Protected viewing
The recipient opens the supported PDF through the protected viewing flow.
Certified Send
Share a PDF with proof of access.
Certified Send combines protected PDF viewing with proof of access. Use it when a sensitive document needs a more deliberate delivery workflow than an ordinary attachment.
No phone number or email required for core Hat use.
The useful difference
A clearer way to handle sensitive work.
Proof of access
The workflow records access evidence so you can review the delivery interaction.
A distinct signing choice
Need a returned signature? Use Signature Request or Verified Digital Signature instead of treating opening as signing.
How it works
Three deliberate steps.
Choose one PDF
Attach a supported PDF in the channel and review its security options.
Enable Certified Send
Choose Certified Send and review the requirements before sending.
Review access evidence
Use the available proof after the recipient completes the access flow.
Know the boundary
Choose controls with clear expectations.
Proof of access does not prove comprehension, agreement or legal acceptance. Protected viewing cannot prevent every external photograph or compromised-device capture. Confirm the evidence fields and legal requirements for your use case.
Review the security evidenceQuestions, answered
Before you get started.
Where can I use Certified Send?
Open City of Hats to review the controls available for your client, content and plan. The app shows applicable requirements before you proceed.
What should I check before sharing sensitive information?
Verify the recipient, use a supported device and choose appropriate access and retention rules. Review the Security Evidence Center for boundaries and evidence status.
City of Hats is free to use. Feature availability and limits vary by plan and client. Premium is optional; review current limits in the app or on the plans page.
Explore what matters next
Build the workflow around your work.
Start with a Hat
Give sensitive work its own space.
Start free. Choose your controls as the work requires them.