usefulweb.site PDF Form & Signature Studio

PDF & documents

PDF Form & Signature Studio

List and fill PDF form fields, and place a visible signature image or typed name on a page.

Max 100 MB. Processed on our server and deleted; the result can be downloaded for about 2 hours.

Field values

Field name exactly as listed. Checkboxes: yes/no. Radio buttons and drop-downs: one of the listed options. Multi-select lists: options separated by ";".

Field values
#Field nameValue
1
2
3
4

Optional: one "field name = value" per line (useful for long forms).

PNG with a transparent background works best. A white JPG background is made transparent. Max 5 MB.

Rendered in a handwriting-style font when no image is uploaded.

pt

72 pt = 1 inch = 25.4 mm. An A4 page is 595 × 842 pt, US Letter 612 × 792 pt.

pt
pt

The height follows from the image proportions.

Used only to open the file for this conversion; it is written to a private temporary file, never to a command line, and deleted with the job.

Try an example: List the fields of a registration form · Fill the form and flatten it · Typed signature at the bottom of a letter

How it works

Shows every field of a fillable PDF (name, type, value, options), fills text fields, checkboxes, radio buttons and drop-downs, and optionally flattens the form. It can also stamp a visible signature, from an uploaded PNG/JPG or a typed name in a script font, at an exact position on any page. This is a picture of a signature, not a cryptographic digital signature.

  • Fields are read with qpdf's JSON view of the AcroForm (/AcroForm /Fields): full name, type (text, checkbox, radio, drop-down, list, signature), current value, options and page. XFA-only forms (dynamic Adobe forms) are not supported.
  • Values are written into the field objects (/V, and /AS for checkbox/radio widgets). /NeedAppearances is set to true so viewers redraw the fields, and qpdf --generate-appearances draws text and choice fields so they show up everywhere, including when flattened.
  • Checkboxes accept yes/no (or the on-state name), radio buttons and drop-downs one of their options. Read-only fields, unknown names and invalid options are skipped and listed, never guessed.
  • Visible signature: the image (or the typed name rendered in a handwriting-style font with ImageMagick) is placed on a transparent overlay page of exactly the target page size at 200 DPI, converted with img2pdf and laid over the page with qpdf --overlay. Positions are in points from the top-left corner.
  • This is NOT a cryptographic (digital) signature: it proves nothing about who signed or whether the document was changed. Use a qualified e-signature service when a legally binding electronic signature is required.

A visible signature image is not a digital signature. Existing digital signatures in the PDF become invalid when you fill or stamp it.

For scripts and AI agents

  • JSON API: POST https://pdfformsignaturestudio.usefulweb.site/api/v1/calculate (same calculation as this page)
  • Interface description: OpenAPI 3.1 · AI guide: llms.txt
  • MCP server (Streamable HTTP): https://pdfformsignaturestudio.usefulweb.site/mcp · tool name pdf_form_signature_studio
Example request
curl -s -X POST https://pdfformsignaturestudio.usefulweb.site/api/v1/calculate \
  -H 'content-type: application/json' \
  -d '{…see OpenAPI examples…}'

Related tools

  • PDF Merge, Split & Reorder – Merge PDFs, split by page count or ranges, and reorder, remove, rotate or duplicate pages.
  • Secure PDF Redactor – Black out names, numbers or areas in a PDF for real: the text is removed, not just covered.
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