Fill in a PDF form on your Mac without uploading it
By Himanshu Ranjan · Updated 8 November 2026
To fill a PDF form on a Mac with FileDial, select it in Finder, hold the right Option key and choose Sign & Lock › Fill form… Type into the form's fields and FileDial saves a new copy. If the form has no fields, Make PDF fillable turns empty boxes and blank lines into text fields first. Flatten forms locks your answers in. Nothing is uploaded.
How to do it with FileDial
- Select the PDF form in Finder.
- If it has no clickable fields, hold right ⌥ and choose Sign & Lock › Make PDF fillable.
- Hold right ⌥ and choose Sign & Lock › Fill form…, then type your answers.
- Choose Sign & Lock › Flatten forms on the filled copy before sending.
Your original file stays untouched. The result is saved beside it, and every result has Undo.
Which option to pick
| Tool | Use it when |
|---|---|
| Fill form…Sign & Lock | The form has fields: type into them and a new copy is saved. |
| Flatten formsSign & Lock | Finished filling: fields become plain page content, so answers can't be casually changed. |
| Make PDF fillableSign & Lock | A flat form with boxes and lines: they become text fields, as a best guess. |
Fillable, flat and flattened forms
PDF forms come in two kinds. A fillable form has interactive fields you can click and type into; a flat form is just a picture of boxes and lines, often a scan or a document exported without fields. Fill form… works on the first kind. For the second, Make PDF fillable looks for empty boxes and blank lines and turns them into text fields. Its note calls this a best guess, so check that every field landed in the right place before you rely on it.
Flattening is the step people forget. A filled but unflattened form still has live fields, so the next person can edit your answers, and some viewers display field contents differently or not at all. Flatten forms converts fields into ordinary page content, which looks the same everywhere. Keep an unflattened copy if you might need to change an answer later; FileDial's new-copy approach makes that automatic.
Before filling, check whether the organisation needs a specific version of the form, and whether a signature is required. For signatures, see signing a PDF.
- Government and tax forms: usually fillable; fill, then flatten.
- Scanned paper forms: Make PDF fillable, then fill.
- Forms that need a signature: fill, sign, then flatten.
Why not fill forms on a website?
Forms ask for the most sensitive details people have: identity numbers, dates of birth, bank details, income. That is the very data the FBI Denver Field Office warned in March 2025 that free online document tools can scrape, along with emails and passwords. The same warning notes returned files can carry malware leading to ransomware.
And once uploaded, files can sit in storage you can't see: Cybernews reported in July 2024 that two PDF services exposed 89,062 user files, including passports and IDs. FileDial fills forms on your Mac, offline.
Other ways to fill a PDF form on a Mac
Preview fills interactive forms well: open the PDF, click a field and type. For flat forms, Preview's markup tools let you add text boxes and position them over the lines yourself. Both are free and fine for a single form.
FileDial helps when a flat form needs real fields, when you want a clean flattened copy for submission, or when you prefer each stage saved as its own file with Undo, leaving the blank original untouched.
Questions
Can I fill a PDF form that isn't fillable?
Yes. Run Sign & Lock › Make PDF fillable first. It turns empty boxes and blank lines into text fields as a best guess, then you can use Fill form…
What does flattening a form do?
Flatten forms turns fields into plain page content. Your answers look the same in every viewer and can't be casually edited by the next person. Keep an unflattened copy if you may need changes.
Will my blank form be overwritten?
No. Fill form… saves a new copy, and the original stays blank beside it. That makes it easy to fill the same form again later, for example next year's version of a recurring application.
Does it work offline?
Yes. Every FileDial tool runs on your Mac and works with Wi-Fi off. Your answers and the form are never uploaded, so identity and bank details stay on your Mac.
Is FileDial free?
It has a 1-day free trial with every tool, no card and no account. After that it is $20 once for a lifetime licence on 2 Macs, with a 14-day refund.