SigPDF vs Fill.io — PDF Signing & Form Filling
Fill.io combines PDF form filling with e-signatures, targeting businesses that need to complete and sign forms. If your primary need is signing PDFs with maximum privacy, SigPDF is a lighter, more affordable option — starting at €2.08/month annually with files that never leave your device.
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SigPDF vs Fill.io: Feature Comparison
Fill.io (formerly Fill) is a cloud-based platform that focuses on PDF form filling and electronic signatures. It is popular with businesses that deal with government forms, tax documents, and standardized paperwork that needs to be completed and signed digitally. SigPDF focuses specifically on the signing aspect, processing everything in your browser without server uploads.
| Feature | SigPDF | Fill.io |
|---|---|---|
| Price | From €2.08/month (annual) | From $8.33/month (Pro annual) |
| Privacy | Files never leave your browser | Files uploaded to Fill.io cloud |
| Account required | No | Yes |
| PDF form field detection | No — manual text placement | Yes — auto-detects fillable fields |
| Multi-party signing | No (single signer) | Yes |
| Government form templates | No | Yes (IRS, USCIS, etc.) |
| Watermarks | Never | None on paid plans |
| Fax integration | No | Yes (online fax) |
Privacy: Documents Never Leave Your Device
Fill.io is a cloud platform that processes your documents on their servers. This is how they provide features like form field detection, template libraries, and multi-party signing. However, it means your PDFs — including any personal, financial, or medical information they contain — are transmitted to and stored on third-party servers.
SigPDF processes your PDF entirely in your web browser. The file is opened, edited, and saved using client-side JavaScript without any server communication. For tax forms, health records, legal documents, or any file with sensitive data, this provides a fundamentally higher level of privacy protection.
Pricing: More Affordable for Simple Signing
Fill.io's Pro plan starts at $8.33/month when billed annually, and their Business plan runs higher for team features. SigPDF starts at €2.08/month on an annual plan — less than a quarter of Fill.io's price. If you need to fill complex government forms with auto-detected fields, Fill.io's specialized features justify the higher cost. For signing PDFs, SigPDF provides the core functionality at a significantly lower price.
Form Filling vs. PDF Signing
Fill.io specializes in form filling — it can detect fillable fields in PDF forms, auto-populate information, and provide a library of government form templates. This is valuable for people who regularly complete standardized forms like tax documents or immigration paperwork. SigPDF focuses on signing: adding your signature, text, dates, and images to any PDF. With SigPDF, you can still type text anywhere on a PDF to fill in fields manually, but it does not auto-detect form fields.
When Fill.io Is the Better Choice
Fill.io is the better option if you frequently complete standardized PDF forms (tax documents, government applications, insurance claims), need auto-detected fillable fields, or want fax integration. Its template library and form-filling focus make it a specialized tool for paperwork-heavy workflows. For straightforward PDF signing with privacy as a priority, SigPDF is the more suitable tool.
Frequently Asked Questions
Can SigPDF fill in PDF form fields?
SigPDF allows you to add text anywhere on a PDF using the text tool, which works for manually filling in forms. However, it does not auto-detect or interact with built-in PDF form fields the way Fill.io does.
Is Fill.io secure for sensitive documents?
Fill.io uses encryption and security measures to protect documents on their servers. However, your files are still uploaded to and stored on third-party infrastructure. If you want to ensure your documents never leave your device, SigPDF's browser-based approach offers that guarantee.
Does Fill.io have a free plan?
Fill.io offers a limited free tier that allows a small number of documents per month. For unlimited usage and advanced features, paid plans start at $8.33/month (annual billing).