Fill PDF Forms
Tax returns. Legal contracts. Medical intake. Some forms shouldn't leave your device.
Fill them in your browser — nothing uploads.
Signature fields will be skipped (sign in a desktop reader or signing service).
{count} fields filled
Low — clean fill
All fillable fields were written to the PDF. Download the filled file below.
{filled} filled, {skipped} signatures skipped
Medium — signatures skipped
Non-signature fields filled successfully. Signature fields need to be signed separately in a desktop reader or signing service.
Form detected
Info — no values written
Form fields detected. You can fill values above, or download the unchanged PDF as-is.
XFA forms are not supported
This PDF uses Adobe LiveCycle Designer's XFA form spec, which Fill PDF Forms does not handle. Open the file in Adobe Reader for desktop to fill XFA forms.
No fillable form
This PDF has no AcroForm fields. Try a different PDF that contains fillable fields.
About filling PDF forms
What kinds of form fields can be filled
Five AcroForm field types: text fields (with sub-modes for multi-line, password masking, and combed character-cell entry), check boxes, radio groups (with the original PDF's option set), dropdowns (single-select or multi-select, plus editable dropdowns that accept free-text entry beyond the option list), and option lists (always-expanded scrollable selection). The tool detects each field's flags from the PDF schema and renders the matching HTML form element — required fields are marked, read-only fields stay visible but disabled, and default values from the form designer pre-populate the inputs. Push buttons (interactive triggers, not fillable) and signature fields (requiring cryptographic signing) are declined.
Why browser-only matters for forms
Form data carries the most sensitive profile in the pdfmundo catalog: tax returns (income, deductions, dependents), legal contracts (terms, signatures, identifiers), medical intake (HIPAA-relevant identifiers + medication lists), financial applications (account numbers, balances, SSNs), HR onboarding (background checks, banking, ID). Server-based form fillers (iLovePDF, Sejda, Smallpdf, PDF24, Adobe Acrobat, DocuSign) all require uploading the PDF before any field-level operation. pdfmundo's fill runs entirely in your browser — the PDF never leaves your device. For sensitive-data forms, the privacy moat is genuine.
What happens to signature fields
Signature widgets are detected but declined for filling. pdf-lib (the browser PDF library that powers pdfmundo's tools) has no cryptographic signing API in v1. Signature fields appear in the form schema as a 'Signature required (skipped)' indicator; the rest of the form's fillable fields work normally. After downloading the partially-filled PDF, sign in a desktop reader (Preview, Adobe Reader) or a dedicated signing service. For PDFs that are mostly signature fields with little other content, a signing-first tool like DocuSign or HelloSign covers that workflow better than Fill PDF Forms.
XFA forms — why they're not supported
XFA (XML Forms Architecture) is a separate PDF form spec maintained by Adobe, distinct from the AcroForm spec that Fill PDF Forms handles. XFA forms were created with Adobe LiveCycle Designer and require Adobe Reader for desktop to fill. If you opened your PDF in a browser PDF viewer and the form fields don't appear, that's a signal the form may be XFA. Adobe deprecated LiveCycle Designer in 2017 but XFA forms persist in older government and enterprise document workflows. For XFA, Adobe Reader desktop is the recommended fallback; pdfmundo's PDF to Text may extract any plain-text content as a last resort.
Workflow chain: fill then protect
After filling a sensitive form, consider Protect PDF to add a password before sharing the filled document over email or file sharing. The recovery chain runs the other direction too: if your fillable PDF is password-protected, remove the password in your PDF software first, then come back to fill. If the PDF is corrupted and won't open at all, Repair PDF may recover it enough to fill — referral chain is fill → repair → re-fill. Each tool stays browser-only; the sensitive document never leaves your device through any link in this chain.
Frequently asked questions
- What kinds of form fields can it fill?
- 5 AcroForm types: text (single-line, multi-line, password, combed), check box, radio group, dropdown (single, multi, editable), option list. Push buttons and signature fields are declined. XFA forms (Adobe LiveCycle Designer's separate spec) are not supported — use Adobe Reader desktop for those.
- Does it support signature fields?
- Signature widgets are detected but declined for filling. pdf-lib has no signing API in v1. Signature fields render as 'Signature required (skipped)'. Fill the rest, download, then sign in a desktop reader or signing service. For signature-heavy workflows, a signing-first tool covers them better.
- What's an XFA form and why isn't it supported?
- XFA (XML Forms Architecture) is a separate PDF form spec maintained by Adobe. XFA forms require Adobe Reader for desktop to fill. Fill PDF Forms supports the older, more widely supported AcroForm spec. If your form was created in Adobe LiveCycle Designer, it's XFA — Adobe Reader desktop is the recommended fallback.
- Are my filled forms uploaded to your servers?
- No. The entire fill operation runs in your browser via pdf-lib. The PDF stays on your device throughout fill + save. This matters specifically for form-fill: tax returns, legal contracts, medical intake, financial and HR forms carry high-sensitivity data. Server-based competitors (Sejda, Smallpdf, PDF24, iLovePDF, Adobe, DocuSign) all require uploading; pdfmundo doesn't.
- Can I save my work and come back later?
- Not in v1. Form values live in the browser session only; closing the tab loses them. Workaround: fill, download, then re-open the filled PDF later if you need to edit further (the output is preserved-editable — recipients with form-aware readers can re-edit the filled values).
- Will the filled PDF still be editable after download?
- Yes. v1 preserves form field structure; form-aware readers (Adobe Reader, Preview) can re-edit. Flatten-to-static (convert filled fields to non-editable page content) is on the v1.1 roadmap. The current default is intentional — most fill workflows expect downstream editability.
- What's the maximum file size?
- 50 MB per file, the catalog standard. AcroForm operations are memory-bound on field count + appearance stream cost; 50 MB is conservative for browser memory.
- What if my PDF is corrupted?
- The fill errors with a `pdf-corrupted` result and a direct link to Repair PDF. Recovery chain is fill → repair → re-fill. If the repaired file still won't parse, PDF to Text may extract content as a last resort.
More PDF tools, coming soon
30+ tools in total — merge, split, convert, OCR, sign, watermark, and more. All free to try.
Back to homepage →