PDF Form Filler — Fill Interactive PDFs Online
Fill an interactive PDF form in your browser, then download the completed copy. Supports text, checkbox, radio and dropdown fields with an optional flatten step that locks every value into the page.
Drop your PDF hereTap to select a file
Supports PDF, up to 100MB
How it works
- 1Drop a PDF that contains an interactive form (AcroForm fields).
- 2The tool reads the fields and renders one input per field — text, checkbox, radio, or dropdown.
- 3Type or pick values directly in this page. Nothing is uploaded.
- 4Click Generate filled PDF. The values are written into the form and (with Flatten on) baked into the page content.
- 5The completed PDF downloads automatically. Open it anywhere — the values are part of the document.
What to do next
About PDF Form Filler
Filling a PDF form online still inexplicably means uploading the document to one of a dozen interchangeable SaaS tools that retain the file for "convenience" and force a sign-up wall before the download button works. The PDF Form Filler does the same job inside your browser tab using the open-source pdf-lib JavaScript library. Drop in any PDF that contains real AcroForm fields — text inputs, checkboxes, radio groups, dropdown lists — and the tool reads the field tree, lets you type or toggle each value, and exports a filled copy without ever sending the document to a server.
The tool handles the boring details that separate a real form filler from a "draw text on top" hack. Field appearances are regenerated when values change so the filled output renders identically in every PDF viewer, including Apple Preview which is famously strict about appearance streams. Multi-line text fields wrap correctly. Radio button groups elect the chosen option exclusively. Checkboxes use the embedded export value the form designer specified, not a hard-coded "Yes" string that often shows as nothing in third-party viewers. The result is a PDF that opens, displays, and prints the way the form's author intended.
If you need a copy that nobody can re-edit — for example, a signed timesheet you do not want a manager to silently change — toggle the Flatten option before exporting. Flattening converts every form field into baked-in page content, after which the PDF behaves like any other static PDF: viewers cannot select or modify the values you entered. There is a trade-off — flattening invalidates any existing digital signature on the document because it is itself a modification of the bytes — and the tool surfaces that fact in the success metrics so you do not flatten a signed contract by accident.
Two kinds of forms are deliberately not supported. The first is XFA-only forms — an older XML-based interactive-form variant that some legacy desktop PDF editors produce in place of standard AcroForm. pdf-lib does not write XFA, so the tool reports a clear error if you upload one. Re-saving the file as a Standard PDF in any modern PDF editor that supports XFA → AcroForm conversion produces a copy this tool can fill. The second is "static" PDFs masquerading as forms — files where the form-like fields are actually just drawn lines and boxes with no interactive overlay. There is nothing to fill on those; use Add Text to PDF for that case.
How it works
- 1Drop a fillable PDF onto the upload area. Files up to 100 MB are accepted.
- 2The tool reads the AcroForm tree and lists every field by name with its current value.
- 3Type values into text fields, tick checkboxes, pick radio options and select dropdowns. Field appearances regenerate as you type so the preview matches the export.
- 4Optional: tick Flatten if you want the filled values to be locked into the page content so reviewers cannot edit them.
- 5Press Save. pdf-lib writes a fresh PDF with your values applied, and you get an instant download.
Common use cases
- Fill a government tax form on your laptop instead of printing, hand-writing, scanning and re-uploading it
- Complete an HR onboarding packet for a new hire and email the filled copy without a paid PDF editor licence
- Type values into a fillable invoice template and send the flattened result to a client
- Submit a school enrolment form online without installing a desktop PDF editor
- Pre-fill a stack of identical event waivers for an offline batch print run
- Test a fillable form during development to confirm every field accepts the right value before publishing the template
FAQ
Which kinds of PDF forms work?
Standard AcroForm fields — text input, checkboxes, radio buttons and dropdown lists. Most government, banking and HR forms use AcroForm. Older XFA-only forms (an XML-based interactive-form variant some legacy desktop PDF editors produce) are not supported; the tool reports a clear error if you upload one. Re-saving an XFA form as a Standard PDF in any modern editor that supports XFA→AcroForm conversion produces a copy this tool can fill.
Does my PDF leave the browser?
In your browser. The file is read into memory inside the tab, edited with the open-source pdf-lib library, and the filled copy is offered as a direct download.
Can I lock the values so reviewers cannot change them?
Yes — toggle the Flatten option before exporting. Flattening converts the editable form fields into baked-in page content so the PDF can no longer be re-edited in any viewer.
How big can the form be?
Up to 100 MB. The processor holds the input plus the output in memory at once, so the cap is intentionally lower than the standard PDF tool ceiling.
Does it preserve digital signatures?
Existing digital signatures are preserved if you do not flatten. Flattening invalidates any signature that was already on the document, because the act of flattening itself is a modification of the file.
Will it preserve the form’s field validation rules?
AcroForm validation rules — required, format, range, custom JavaScript — are stored in the form definition itself; pdf-lib preserves them in the output. Note that pdf-lib does not run those rules during your fill session, so it is possible to enter a value the form’s author intended to reject. The downstream viewer (a commercial PDF editor, Preview) will surface the error if it does. Treat the tool as a value-entry layer, not a validating editor.
Can I fill multiple PDFs with the same data set?
The current tool processes one PDF at a time so the field-mapping UI stays focused. For a recurring template (e.g. a monthly invoice) keep the JSON value set in your notes and paste it back next month — every field name is identical run-to-run.
What happens to fields I leave blank?
Untouched fields retain whatever default value the form’s author set — usually empty string for text, unchecked for checkboxes, no selection for radio groups. The metrics panel reports how many fields you skipped so you can spot accidentally missed inputs.
Does it support digital signatures?
You can preserve existing signatures by NOT flattening the result; pdf-lib copies them through. To add a NEW signature, finish the fill, then chain the output into Sign PDF — that tool is purpose-built for signing and produces a cleaner output than trying to combine the two operations.
Can I see which fields the PDF actually has?
Yes — when you load the file, the tool lists every field with its name, type, current value, and any allowed options for radio/dropdown fields. The list is your source of truth for what is fillable.
Why is the upload limit 100 MB and not 200 MB like other PDF tools?
Form filling holds the parsed AcroForm tree in memory in addition to the source bytes. The 100 MB cap keeps mobile browsers stable; almost every real-world fillable PDF is well under that. Long PDFs (court filings, multi-page applications) almost always carry their fillable fields in the first few pages, so size is rarely the bottleneck.
Does the output PDF still print the way the original did?
Yes. Field appearances are regenerated using the same fonts the original PDF embedded, so a printed copy looks identical to a copy you would have produced by opening the file in any standards-compliant PDF viewer and printing from there.
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