Fill a PDF form, then flatten it.
Open a PDF, type into its fields, and download it — either still editable or flattened, so the values become part of the page and nobody can change them. The file is read and rewritten in this tab.
Drop a PDF form here
Its fields appear on the page as blue boxes you can type into. You can also paste a PDF from the clipboard.
The file is opened in this tab. It is never uploaded.
What the tool actually does
Every field, where it really is
Text fields, checkboxes, radio groups, dropdowns and option lists are drawn over the page at the exact rectangle the PDF gives them, with their real field name, type and constraints in the panels.
Flatten, not just fill
Flattening bakes each field's appearance into the page content and removes the interactive form, so the next person to open the file sees fixed text instead of an editable box they can empty by accident.
Cyrillic that survives flattening
Values are re-rendered with a bundled Noto Sans before the form is flattened, which is why Cyrillic, Estonian and other non-Latin characters appear in the result instead of blanks or question marks.
The file never leaves the tab
The PDF is parsed with pdf.js and rewritten with pdf-lib inside your browser. There is no upload step, no account, no analytics — close the tab and nothing remains.
PDF forms, filled and flattened in the browser
A PDF form is a normal PDF with an extra structure inside it called an AcroForm: a list of fields, each with a name, a type and one or more widget rectangles that say where on the page it is drawn. FormFlatten reads that structure with pdf-lib, renders the pages with pdf.js, and places a real input, checkbox, radio button or dropdown over each widget — so you fill the form where it appears, not in a separate list. The left panel lists every field grouped by page with its exact PDF name, the right panel shows what the file says about the selected field: its type, font size, maximum length, whether it is required or read-only, and the tooltip the issuer wrote for it.
When you are done there are two ways out. “Filled PDF” writes your answers back into the form and keeps it interactive, which is what you want when someone else still has to add their part. “Flattened PDF” generates an appearance stream for every field, draws it into the page content and then deletes the form, so the document becomes ordinary page text: it prints identically everywhere, it survives being merged into other documents, and it cannot be silently edited or reset. A third option re-renders every page as an image for the rare recipient whose software chokes on anything interactive. All three run entirely on your device — the PDF, the values you type and the signature you draw never touch a server.
Guides & articles
How PDF forms are built, what flattening does, and how to fill official paperwork privately.
What is a PDF form? AcroForm vs XFA and why some forms won't open
A fillable PDF is an ordinary page with a second layer of objects on top. Here is what that layer contains, why the same file behaves differently in different readers, and what an XFA form is.
Why flatten a PDF form before sending it (and what flattening actually does)
Flattening turns your answers from editable field values into fixed page content. That changes how the file prints, how it merges, how it survives email — and it is irreversible.
Filling official forms privately: keep your ID numbers off other people's servers
A tenancy application or a tax form carries more identifying data than most database breaches. Here is what happens when you upload one to a free online filler, and how to avoid it.
Frequently asked questions
Is my PDF uploaded anywhere?
No. The file is read by JavaScript running in this tab — pdf.js draws the pages and pdf-lib reads and rewrites the form — and the download is generated in memory on your device. Nothing is sent to a server: there is no upload endpoint, no account, no analytics and no third-party script. You can confirm it by opening your browser's network panel while you fill and download, or by switching off your connection after the page has loaded — the tool keeps working.
What is the difference between the filled and the flattened download?
The filled PDF keeps the interactive form: your answers are stored as field values, and whoever opens the file can click into a field and change it. The flattened PDF draws each field's appearance into the page itself and then deletes the form, so the text is ordinary page content — it prints and renders identically everywhere and cannot be edited or reset without proper PDF editing software. Use filled when someone else still has to add their part; use flattened when you are sending the finished document.
Why can't the flattened file be edited again?
Because the fields no longer exist. Flattening converts each widget's appearance stream into a normal XObject drawn into the page's content stream, then removes the field objects and the AcroForm dictionary. What is left is text and vector drawing, exactly like the rest of the page — there is no field to click. That is the point of flattening, so keep the original PDF (or the filled version, or an exported JSON of your values) if you may need to change an answer later.
Will Cyrillic, Estonian or other non-Latin text survive flattening?
Yes. Most PDF forms declare a standard font such as Helvetica, which only covers WinAnsi characters — flatten such a form naively and Cyrillic values come out empty or as garbage. FormFlatten embeds Noto Sans (shipped with the site, not fetched from a font service) and regenerates every field's appearance with it before flattening, so the characters are really in the file. Emoji and rare scripts outside Noto Sans are still not covered and the tool will tell you if it hits one.
The tool says there are no fields, but the form looks fillable. Why?
Three common reasons. The form may be an XFA (LiveCycle) form, whose fields live in an XML payload that only Adobe software renders — FormFlatten shows a warning when it sees one. The file may be a scan or a print-to-PDF export, so the boxes are just lines drawn on the page. Or the fields may be hidden or have zero-size rectangles, in which case the panel says how many were skipped. In the first two cases use the text box tool: it draws text straight onto the page wherever you place it.
Does a drawn signature count as a legal signature?
It is an image of your handwriting placed in the document — the digital equivalent of signing a printed page, and many organisations accept exactly that. It is not a cryptographic digital signature: it does not certify who signed or prove the document has not changed since. If the recipient asks for a qualified electronic signature (eIDAS, Smart-ID, Mobile-ID, a certificate from your ID card), sign the flattened PDF with that service after downloading it here.
How large a PDF can I open?
The tool accepts files up to 60 MB. Everything happens in the tab, so the real limit is your device's memory: a 60 MB scanned form with hundreds of pages will be slower than a 300 KB government form with twelve fields. Pages are rendered only as you scroll to them, which keeps long documents usable. The rasterised download is the heaviest operation because every page is re-rendered as an image.
When should I use the rasterised download?
Only when the recipient's software mishandles the normal flattened file — some old kiosk printers, scanning workflows and document management systems still do. Rasterising re-renders every page as a JPEG image at about 144 dpi, which guarantees the page looks the same everywhere but makes the file larger, removes selectable text and drops any accessibility information. Try the ordinary flattened PDF first.
Does it work on a phone?
Yes. On small screens the page fills the width and the field list and properties open as panels from the bottom bar. Fields are real inputs, so the phone keyboard, autofill and text selection behave normally, and you can sign with a finger. Very large scanned PDFs may be slow on older phones — that is a memory limit, not a missing feature.