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Last updated: 2026-09-28

Learn: Agentic payments, explained

Plain-language definitions and evidence-based guides to the protocols, wallets, and controls behind AI agents that can pay — x402, AP2, ACP, Visa TAP, Mastercard Agent Pay, MCP payments, and more.

Glossary

Definitions of the core terms in agentic payments.

Glossary

What Is Agentic Payments? Definition, Protocols, and How It Works

Agentic payments let AI agents initiate and execute transactions on a human's behalf. Definitions, protocols (x402, AP2, ACP), and open questions.

Glossary

What Is x402? The HTTP 402 Payment Protocol Explained

x402 is Coinbase's open protocol that uses the HTTP 402 status code to let servers charge AI agents and apps in stablecoins. Origins, mechanics, governance.

Glossary

What Is AP2 (Agent Payments Protocol)? Google's Agentic Payment Standard

AP2 is Google's open protocol for AI agents to make purchases using signed 'mandates.' Origins, mechanism, governance, and how it differs from x402/ACP.

Glossary

What Is the Agentic Commerce Protocol (ACP)? OpenAI + Stripe's Checkout Standard

ACP is OpenAI and Stripe's open standard letting AI agents complete purchases inside a chat interface. Origins, checkout flow, license, and comparisons.

Glossary

What Is an AI Agent Wallet? Definition and How It Works

An AI agent wallet is a crypto or payment wallet built for autonomous AI agents rather than humans, with spend limits and delegated signing. Examples inside.

Glossary

What Are AI Agent Spending Controls? Caps, Approvals, and Mandates Explained

AI agent spending controls are the rules — caps, allowlists, approval thresholds, velocity limits — that bound what an autonomous agent can pay for. How AP2, card networks, and wallets each implement them.

Glossary

What Is Know Your Agent (KYA)? AI Agent Identity Verification Explained

Know Your Agent (KYA) verifies which human or organization an AI agent represents before letting it transact. How Skyfire's KYA works and how it relates to KYC.

Glossary

What Is Mastercard Agent Pay? Agentic Tokens Explained

Mastercard Agent Pay lets AI agents transact using Agentic Tokens — permissioned, tokenized payment credentials. Announcement, mechanism, and named partners.

Glossary

What Is the Visa Trusted Agent Protocol? Definition and How It Works

Visa Trusted Agent Protocol lets merchants cryptographically verify legitimate AI shopping agents instead of treating them as bots. Mechanism, partners, and specs.

Glossary

What Are Payments Over MCP? How AI Agents Pay Through the Model Context Protocol

MCP payments let an AI agent call payment tools (create an invoice, charge a card, issue a refund) through the Model Context Protocol. Official servers, risks, and safeguards.

Guides

Longer, comparative pieces for developers and technical decision-makers.

Guide

Payment MCP Servers Compared (2026): Which Providers Let AI Agents Move Money

16 payment companies checked for an official MCP server that moves money, plus what auth and spending controls each one actually documents.

Guide

Stripe MCP Agent Keys: What Changes on October 31, 2026 and How to Migrate

Stripe MCP stops accepting full-access secret keys and non-Agent restricted keys on Oct 31, 2026. Here's who's affected, how to migrate, and how to scope agent spend.

Guide

x402 vs AP2 vs ACP (and MPP, UCP): Which AI Agent Payment Protocol Should You Use? (2026)

x402, AP2 and ACP solve different layers of AI agent payments: pay-per-request stablecoin settlement, proof of user authorization, and in-chat checkout. Side-by-side comparison, adoption data for 13 providers, and when to use which.

Guide

Agentic Payments Market Map 2026: Who Builds What in AI Agent Payments

A layer-by-layer market map of agentic AI payments in 2026 — protocols, card-network programs, agent wallets, payment MCP servers, and spend-control/policy tools — with 33 companies, primary sources, and status for each.

Guide

AI Agent Spending Policy: A Template for Finance Teams (Caps, Allowlists, Approvals, Audit)

A copy-paste policy template and 9 controls (budgets, allowlists, approval thresholds, credential scoping) for letting AI agents spend under finance oversight.

Guide

Best Payment APIs for AI Agents (2026), by Use Case

There is no single best payment API for AI agents — the right pick depends on what the agent needs to do. A use-case-by-use-case guide to card checkout, stablecoin micropayments, agent wallets, MCP-based account access, and identity, sourced to each provider's own documentation.

Guide

How to Let an AI Agent Pay for API Usage Safely (x402, Prepaid Credits, Virtual Cards, MCP)

Five documented ways to let an AI agent pay for per-call or metered API usage without handing it an open-ended credential: x402 pay-per-request, provider spend limits, single-use virtual cards, an MCP policy layer, and human approval — compared, with a setup checklist.

Guide

Spending controls for AI agents: why agentic payments need a policy layer

Guide

How AI agents make payments through MCP