A2A vs x402
They are not competitors — they are different layers of the same stack. A2A lets agents find and talk to each other. x402 lets one agent pay another. Here's the honest breakdown.
The short answer
A2A (Google\u2019s Agent2Agent protocol) is about discovery and messaging between agents — it doesn\u2019t move money. x402 (Coinbase) is the payment rail that settles USDC over HTTP. In a real agent-to-agent payment system you typically use both: A2A to coordinate, x402 to settle.
Side-by-side
When to use which
Use A2A
Agents need to discover each other, delegate tasks, and exchange structured messages across vendors.
Use x402
One agent (or app) needs to pay another per request, in USDC, with no human checkout. See the SDKs.
Use both
Full agent-to-agent payments: A2A to coordinate the task, x402 to settle the price.
Frequently asked questions
Is A2A the same as x402?
No. They operate at different layers and are complementary, not competing. Google’s A2A (Agent2Agent) Protocol lets agents discover one another and exchange tasks/messages; it does not move money. x402 is a payment standard: it defines how a server asks to be paid (HTTP 402) and how the payment settles (USDC over HTTP). A multi-agent system often uses A2A to coordinate and x402 to settle.
Do I need both A2A and x402?
Only if your agents both coordinate and transact. If agents simply call paid endpoints, x402 alone is enough. If you also need structured agent discovery and task delegation, A2A adds that layer on top — and x402 handles the payment when a task has a price.
Does A2A include payments?
Not natively. A2A focuses on agent interoperability — capability discovery, task lifecycle, messaging. Payment is left to a settlement layer, which in practice is usually x402 (or AP2 for the authorization/mandate side).
How do A2A, x402 and AP2 fit together?
Think of it as a stack: A2A for how agents find and talk to each other, AP2 for the authorization/mandate that a payment is allowed, and x402 for actually settling the payment over HTTP. See our protocol comparison and AP2 page for the full picture.
Which should I learn first?
If your goal is to charge for an API or let an agent pay for one, start with x402 — it is the concrete payment mechanism. Add A2A when you need agents to discover and delegate work to each other.
See also: A2A payments explained · full protocol comparison · x402 vs AP2 · AP2