List a PDF's AcroForm form fields — names, types, options, current values, per-field maxLength where declared — plus a paste-ready fillTemplate object for pdf_fill and a hasXFA flag (hybrid AcroForm/XFA inputs lose their XFA layer when filled). A PDF with no form returns count 0. Call this FIRST when filling an unfamiliar PDF: you cannot fill fields whose names you do not know, and values longer than a field's maxLength are rejected.

Fill AcroForm form fields in a PDF and save the result. Field names must exist in the PDF (use pdf_inspect first). All values are strings; checkboxes take "true"/"false"; dropdown/radio/optionlist values must be one of the field's options; text values must respect the field's maxLength from pdf_inspect. Encrypted PDFs are rejected with decrypt advice (common for government blanks with an empty user password).

Merge two or more PDFs into one, in the order given, and save the result.

Generate a complete, professionally laid-out invoice PDF from structured data — no template needed. Deterministic: the same input produces byte-identical output (safe to re-run). Note: without a paid PDFops key the output carries a small "Generated with pdfops.dev" footer line.

Check the current PDFops API quota for the configured key: tier, limit, used, remaining, reset date. Requires PDFOPS_API_KEY.