How to Create and Fill a PDF Form

A PDF form is a document with real fields on it: text boxes, checkboxes, dropdowns, radio buttons — the kind a recipient can fill without printing anything. There are two separate jobs here, and mixing them up is the usual cause of trouble. Creating a form means placing the fields; filling a form means typing values into fields someone else placed. This guide walks both, and the three steps that come after either one: checking what fields exist, moving the values in or out, and locking them so every viewer sees them. It belongs to the sign and fill family; for putting a signature on the finished document, the sequence is in Sign a Contract and Return It.

Which tool should I use?

Form Builder creates fields from scratch, Edit Form Fields changes them, and Fill completes a finished form. The four tools split along that line:

Job	Tool	Where it runs
Design a new form with fields	create a fillable PDF form	Browser, free, no upload
Change existing fields — rename, required, options, delete, read-only	edit PDF form fields	Browser, free, no upload
List every field and its current value	inspect PDF form fields	Browser, free, no upload
Type values into a finished form	fill a PDF form	Browser, free, no upload
Move values out as JSON, FDF, or CSV, or refill from JSON	PDF form data import/export	Browser, free, no upload
Bake the values into the pages so they display everywhere	flatten a PDF	Browser, free, no upload

All of them run in your browser with no account and no upload, and all of them work on interactive AcroForm fields — the field model is explained in one paragraph on the form field glossary entry. If a “form” you received has no fields at all, it is a flat document: somebody exported it without the fields, and the first step is to place them with the form builder.

How do I create a fillable PDF form?

1. Prepare the layout first. The fields sit on top of a document, so have the document ready — a PDF of the form’s static parts: headings, labels, lines, and instructions. Start from create a PDF from scratch or from the ready-made consent acknowledgement form template, which arrives with the fields already placed if you want to skip ahead.
2. Open the form builder. Go to create a fillable PDF form — no account, nothing uploaded.
3. Place each field. Add text fields, checkboxes, dropdowns, and signature placeholders, positioned on the page where each label expects its answer. The builder writes real AcroForm dictionaries, entirely in the browser.
4. Set the field properties. Mark the fields that must be filled, give dropdowns their option lists, and name each field something recognizable — field names are what you will see when you export or refill values later.
5. Export the form. Save the result. Test-fill it once yourself: a form you have never filled always surprises you with a field that is too small for the answer it asks for.

A concrete example: a consent acknowledgement that every participant must sign and return. One page, five fields — full name, email, date, an “I have read and agree” checkbox, and a signature text field. Build it once, and every participant after that fills their own copy in their own browser; the full receive-and-return sequence is in Collect Signed Consents.

How do I fill a PDF form?

1. Open the fill tool. Go to fill a PDF form — no account, no upload.
2. Load the form. The tool auto-detects the interactive fields. If it finds none, the file has no fields — check with inspect PDF form fields to see whether the fields are missing or merely read-only.
3. Fill the fields. Type into text fields, tick checkboxes, select radio buttons. Values stay in your browser.
4. Choose the export shape. The default is a flattened file, where the values are baked into the pages and no longer editable. Choose the fields-still-editable export if you — or the next person — need to keep working on it.
5. Download and check. Open the result and confirm every value landed where its label expected. Empty and misaligned fields are the most common reason a submitted form gets returned.

If you fill the same form repeatedly, or you have the values in another system, PDF form data import/export skips the typing: it moves every field’s value out as JSON, FDF, or CSV, and refills the whole form from a JSON file.

How do I check what fields a form has?

Before you send a form to anyone, run inspect PDF form fields. It lists every field with its name, type, current value, and read-only state, so you see the form the way a machine sees it rather than the way it looks on the page. Two specific problems show up only in that list: fields with duplicate names (which share one value across the document), and fields marked read-only that nobody can fill. Rename duplicates with edit PDF form fields before distribution — a duplicate name is exactly how one person’s answer appears in two places at once.

How do I lock the values so they display everywhere?

Some viewers ignore form fields, which means a filled form can arrive showing empty boxes even though the values are inside the file. Flatten a PDF merges the fields into read-only page content: the values become part of the page, so they display in any viewer, and they cannot be edited in transit. Flattening is irreversible, so keep the unflattened original — this is the one way to lose a fillable form, and it is the only step in the whole workflow with no undo.

The standard order for a form that goes out finished: fill → check → flatten. Keep the unflattened copy if values might change; flatten when the values are final and the file leaves your control.

What about signatures?

A signature is not a field-filling step, and it runs after the values are in place. Two tools, two different jobs:

• sign a PDF — browser, free, no upload — places your signature on the page.
• sign a PDF with a digital certificate — runs PAdES signing on PDFLean’s encrypted cloud path and uses plan quota. When somebody later needs to check what the signature says, verify a PDF signature reports the certificate, the signer, and whether the document changed after signing.

Which one applies to your document is set by whoever receives it. The full read-fill-sign-return sequence, and what each step protects, is in Sign a Contract and Return It.

Frequently Asked Questions

Do I need an account to create or fill a form? No. Creating, filling, inspecting, data import/export, and flattening all run in your browser, free, with no upload. Only the PAdES signing tool needs an account and uses plan quota.

My form shows fields on the page but the fill tool finds none. Why? The visible lines and boxes are probably drawn artwork, not interactive fields — the document was exported without its field layer. Recreate the fields with create a fillable PDF form or edit PDF form fields on top of the drawing.

Can I fill a form on my phone? Yes — these tools run in the browser, so any device with a modern browser works. Browser support details are on the browser compatibility reference page.

Can I save the values and refill a fresh copy later? Yes. Export the values with PDF form data import/export, then refill any blank copy of the same form from that JSON. The values follow the field names, so the form has to keep its names stable between versions.

What is the difference between flattening and making a field read-only? Read-only keeps the field: the value stays in the field and the field cannot be filled, but the structure is unchanged, so a viewer that ignores form fields still shows an empty box. Flattening removes the field entirely and writes the value into the page, so every viewer displays it — at the cost of the form no longer being fillable by anyone. Choose read-only to lock pre-filled content while filling continues; choose flattening when the values are final and the file leaves your control.

What does “read-only” mean on a form field? The field carries a value but cannot be edited by filling. It is set deliberately for pre-printed information, and it is also how a broken form arrives. The inspection tool shows the state of every field in one list.

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The whole workflow is an ordering problem more than a tools problem: place fields before distributing, fill before signing, check before flattening, and keep an unflattened original. Everything up to the signature runs in your browser, and the one irreversible step — flattening — is the only one that needs a backup copy.

Do It Directly

Ready to build or fill the form in front of you? Create a fillable PDF form to place fields, fill a PDF form to type the values, inspect PDF form fields to see what is really there, and flatten a PDF to lock the values for distribution. Starting from a template? The free PDF templates page has ready-to-fill forms.

Related reading

• Sign a Contract and Return It — the signature half of the job: read, fill, sign, return
• Sign and Fill PDF Forms — the family hub: every form and signature tool in one place
• Supported Formats — the formats the fill, sign, and flatten tools accept