PAP vs UCP: Personal Agent Protocol vs Google’s UCP
UCP is a commerce protocol. PAP is a sign-in protocol that happens to get used for commerce. Shopify sits in both camps, which tells you the people involved don’t see them as either-or.
| PAP | UCP | |
|---|---|---|
| Question it answers | Who is this agent and what may it do on the account? | How does an agent find, buy and return a product? |
| Created by | Sierra and Meta | Google, with Shopify and others |
| Spec status | Not published | Published, Apache 2.0 |
| Payments | Future extension | Yes, via AP2 |
| Industries | Any (retail, travel, mortgages, support) | Commerce |
| First public | Oct 6, 2026 | Jan 11, 2026 |
What each one does
Google announced UCP on January 11, 2026, at the National Retail Federation show. It describes the building blocks of agent shopping: finding products, checking out and what happens after. It plugs into AP2 for payments and supports A2A and MCP.
PAP’s announced scope is smaller and broader at once. Smaller, because it doesn’t touch carts or checkout. Broader, because the examples run from flights and insurance to mortgages and warranty claims. What it standardises is the visit itself: who’s asking, and with what permission.
Where they meet
Both talk about discovery, so a business could end up describing itself twice. Payments are the other seam. UCP has checkout today; PAP lists payment extensions as a possible later step.
The overlap in backers is real. Shopify helped build UCP and is a PAP launch partner. BERI’s comparison also places Walmart in both.
Quick answers
Is PAP a competitor to UCP?
Not directly. UCP standardises the shopping flow; PAP standardises the agent’s sign-in and permissions. Shopify supports both.
Does PAP handle checkout?
Not in the announced first version. Payment extensions are listed as a possible later step.
Is Google part of PAP?
No. Google isn’t named as a partner.
Other comparisons
- All agent protocols in one table
- PAP vs MCP (Model Context Protocol)
- PAP vs A2A (Agent2Agent)
- PAP vs ACP (Agentic Commerce Protocol)
- PAP vs TAP (Trusted Agent Protocol)
- PAP vs PACT (Personal Agent Consent & Trust Protocol)
Sources
- Introducing Personal Agent Protocol · Sierra (Bret Taylor, Clay Bavor), Oct 6, 2026 · primary source
- Under the Hood: Universal Commerce Protocol (UCP) · Google Developers Blog · primary source
- Universal Commerce Protocol · ucp.dev · primary source
- Meta's Personal Agent Protocol Signs Walmart Before It Has a Spec · BERI
pap.md is independent and not affiliated with Sierra, Meta or any PAP partner. Facts here come from the sources listed on each page.