See every field the form contains
After you add the file, the page asks indox to read its form fields and lists them under Options. Each box carries the description the form's author gave the field, or the field's internal name when there is none.
No file open
Fill PDF Form
or drop a file anywhere here
Dropbox
Google Drive
Files other than PDF are converted first. Signing in raises the size limit.
Or start from a blank IRS form
Browse all IRS forms →- You add
- One PDF with form fields
- You set
- Your answer for each field
- You get
- The same PDF with fields filled
A fillable PDF carries form fields: text boxes, tick boxes and choice lists that sit on top of the page. Fill PDF Form reads those fields from your file and shows them as a list you complete in the browser. Add one PDF, wait while the page reads its fields, type your answers and press Run Fill PDF Form. The download is your PDF with the values written into its fields. The fields stay live, so an answer can still be changed later. A single form runs without an account. The tool works only with fields that already exist in the file. It cannot type onto a scanned paper form, and it cannot complete a signature field.
What can you do when you fill a PDF form?
Start from the answers already there
A value saved in the PDF appears in its box, so a half-completed form opens where it was left. Type over a value to replace it.
Tick boxes and pick from lists
Checkbox fields appear as tick boxes. A field with a fixed set of options appears as a text box that suggests those options while you type.
Keep the form editable
The tool writes your values into the fields and leaves the fields in place. Run Flatten PDF on the filled form when the answers must not change.
What filling a form keeps and what it changes
Stays the same
- The form stays fillable, because no field is flattened or removed.
- A field you leave blank keeps the value the file already has.
- Read-only fields and signature fields, which are not changed.
- The page layout and content, since only field values are edited.
Changes
- Each answer you type is written into the matching form field of the PDF.
- The PDF asks the viewer to redraw the field appearances so the new values show.
- You download a new PDF. The copy on your device keeps its old answers.
How to fill a PDF form in 3 steps
Add the fillable PDF
Drop your fillable form on the upload box, or press Choose file. A short note says the page is reading the form fields in the PDF, and then the list appears.
Type your answers
Work down the list under Options. Fill the text boxes, tick the checkboxes that apply and skip any field you do not need.
Run the tool and download the form
Press Run Fill PDF Form, then choose Download once the filled PDF is ready. Open it and read each answer before you send the form on.
Why fill a PDF form with indox?
Fill PDF Form builds its list from your file, not from a fixed template, so the boxes you see are the fields that form really has. You do not install a PDF editor, and you do not hunt for fields on the page. The fill page is also clear about what it skips. Signature fields show a note saying they cannot be filled here, read-only fields are disabled, and a PDF without fields gets a plain message instead of an empty form. A single form needs no account. indox receives the form over HTTPS, and free-tier uploads and filled copies are deleted automatically within 24 hours after the fill job finishes.
- Fields read from your own PDF
- Saved answers loaded into the list
- Fields stay editable after the fill
- One form without an account
- HTTPS transfer, 24-hour free-tier deletion
What are the limits when you fill a PDF form?
- Size
- The free tier has a file size limit. Signing in raises it, and paid plans raise it further.
- Formats
- This tool works on PDF files. To change a file's type, use the PDF converter.
- Privacy
- Files are encrypted in transit and processed on indox infrastructure.
- Deletion
- Free-tier files are deleted automatically within 24 hours after the job finishes. Signed-in output stays in your history for your plan's retention period.
Limits worth knowing
- The tool fills fields that already exist. A scanned paper form, or any PDF without form fields, gets the message that it has no fillable form fields, and nothing can be typed onto it here.
- Signature fields cannot be filled on this page. Each one is listed with a note and left as it was.
- You fill a list, not the page. There is no page preview, and a field whose author gave it no description appears under its internal name, which can be hard to recognise.
- Clearing a box does not clear the field. Blank boxes are not sent, so a value that was already in the PDF stays there. The page also does not mark or enforce required fields.
- Tick boxes are saved as Yes or Off, and the page has no radio button control. A form that names its checked state differently, or that uses groups of radio buttons, may not fill correctly, so check those answers in the download.
When the result is not what you expected
| What you see | Why | What to do |
|---|---|---|
| The page says the PDF has no fillable form fields | The file has no form fields, which is common for scanned paper forms | This tool cannot add fields. Place text on the page with Add Stamp or look for a fillable version of the form. |
| The viewer asks to save changes when you close the file | The tool asks the viewer to recompute how the fields look, and pypdf's documentation says this can trigger a save prompt | The prompt is expected. To fix the answers in place, run Flatten PDF, which also makes the text unselectable. |
| A viewer still shows empty fields or old values | Some forms keep an XFA description, and pypdf's documentation says that form overrides the page content | Open the download in a second viewer. If the form is XFA-based, check the answers there. |
| A tick box is not ticked | Tick boxes are saved as Yes or Off, and the page has no radio button control | Check those answers in the download, and fix any that did not take in a PDF viewer. |
| A field you cleared still has its old value | Blank boxes are not sent, so the old value stays | Type a replacement over it. |
What do the free and paid plans add?
Free
- All converters
- Daily credit refresh
- Email support
Basic
- Access to all features
- AI Extract
- Priority conversions
- Email support
Highest priority
Premium
- Everything in Basic
- Highest priority queue
- Larger file limits
- Priority support
Pay-As-You-Go
- No subscription
- Credits never expire
- Opt-in auto-refill
- Access to all features
What else can you do with a PDF?
Who fills PDF forms online?
Applicants and tenants
A landlord, school or employer sent a fillable PDF and you have no PDF editor. Type your details into the list and send back the filled form.
Office staff with recurring forms
A supplier form or internal request comes round again with mostly the same answers. Upload the last copy, change the few values that differ and download the new one.
People on a phone or shared computer
You cannot install software where you are. The field list opens in the browser, so the form can be completed on the device at hand.
When to fill a form here, and when to pick another tool
- An application form arrived as a fillable PDF and you need to return it completed.
- A partly completed form needs two or three of its answers corrected.
- You want to fill in some fields before you pass the form to a colleague to finish.
- You need to see which fields a PDF form actually contains before you build a process around it.
- The answers must be locked once the form is filled. Run Flatten PDF on the result, because this tool leaves every field editable.
Where can I read more?
Sources
- Interactions with PDF Formspypdf documentation
- The PdfWriter classpypdf documentation
Facts checked on October 16, 2026
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Fill PDF Form FAQs
How does the tool know which fields my PDF has?
After you add the file, the page sends it to indox, which reads the form fields stored in the PDF and returns their names, types and current values. The list under Options is built from that answer.
Why does the page say my PDF has no fillable form fields?
The file contains no form fields. That is common for scanned paper forms and for PDFs saved without interactive fields. This tool cannot add fields or type directly on the page.
Can I fill a signature field with this tool?
No. Signature fields appear in the list with a note that they cannot be filled here, and the tool leaves them untouched.
Will the form still be editable after I download it?
Yes. The tool writes values and keeps the fields live. To fix the answers in place, run the filled form through Flatten PDF, which also makes the page text unselectable.
Why is a field disabled in the list?
The form marks that field as read-only, so the page disables its box and sends no value for it. Unlock Forms is the tool for making locked fields editable again.
How do I clear an answer that is already in the form?
You cannot clear it on this page. An empty box is skipped when the fill runs, so the old value stays. Type a replacement over it instead.
Do I need an account to fill a PDF form?
No. Fill PDF Form has the free badge, and one form runs without signing in.
What happens to the form I upload?
It travels to indox over HTTPS. On the free tier, the uploaded form and the filled copy are deleted automatically within 24 hours after the job ends.