A form arrives by email — an application, an intake questionnaire, a waiver. You download it, click into the first blank, and one of two things happens: a cursor appears and you type, or nothing happens at all and you're left looking at a page that refuses you. Which of the two you get depends on how the PDF was made, and both cases have a solution that doesn't involve Adobe.
For a decade the reflex was "open it in Acrobat" — or worse, print it. Neither is necessary anymore. PDF Forms detects the fields your PDF already contains and lets you fill them right in the browser, and the flat, fieldless kind of form has a workaround of its own. Nothing gets uploaded at any point.
Two kinds of PDF form — and how to tell them apart
Fillable forms were built with fields: text boxes, checkboxes, radio buttons, dropdowns embedded in the file. When you click a blank, your PDF reader highlights it and accepts typing. Tax forms, applications, and anything generated by a form tool usually work this way.
Flat forms are just printed pages — a Word document or a scan exported to PDF, with lines and boxes drawn on it but no fields behind them. Clicking does nothing, because there's nothing to click: the blanks are ink, not inputs. Older documents, scanned paperwork, and forms designed for handwriting land here.
The quickest test is to click a blank in whatever viewer you have. A highlight or cursor means fillable; silence means flat. The two kinds need different approaches, and the rest of this guide covers both.
How to fill out a PDF form
- Open PDF Forms and drag in your file — up to 100 MB.
- Fill in the fields: type into text fields, tick checkboxes, select radio buttons and dropdowns.
- Add a signature if the form needs one — or leave that option off if it doesn't.
- Download the filled PDF.
Text fields, checkboxes, radio buttons, and dropdowns are the supported types, which covers the overwhelming majority of real-world forms. If the form asks for a signature, that's built into the same flow — draw, type, or upload it — so you're not sent hunting for a second tool halfway through. And because everything happens locally, the half-filled form with your personal details in it never leaves your machine.
What if the PDF has no fillable fields?
Here the honest limitation comes first: PDF Forms only fills fields that already exist in the PDF — it doesn't add new form fields to a plain document. If the tool finds no fields, you can still add a signature, but the typing blanks of a flat form aren't something it can invent.
The workaround for flat forms is to place text over them instead of into them. Edit PDF adds text boxes on top of the page, so you can type your answers and position them over the printed blanks — one text box per field, lined up with the lines on the page. It's a little more manual than real fields, but it produces a clean, typed result on a form that was never meant to be filled digitally. The full walkthrough for that approach is in How to Add Text to a PDF Without Acrobat.
Adding a signature to the form
Plenty of forms end with a signature line, and adding one is optional — leave "Add a signature" unchecked and just fill the fields if yours doesn't. When a form does need one, the same disclosure applies here as everywhere on this site: the result is a visual signature image, not a certified, legally binding e-signature under eIDAS or the U.S. ESIGN Act, with no audit trail or certificate. For forms where legal certification matters, use a dedicated e-signature service. For the ordinary paperwork of daily life, it's exactly what's needed.
Flattening after you fill
Filled fields are, by design, still editable — anyone with a PDF editor can change what you typed. That's sometimes the point (a form that goes back for corrections), and sometimes a problem (a completed form going out as final). For the second case there's Flatten PDF: flattening renders each page — including the form field values — into a static image, so everything is baked into the page content and can't be edited.
Know the trade before you use it. Flattened pages are images, which means the text on them is no longer selectable or searchable. The practical habit: flatten a copy for sending, and keep the original with live fields for yourself. If you need the text searchable later, the original is what you search.
Why you don't need Adobe anymore
Adobe Reader filled in forms for free for years, and "download Adobe" became muscle memory. But Reader was a piece of desktop software you installed and kept updated to do something a browser tab can do now — and the fuller toolkit around it pushed accounts and subscriptions for jobs like editing that browsers also handle today.
The browser-based alternative has one structural advantage worth ending on: your form — with your name, address, and ID numbers on it — is processed by the page you have open, on your device, and never uploaded. Filling a form is the moment a document is at its most personal. Doing it without a server in the middle isn't a niche feature; it's the sensible default.