Help with Cella PDF.
Start with the guide, check the common questions, or send us a message. We answer every message.
When you report a problem
These four things let us help quickly:
- Your Cella PDF version, from About Cella PDF
- Your computer and its system version
- What you did, and what happened instead
- The PDF, if you're able to share it
Licenses
Moving to a new computer
On the old computer, open Cella PDF License and choose Deactivate This Device. Then enter your key on the new one.
Lost your key?
Your key was emailed when you bought. If you can't find it, send us a message from the address you bought with.
Common questions
How does the free trial work?
The 14-day trial starts the first time you open Cella PDF. Everything works. No sign-up, no card.
What happens when the trial ends?
Cella PDF becomes a free viewer: open, search and print drawings and read every markup. Marking up and measuring need a license key.
Who needs a license?
Anyone who marks up or measures. Everyone else on the project can open, search and print drawings and read every markup free.
How do I move my license to a new computer?
On the old computer, open Cella PDF License and choose Deactivate This Device. Then enter your key on the new one.
Does it need an internet connection?
Only to activate your key and re-check it now and then. Cella PDF keeps working offline for up to 30 days.
Are my drawings uploaded anywhere?
No. There's no account and no cloud. Your drawings stay on your computer and your network.
Does Cella PDF work with AI assistants?
Yes. Turn it on in Settings, under AI Assistants, and an assistant app such as Claude Desktop, Claude Code, VS Code or Cursor can read your open drawings, markups, quantities and sheet text. It's off until you turn it on, and it's included with Cella PDF.
Can an AI assistant change my drawings?
Only if you choose Read and propose changes, and only by asking. Each change shows up with Allow and Deny, nothing happens until you click Allow, and an allowed change is one step of Undo.
What are the system requirements?
Mac: macOS 12 Monterey or later, Apple silicon or Intel. Windows: Windows 10 or 11, 64-bit. Linux: Ubuntu 24.04 or later, or Arch Linux (including Omarchy).
Does anything leave my computer when I use an AI assistant?
Cella PDF itself sends nothing. The assistant is a separate app you choose, and what it reads from your drawings it may send to its own service under that service's terms. Window, then AI Assistant Activity, lists every request.
Do I need the server?
No. The server is optional, for teams who want markups shared live.