your document depends heavily on dropdowns, radio buttons, or date-specific widgets, test the finished PDF carefully before you send it out.

If you need a date entry area today, the safest current approach is usually a clearly labeled text field with the expected format shown nearby.

What is not part of the current upload and export flow?

The following should not be treated as product promises in the current workflow:

  • direct DOCX or DOC uploads
  • direct image uploads such as JPG, PNG, TIFF, BMP, or WebP
  • built-in Google Drive, Dropbox, or OneDrive import inside the uploader
  • CSV, Excel, JSON, or HTML export
  • documented manual creation tools for dropdown, radio, or date-picker fields

If you need one of those capabilities, qualify the workflow carefully instead of assuming native support.

File size, retention, and document restrictions

Before uploading, keep these limits in mind:

  • maximum upload size: 10MB
  • upload flow: one PDF at a time
  • password-protected PDFs: unlock them before upload
  • corrupted or invalid PDFs: may fail validation

Uploaded documents are retained temporarily and automatically deleted after 7 days. If you are working with a sensitive file, review the full retention and deletion details in PDF Privacy and File Security.

Common compatibility issues

PDF exported from Word looks wrong

Use Word's Save As PDF or Export to PDF flow rather than printing to PDF. A clean export usually preserves layout more reliably than a print-based workaround.

Field detection misses areas on a scanned form

That usually points to scan quality, unclear labels, or a visually dense layout. Review the draft carefully and add or adjust fields manually where needed.

The PDF behaves differently in different readers

Always open the finished file once in a common PDF reader or browser before sending it out widely. That is especially important when the source PDF already contained its own interactive elements.

FAQ

Do Word files upload directly?

No. Export the Word file to PDF first, then upload the PDF. This keeps the workflow aligned with the product's PDF-first editor.

Can I upload images instead of PDFs?

Not in the current upload flow. If a document starts as an image, turn it into a PDF first and then test the result carefully.

Do you support cloud imports from Google Drive or Dropbox?

Not as a built-in upload integration. Export or download the document as a PDF, then upload it directly.

Can I export CSV or JSON from the form?

The current workflow is centered on PDF output, not structured data export formats such as CSV or JSON.

Do radio buttons or dropdowns work?

If they already exist in the source PDF, behavior can vary by document and reader. The documented manual add and edit surface today is text, checkbox, signature, and initials.

What kind of PDFs are safest to use?

Clean digital PDFs with clear labels and consistent spacing are the safest starting point. When you have a choice, use an exported PDF instead of a scan.