Clients and their projects
A client is whoever you're building for — a person or a business. Create them once with their contact details (and, if your bookkeeping uses one, their client number), then link them to their projects. Everyone who works the project sees who it's for, without digging through messages.
Billing details stay locked down
Invoicing details — legal name, tax ID, billing address, fiscal defaults — live in a separate billing profile that only organization admins can see. A teammate who can see which client a project belongs to still can't see that client's tax information.
Nothing about clients is public
If you publish a project to your public portfolio, your client stays out of it: no client names, no financials, nothing. What's public is your work, never your customer list.
Tip
Done working with a client? Archive them — they vanish from pickers but keep their history, and you can bring them back anytime. Accidentally created a duplicate? Merge the two and nothing is lost.