The six protocols we track

Paid by Agents is a monthly briefing on how AI agents move money — neutral, sourced, no vendor spin. Every issue keeps score across all six competing standards: what actually shipped versus what was press-released. Here's the field as of July 2026.

AP2 · DONATED TO FIDO

Agent Payments Protocol

The most widely backed open protocol. Cryptographically signed mandates prove an AI agent acted within your authorization — now donated to the FIDO Alliance to become an industry standard.

Open, payment-agnostic spec — cards, bank transfers, crypto via the x402 extension
Intent / Cart / Payment mandates form a non-repudiable audit trail
Built on W3C Verifiable Credentials; extends A2A + MCP
60+ partners: Amex, Mastercard, PayPal, Coinbase, Adyen, Worldpay

Read the full comparison ↗

ACP · LIVE

Agentic Commerce Protocol

Checkout-centric, and already live inside ChatGPT — the largest consumer AI surface on the planet.

Deep ChatGPT integration; Link Agent Wallet caps what each agent may spend
Stripe rails plus streaming / stablecoin micropayments on Tempo
Stripe's Agentic Commerce Suite spans OpenAI, Microsoft, Meta and Google AI Mode

UCP · LIVE IN GOOGLE AI MODE (US)

Universal Commerce Protocol

A full-journey open standard — discovery to checkout to post-purchase — already powering Google AI Mode checkout for eligible US retailers.

Wraps AP2, A2A and MCP; REST / JSON-RPC
Backed by Shopify, Etsy, Wayfair, Target and Walmart
Endorsed by Visa, Amex, Adyen and Stripe; Google Pay / Wallet first

x402 · SHIPPING

HTTP-native payments

Coinbase's protocol revives the reserved HTTP 402 status code for machine-to-machine micropayments — the de-facto web3 agent rail.

Crypto / stablecoin payments directly between agents
Agent wallets for autonomous machine-to-machine spend
The A2A x402 extension aligns it with AP2 mandates

VISA TAP · PILOTS

Trusted Agent Protocol

Agent identity and trust signals over Visa's network, with Intelligent Commerce issuing scoped agent tokens.

Agent-specific tokens with spend limits — not your raw card number
Visa co-chairs the FIDO Payments Working Group
Currently in pilots

MASTERCARD AGENT PAY · LIVE PILOTS EU + IN

Mastercard Agent Pay

Agentic Tokens built on proven tokenization, with a "Know Your Agent" framework — live in pilots across Europe and India.

Card-on-file and passkey tokenization, scoped to each agent
Live pilots: ING and Worldline (EU); Axis, RBL and Razorpay (India)
Extended into UCP

Read the complete guide ↗