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How to Fill a PDF Form Online (Free, No Printing)

4 min readUpdated 5 October 2026

To fill a PDF form online, open Fill PDF Forms and drop in the form. Its fields are highlighted on the page: click one, type your answer, tick the boxes you need, then press Download filled PDF. If the form has no fields — a scan, for example — use Type anywhere and tap where each answer should go.

There's no printing, scanning or account, and it works the same on a computer, an iPhone or an Android phone. Forms are full of ID numbers, addresses and phone numbers, so it matters that this one is filled in inside your browser and never uploaded.

Do it now with Fill PDF FormsFree, no sign-up, works on any device.

Step by step

  1. 1Open Fill PDF Forms and add the formGo to the Fill PDF Forms tool and drop the PDF onto the page, or click to choose it. The file bar shows how many fillable fields it found.
  2. 2Fill in the fieldsClick a highlighted box and type, tick checkboxes, and pick answers from dropdowns and choice buttons. Required fields still empty have a red outline, and the side panel counts how many fields you've filled.
  3. 3Autofill your detailsOpen My details, enter your full name, email, phone, address and ID or passport number, then press Autofill to put them into the matching empty fields.
  4. 4Type on flat or scanned formsChoose Type anywhere, pick Text, Tick ✓, Cross ✗ or Date, and tap the page where it should go. Drag the grip beside an item to move it and use Text size to make it fit the line.
  5. 5Download the filled PDFSwitch on Flatten if the answers shouldn't be changed afterwards, then press Download filled PDF (or Ctrl/⌘ + Enter). The file is saved with “-filled” added to its name.

Fillable forms vs flat forms

A fillable form has real fields built in — you'll see Form fields with a count and highlighted boxes on the page. A flat form is just a picture of a form, such as a scan or a document exported without fields; the file bar says “No fillable fields” and the tool opens straight in Type anywhere.

On a flat form, Date adds today's date in one tap, in a format such as 05/10/2026, the Thai Buddhist year, or a written-out date. Tick ✓ and Cross ✗ are made for checkboxes printed on the page.

Tip: On a long form, type in Filter fields to jump to a field by name, or press the page number next to a field in the list to show it on the page.

Filling a PDF form on your phone

Open the tool in Safari or Chrome and choose the form from Files, Google Drive, Downloads or a file saved from LINE or email. Small boxes can be fiddly on a phone screen, so switch from On the page to As a list — every field gets a full-size box, switch or menu that's easy to tap.

When you tap Download filled PDF, the file goes to your Downloads (Files › Downloads on iPhone), ready to send back.

Should you flatten the form?

Flatten bakes your answers into the page, so they can no longer be edited as form fields. Use it for the final copy you submit. Leave it off if you might want to reopen the file and change an answer later — the tool reads back fields that are still there.

Answers in Thai or with special characters are drawn as sharp images in place, because the standard PDF font can't show them. Those particular fields stop being editable even without Flatten, and the tool tells you how many are affected.

If something doesn't work

The form won't open — it's password-protected. Unlock it first, then try again. The boxes look squeezed — some pages are rotated; fill those fields from the list instead. An XFA (dynamic) form — the standard fields are filled, but check the result in your PDF reader.

Signature fields are left as they are. Sign the filled form afterwards with Sign PDF. To start again, Reset puts the fields back as they were when you opened the file and removes anything you placed on the page.

After you've filled it in

A filled form usually needs one more step before you send it:

  • Sign PDF — add your signature and the date.
  • Merge PDF — attach supporting documents such as an ID copy.
  • Compress PDF — shrink it for email. Fill the form first: the stronger compression levels remove form fields.
  • PDF Editor — add notes, highlights or images anywhere on the page.

Questions people ask

Why can't I type into my PDF form?
The PDF probably has no fillable fields — it's a flat form or a scan. Choose Type anywhere and tap the page where each answer should go.
Can I fill a PDF form on my iPhone?
Yes. Open the tool in Safari, choose the form, fill the fields on the page or as a list, and download the filled PDF. There's no app to install.
Can I fill in a form in Thai?
Yes. Type Thai as usual. Thai answers are drawn as sharp images in place, so they look right in any PDF reader, but those fields can't be edited afterwards.
Are my personal details saved?
Only if you switch on Remember my details, and then only in this browser on this device. The form itself is never uploaded.
Can I edit the form after downloading it?
Yes, if you didn't flatten it: open the filled PDF again and the fields keep your answers. A flattened copy can't be changed as a form.
Do it now with Fill PDF FormsFree, no sign-up, works on any device.

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