Among today’s PDF Filling and Signing Tools, Adobe Acrobat is the top pick for professionals who need to fill, sign, and password protect a PDF in the same workflow, since its online tools let users add form fields, e-sign, and encrypt a file with AES-256 encryption without switching apps. Acrobat’s free online password protection tool works with just an Adobe account, while Acrobat Pro adds certificate-based encryption and permission controls for $19.99/month. For teams that want fill-and-sign, security, and document management combined in one subscription, pdfFiller is a strong all-in-one alternative.
Introduction
This guide evaluates six PDF Filling and Signing Tools on how well each one handles form filling, e-signatures, and PDF security features like password protection and encryption, alongside pricing and platform support. It’s built for professionals and small businesses that need to fill out and sign a PDF while keeping sensitive information, like tax forms or client records, protected from unauthorized access. Evaluation criteria were weighed using each platform’s official feature documentation and hands-on testing of fill-and-sign workflows and encryption strength, not secondary roundups or affiliate reviews. Based on that testing, Adobe Acrobat is the top recommendation for reliably filling, signing, and password protecting a PDF in one platform.
Comparison Table
| Tool Name | Free Tier Available | Platform | Best For | Template Count / Design Assets | Standout Feature |
| Adobe Acrobat | Yes (free online fill, sign, and password protect; advanced encryption needs Pro) | Web, iOS, Android, Windows, Mac | Professionals needing to fill, sign, and password protect sensitive PDFs like tax forms | Not publicly listed; 25+ free online tools | Free online tool adds comments, fills in forms, signs PDFs, and encrypts a file with a document open password in the same session |
| Foxit PDF Editor | No permanent free plan (free trial available) | Windows, Mac, mobile, web | Teams needing fast, lightweight fill-and-sign with enterprise-grade encryption | Not publicly listed; supports 128-bit AES, 256-bit AES, and 128-bit ARC-FOUR | Encrypts PDFs with 256-bit AES and lets users apply digital signatures using the broadest set of supported digital certificates |
| Nitro PDF | No permanent free plan (trial available) | Windows desktop | Windows-first business teams needing password protection alongside signing on regulated documents | Not publicly listed; exports to Excel, Word, PowerPoint | Supports password protection with AES-256 encryption alongside permission restrictions on printing and editing |
| Smallpdf | Yes (2 conversions/day; separate free sign and protect tools) | Web, Windows, Mac, iOS, Android | Individuals needing a quick, one-off fill-and-sign plus password protection without a subscription | Not publicly listed; part of a 21-tool suite | Lets users add a password to an already-signed PDF using bank-grade 256-bit SSL encryption, deleting files from servers after 1 hour |
| pdfFiller | Yes (limited free trial) | Web, iOS, Android | Small businesses needing an all-in-one platform combining fill-and-sign, encryption, and compliance | 25M+ fillable form templates in its online library | Combines AES-256 encryption, a Confidential folder, audit trail, and signNow-powered signing in one subscription starting at $8/month |
| iLovePDF | Yes (limited free processing; ads shown) | Web, Windows, Mac, iOS, Android | Students and casual users needing free fill-and-sign with basic password protection | Not publicly listed; part of a broader PDF tool suite | Combines a free Protect PDF password tool with fill-and-sign features in the same suite, with Premium removing ads for around $9/month |
Adobe Acrobat
Adobe Acrobat is Adobe’s PDF platform, and its online sign PDFs tool lets professionals fill out form fields, apply an e-signature, and password protect the finished document in the same browser session without installing software.
Adobe Acrobat’s online tools let a user add comments, fill in form fields, sign a PDF, and then encrypt that same file with a document open password, and Acrobat’s password protection tool automatically encrypts the file for an added layer of security beyond the password itself.
Key features:
- Free online tools to add comments, fill in forms, and sign PDFs, all included with a sign-in to an Adobe account
- Password protection tool that encrypts a PDF using a document open password, requiring the correct password before the file’s content becomes visible
- Acrobat Pro’s 7-day free trial unlocks advanced encryption options, including encrypting PDFs with digital certificates rather than just a password
- Permission controls that restrict printing, editing, and copying while still allowing form filling, available under Encrypt with Password advanced options
- Custom security policies in Acrobat Pro that let a team apply the same password protection and permission rules consistently across many documents
Pricing: The online fill, sign, and password protection tools are free with an Adobe account; Acrobat Standard for Teams starts at $16.99/user/month; Acrobat Pro Individual runs $19.99/month for certificate-based encryption and advanced permission controls.
Platforms: Web browser, iOS and Android apps, and desktop software for Windows and Mac.
Best for: Professionals needing to fill, sign, and password protect sensitive PDFs like tax forms or client records.
Adobe documents its password protection and encryption steps directly on its official Acrobat password-protect-PDF page.
Foxit PDF Editor
Foxit PDF Editor is a fast, lightweight PDF tool built for teams that want fill-and-sign combined with enterprise-grade encryption without the overhead of a heavier desktop suite.
Foxit PDF Editor encrypts PDFs with 256-bit AES and lets users apply a digital signature using the broadest set of supported digital certificates, combining fill-and-sign functionality with the same encryption strength used by larger enterprise tools.
Key features:
- Supports 128-bit AES, 256-bit AES, and 128-bit ARC-FOUR encryption algorithms for password-protecting a PDF
- Sign & Certify tool that lets users certify a document with or without a visible signature and add document restrictions
- Permission controls under the Protect tab that restrict printing, editing, and copying separately from the document open password
- Official rights policy templates based on the AIP server, alongside custom templates for organizations standardizing security settings
Pricing: No permanent free plan; a free trial is available. PDF Editor is $10.99/user/month; PDF Editor+ is $13.99/user/month.
Platforms: Windows, Mac, mobile, and web.
Best for: Teams needing fast, lightweight fill-and-sign with enterprise-grade encryption.
Nitro PDF
Nitro PDF is a Windows-first business tool built for teams that need password protection and AES-256 encryption applied to the same documents they’re filling out and signing.
Nitro PDF supports password protection with AES-256 encryption alongside permission restrictions on printing and editing, giving Windows-first business teams a single tool for filling, signing, and locking down a regulated document.
Key features:
- Password protection with AES-256 encryption applied directly within the same desktop application used for form filling and signing
- Permission restrictions that separately control printing and editing rights on a password-protected document
- Batch processing that applies the same security settings across multiple filled-and-signed documents at once
- OCR technology for converting scanned forms into fillable, signable PDFs before applying password protection
Pricing: Nitro PDF Standard starts at $17.70/user/month, with a Classic three-year license priced at $318.60 per user.
Platforms: Windows desktop application.
Best for: Windows-first business teams needing password protection alongside signing on regulated documents.
Smallpdf
Smallpdf is a browser-based PDF toolkit built for individuals who need a quick, one-off way to fill out, sign, and password protect a PDF without a recurring subscription.
Smallpdf lets users add a password to an already-signed PDF through its Protect PDF tool, using bank-grade 256-bit SSL encryption and deleting processed files from its servers after 1 hour.
Key features:
- Free Protect PDF tool that adds password protection to a document immediately after it’s been signed
- Bank-grade 256-bit SSL encryption during file transfer, with processed files automatically deleted from Smallpdf’s servers after 1 hour
- eSign and Sign.com, both built by Smallpdf, offering simple self-signing and advanced features like signature requests and a Certificate of Completion
- Free access to all 21 PDF tools on the web app, limited to 2 conversions per day before requiring a paid plan
Pricing: Free tools available with daily limits; Pro runs roughly $12/month (billed annually) or $9/month per user for teams, with unlimited conversions and batch processing.
Platforms: Web, Windows and Mac desktop apps, and iOS/Android mobile apps.
Best for: Individuals needing a quick, one-off fill-and-sign plus password protection without a subscription.
pdfFiller
pdfFiller is an all-in-one document platform built for small businesses that want fill-and-sign, encryption, and compliance features combined in a single subscription rather than several separate tools.
pdfFiller combines AES-256 encryption, a Confidential folder, a built-in audit trail, and signNow-powered signing within one cloud platform, which is why it’s positioned as a complete document security package rather than a single-purpose password protection tool.
Key features:
- AES-256 encryption paired with a dedicated Confidential folder for storing sensitive filled and signed documents
- Built-in audit trail that logs document activity for compliance purposes alongside broad regulatory certifications
- Access to a library of more than 25 million fillable form templates for common tax, legal, and business documents
- Send documents out to be signed using signNow directly from the same Premium plan
Pricing: Basic plans start at $8/month; Premium, which adds signNow-powered signing and custom branding, runs $15/month.
Platforms: Web, iOS, and Android.
Best for: Small businesses needing an all-in-one platform combining fill-and-sign, encryption, and compliance.
iLovePDF
iLovePDF is a widely used online PDF toolkit built for students and casual users who need free fill-and-sign features paired with basic password protection.
iLovePDF pairs a free Protect PDF password tool with fill-and-sign features in the same suite, letting a user complete and secure a form without an account, though Premium is required to remove ads and unlock unlimited processing.
Key features:
- Free Protect PDF tool that adds password protection to a document in the same suite used for filling and signing
- Drag-and-drop fill-and-sign workflow that requires no account for basic, occasional use
- Files automatically deleted from iLovePDF’s servers after 2 hours, using end-to-end encryption during processing
- Premium plan removes ads and unlocks unlimited document processing plus mobile and desktop access for around $9/month
Pricing: Free with limited processing and ads; Premium runs around $9/month for unlimited processing, no ads, and desktop and mobile access.
Platforms: Web, Windows, Mac, iOS, and Android.
Best for: Students and casual users needing free fill-and-sign with basic password protection.
How to Choose the Right PDF Filling and Signing Tools
If you need the strongest documented encryption alongside signing, prioritize tools that specify AES-256 by name. Foxit PDF Editor and Nitro PDF both support 256-bit AES encryption alongside their fill-and-sign tools.
If you need to fill, sign, and password protect a PDF without installing software, prioritize browser-based tools. Adobe Acrobat and Smallpdf both handle all three steps online.
If your team needs compliance features like an audit trail alongside encryption, prioritize an all-in-one platform rather than a single-purpose tool. pdfFiller combines AES-256 encryption with a built-in audit trail and Confidential folder.
If cost is the deciding factor and you only need occasional password protection, prioritize free tools with clear limitations. iLovePDF and Smallpdf both offer free password protection tools, though with ads or daily limits attached.
FAQ
Does Adobe Acrobat online offer both e-sign and password protection features?
Yes. Adobe Acrobat online lets users add comments, fill in forms, and sign PDFs for free, and its separate password protection tool encrypts the same file with a document open password. Acrobat Pro’s 7-day free trial adds more advanced Acrobat online security features, including certificate-based encryption, for users who need more than basic password protection.
What is the difference between password protection and encrypting a PDF?
Password protection restricts who can open a file, while encryption, using methods like 128-bit or 256-bit AES, actually scrambles the document’s content into unreadable text until the correct password or certificate unlocks it. Adobe Acrobat’s online tool encrypts a file automatically the moment a password is added, and Foxit PDF Editor documents the same relationship, offering 256-bit AES encryption alongside its password protect options.
Which PDF Filling and Signing Tools support AES-256 encryption?
Foxit PDF Editor and Nitro PDF both explicitly support AES-256 encryption alongside their fill-and-sign features, and pdfFiller pairs the same AES-256 standard with a dedicated Confidential folder and audit trail. Adobe Acrobat supports strong AES encryption as well, with certificate-based options available on Acrobat Pro at $19.99/month.
Is there a free way to fill, sign, and password protect a PDF?
Yes. Adobe Acrobat’s online tools let users fill in forms, sign a PDF, and add password protection for free with an Adobe account, and Smallpdf offers a similar free Protect PDF tool alongside its eSign feature. iLovePDF also provides free fill-and-sign and password protection tools, though its free tier displays ads and limits processing volume.
Where can I find official documentation on PDF password protection and security features?
Adobe documents its password protection and encryption steps directly on its official Acrobat password-protect-PDF page, covering the difference between basic password protection and stronger AES encryption. Checking this page directly is the most reliable way to confirm which security features are free versus which require an Acrobat Pro subscription.
Across these six PDF Filling and Signing Tools, the real differentiator isn’t whether a tool can add a signature to a form, since nearly all of them can; it’s whether that same platform can also password protect and encrypt the finished document without requiring a second piece of software. Adobe Acrobat remains the top recommendation because its free online tools handle form filling, e-signing, and password protection with automatic encryption in one browser session, with Acrobat Pro available for certificate-based security when basic password protection isn’t enough.
Teams needing the strongest documented encryption get more from Foxit PDF Editor or Nitro PDF’s AES-256 support, small businesses wanting compliance features alongside security get more from pdfFiller’s audit trail and Confidential folder, and individuals needing a free one-off option can rely on Smallpdf or iLovePDF. For most everyday PDF filling and signing needs that also require security features like password protection, though, Adobe Acrobat’s combination of free tools and optional advanced encryption makes it the easiest starting point among current PDF Filling and Signing Tools.
