AP2: Verifiable Agent Payments

Demonstration of AP2 protocol using x402, showing two agents executing verified payments over A2A on Base Sepolia, with optional card or EIP‑3009 token support.

Gemini Base Sepolia AP2 x402

Overview

A demo of the the AP2 (ap2-protocol.org) facilitating payments between two agents connected and communicating using A2A using the x402 protocol.

Tech stack

Gemini

Google's natively multimodal AI model: understands and operates across text, code, audio, image, and video.

Gemini is Google's most capable and general AI model, engineered from the ground up to be natively multimodal: it seamlessly understands and combines information across text, code, audio, image, and video inputs. The technology is optimized for flexibility, running efficiently on everything from data centers to mobile devices. It is deployed in three key sizes: Ultra (for highly complex tasks), Pro (for broad scaling), and Nano (for efficient on-device tasks). Developers access this power via the Gemini API to build next-generation applications.

https://deepmind.google/technologies/gemini/

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Base

Base is a secure, low-cost Ethereum Layer 2 (L2) network, built on the OP Stack and incubated by Coinbase, designed to scale the blockchain for mass adoption.

Base is Coinbase's flagship L2 solution: an Ethereum-based network built on the open-source OP Stack (Optimism). It delivers full Ethereum Virtual Machine (EVM) compatibility at a fraction of the cost, leveraging Ethereum's mainnet for core security. The primary objective is clear: onboard the next billion users to the cryptoeconomy. Developers gain immediate access to the Coinbase ecosystem, including its 110 million+ verified users and powerful fiat onramps, streamlining the launch and adoption of decentralized applications (dApps).

https://base.org/

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Sepolia

Sepolia is Ethereum's recommended, public Proof-of-Stake (PoS) testnet: the essential staging environment for smart contract and dApp deployment.

Sepolia is the official, primary testnet for Ethereum application developers, replacing the deprecated Goerli network. It operates on a Proof-of-Stake consensus mechanism, closely mimicking the Ethereum mainnet for realistic pre-deployment testing. The network uses a permissioned validator set, ensuring stability for developers. Key technical specifics: its Chain ID is 11155111, and unlike its predecessors, the supply of its native test currency, SepoliaETH, is uncapped, mitigating token scarcity issues. Use Sepolia to rigorously test your decentralized applications and smart contracts before committing to mainnet deployment.

https://sepolia.etherscan.io/

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AP2

AP2 (Agent Payments Protocol) is the open, verifiable standard securing AI-driven commerce transactions with cryptographically signed mandates.

AP2 (Agent Payments Protocol) establishes the secure, open framework for AI agents to transact on a user's behalf. Developed by Google and industry leaders, this non-proprietary protocol extends Agent2Agent (A2A) and Model Context Protocol (MCP) standards. Its core innovation is the use of cryptographically signed mandates: tamper-proof digital contracts that provide verifiable proof of user intent and authorization for every payment. This system ensures clear accountability, prevents ecosystem fragmentation, and supports all payment types, from cards to stablecoins, building essential trust in autonomous commerce.

https://ap2-protocol.org

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x402

x402 is the open payment protocol that activates the dormant HTTP 402 status code, enabling instant, machine-native settlement for digital resources.

This is the internet’s native payment layer: x402 revives the HTTP 402 “Payment Required” status code, transforming the standard request-response cycle into a direct, pay-per-use transaction. The protocol allows a server to respond with a 402 status, detailing payment requirements (e.g., USDC on Base), which an AI agent or client wallet fulfills instantly. This system eliminates traditional friction like accounts and subscriptions, providing permissionless, near-zero-fee settlement, often in under two seconds. It is critical infrastructure for the emerging agentic economy, allowing autonomous AI agents to discover and pay for API access and data without human intervention.

https://www.x402.org/

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