PDF Form Filler

FORM PDF PRIVACY

About this tool

Fill + save any PDF form

Open any AcroForm PDF, fill text fields, checkboxes, dropdowns. Save with values or flatten to non-editable.

RT-IMG-022 · Image & File

Drop a PDF form here or click to choose Detects AcroForm fields and lets you fill them in your browser

No PDF loaded yet.

💡 Editable vs flattened: "Editable" preserves the form fields so the recipient can still change values. "Flattened" bakes the values into the page content stream — the result is a regular non-editable PDF, ideal when you want to send a finalised, locked-in copy that nobody can tamper with.

Drop a PDF to begin.

🔒 Forms stay on your device. All field detection, editing, and saving happens entirely in your browser using the self-hosted pdf-lib library. Nothing is uploaded — verify in DevTools → Network.

How to fill a PDF form online

Add your PDF form

Drop a form-bearing PDF onto the dropzone. The tool scans the document's AcroForm dictionary and lists every interactive field — text inputs, checkboxes, dropdowns, radio buttons, and multi-select lists — with the field name and detected type tagged.

Fill in the values

Each field shows up with its current value pre-filled (if any). Type into text fields, tick checkboxes, choose from dropdowns. The form respects field metadata — text fields show the declared maxLength, dropdowns show only their valid options, radio groups enforce single-select.

Save editable or flattened

Save filled (editable) writes your values into the form fields and downloads a PDF that the next person can still edit. Save flattened bakes the values into the page content stream — fields disappear, values become regular printed text. Flattened files are perfect for sending finalised forms.

Signature fields stay untouched

Digital signature fields are detected but not editable in the browser — they require cryptographic signing, which is a separate workflow. The tool leaves signature fields blank so you can finish them in Adobe Acrobat, DocuSign, or your jurisdiction's e-signature platform.

PDF forms — the format your bank, your government, and your employer rely on

The PDF AcroForm — Adobe's interactive form spec, baked into the PDF standard since 1996 — is the format every bank application, tax return, employment form, school admission, and immigration document quietly runs on. You download a PDF, fill it in, save, email it. That round-trip happens billions of times a year. And yet most users do it through one of three tools: Adobe Acrobat (expensive), a browser PDF viewer (which often saves badly), or a sketchy "free online PDF filler" website (which uploads your filled form to their servers along with whatever sensitive data you typed in).

What's actually inside a PDF form

A PDF form is a regular PDF with an extra dictionary called /AcroForm in the document catalogue. That dictionary lists every interactive field with its name, type, position, default value, and validation rules. When you "fill" the form, you're setting the value of each named field; when you save, those values are written back into the same field objects. The page itself doesn't change — the form fields are an overlay rendered on top by the PDF viewer.

A PDF form is a PDF with a hidden field-overlay layer. Filling it changes the field values, not the page content — which is exactly why "flattening" exists: it bakes the overlay into the page so the result is a normal locked PDF.

The APAC document-form economy

PDF forms are central to Singapore's IRAS tax workflows, CPF declarations, ICA immigration applications, and SingPass-issued government forms; Malaysia's LHDN tax filings and EPF withdrawal forms; Indonesia's OJK financial declarations; Vietnam's SBV banking forms and corporate registration filings; the Philippines' BIR (Bureau of Internal Revenue) forms; Thailand's revenue department forms; and Hong Kong's SFC and Immigration Department forms. Across the region, a clean browser-side filler is a privacy upgrade over the alternative of uploading half-completed government forms to a foreign SaaS.

Editable vs flattened — the choice that confuses everyone

"Editable" means you save the PDF with the form fields still interactive — your values are filled in, but the next person who opens the PDF can edit them. That's appropriate when you're handing the form to a collaborator to add their bits. "Flattened" means the fields are removed and your values are converted into regular printed text on the page. That's the right choice when you're submitting the final form to someone who shouldn't be able to alter it — your bank, your employer, the tax office. A common mistake is sending an editable PDF to the tax office; they receive it, "fix" a number, and now there's a dispute about which version is canonical. Flatten before you submit.

10 Things to Know About PDF Forms

AcroForm — Adobe's interactive PDF form spec — has been part of the PDF standard since version 1.2, released in 1996. It predates the modern web and outlived every alternative.

The competing PDF form standard is XFA (XML Forms Architecture), used by some Adobe LiveCycle workflows. XFA is being deprecated and isn't supported by most modern PDF tools — including this one.

Every form field has a unique name (often hierarchical like person.address.street) that the underlying PDF refers to. Field names matter — they're what determines where your typed text actually lands.

"Flattening" a form converts every field into regular page text and removes the AcroForm dictionary. The resulting PDF can no longer be filled in — but it's also significantly smaller and renders identically everywhere.

The PDF/A archival standard (used by governments for long-term records) generally forbids interactive form fields — every PDF/A archival submission is a flattened copy.

Many form-bearing PDFs from old Adobe LiveCycle workflows are technically XFA, not AcroForm. They look identical in Acrobat but won't expose any fields to pdf-lib or browser tools.

Digital signatures in PDFs use the PKCS#7 cryptographic standard — totally separate from form filling. A PDF can have signature fields, filled fields, and flattened content all in the same document.

Checkboxes in PDFs aren't booleans — each has a named "on" state (often "/Yes" but sometimes "/0" or arbitrary strings). pdf-lib normalises this for us so checkboxes behave the way you'd expect.

Form fields can have JavaScript actions attached — "validate this email," "calculate this total." Browser tools strip these on save, which is usually fine; if the form depended on them, fill in Acrobat instead.

The pdf-lib library used here is MIT-licensed, runs entirely in-browser, and supports text, checkbox, dropdown, option list, radio group, and signature field types — covering 99% of real-world PDF forms.

FAQ

No. pdf-lib runs entirely in your browser. The PDF is read into memory, edited in memory, and saved back to your downloads. Open DevTools → Network and watch — there's zero outbound traffic during the entire flow.
The PDF has no AcroForm dictionary — it's a regular flat PDF without interactive form fields, or it's an XFA-only form (used by some Adobe LiveCycle workflows) which browser tools can't read. Open it in Adobe Acrobat: if you can click into fields and type, it has AcroForm fields; if everything is read-only, there are no fields to fill.
Editable = form fields stay interactive, your values are written into them, recipient can still change values. Flattened = fields are removed and your values become regular page text. Use editable for collaborator hand-off, flattened for final submission.
No — digital signature fields require cryptographic signing with a certificate, which is outside the scope of this tool. Signature fields are detected but left blank. To sign, use Adobe Acrobat Reader (free), macOS Preview, DocuSign, or your jurisdiction's e-signature platform (SingPass / MyKad / etc.).
Text inputs, checkboxes, dropdowns (single-select), option lists (multi-select), and radio groups. Signature fields are detected as read-only. Date and image fields are treated as text and signature respectively, matching pdf-lib's classification.
Browser tools strip JavaScript actions on save. For most forms this is fine — but if the form had "calculate total" or "validate ID" actions, those won't run here. Fill those forms in Adobe Acrobat Reader instead, which executes the embedded JavaScript natively.
Yes — pdf-lib preserves the page content, layout, fonts, and images exactly. Only the form-field values change. Flattening replaces the field overlays with text drawn in the field's declared font and position, matching what Acrobat would render.
Restriction-only protection (no-print, no-edit) is bypassed via pdf-lib's ignoreEncryption flag. Open-password protection is not — you need to remove the password first via Adobe Acrobat or macOS Preview.
Some PDF authors don't bother naming fields, so you see things like Text1, Form1[0].Page1[0].Cell[0], or random IDs. The type tag (TEXT / CHECKBOX / etc.) and current value usually give you enough context to identify which form-paper field each one corresponds to. Open the source PDF side-by-side for reference.
Three reasons: (1) prevents the recipient from changing your answers, (2) reduces file size (form-field overlays are removed), (3) ensures the form renders identically in every viewer — including ones with weak AcroForm support. Always flatten before submitting forms to government, banking, or HR portals.

PDF Form Filler