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Circle

Key player

Issues USDC — the default settlement asset for agent payments.

Settlement & Identity Rails x402USDC

What Circle builds for agent payments

Almost every x402 demo in this directory settles in USDC. That is not accidental: agents need a stable unit of account, sub-cent transfers, and regulated rails. Circle’s USDC on Base, Solana and other chains is the default answer.

Circle also invests in “agent stack” narratives — programmable wallets, compliance-friendly stablecoin flows — so developers do not reinvent treasury for every agent.

Open-source projects that build on Circle

11 repositories in this directory name Circle in their title, description or topics — useful if you want working code rather than documentation. The most-starred are below.

  • Inktoll  62★ · TypeScript
    A decentralized micro-settlement protocol enabling autonomous AI agents to pay publishers for premium content via Circle Programmable Wallets and x402 nanopayments.
  • Sluice  33★ · TypeScript
    Sluice is a toll booth for the AI-read web. Creators price the smallest unit of what they make, AI agents pay it automatically in USDC, and Circle Gateway batches the tiny payments and settles them on Arc, gas-free and verifiable.
  • ledgerflow  15★ · Rust
    A chain-agnostic AI-native payment infrastructure, authz layer for x402
  • salesforce-programmable-wallets  13★ · Apex
    Programmable Wallets for Salesforce, powered by Circle Programmable Wallets, is an open source solution built on Circle Programmable Wallet technology to operating 100% within the Salesforce ecosystem.
  • alphachef  12★ · JavaScript
    Autonomous on-chain alpha signal intelligence. AI agent monitors multiple on-chain and social sources 24/7, detects high-probability signals, and publishes them to a live feed. Pay $0.01–$0.05 USDC per signal via Circle x402 nanopayments on Arc.
  • CrawlPay  5★ · TypeScript
    Monetize your site for the AI era. AI bots pay $0.001 USDC per page via Arc Nanopayments.
  • AgenticCommerce  2★ · HTML
    x402 payment protocol implementation in .NET - enable AI agents to pay for your APIs with USDC micropayments
  • eXpress402  1★ · TypeScript
    high speed x402 extension using Yellow
  • arc-pulse  0★ · TypeScript
    "AI-Powered Autonomous Payment Agent reviving HTTP 402. Built with Gemini, Circle, and Arc."
  • agentwallet-crewai-tool  0★ · Python
    Non-custodial wallet tools for CrewAI agents — EVM + Solana, spend limits, x402 payments, CCTP bridge
  • AgentNexus2  0★ · TypeScript
    AgentNexus2 is Base-native infrastructure for agent-to-agent payments, built around small, deterministic USDC escrow and settlement flows. It is designed for developers integrating autonomous agents and services that require verifiable, non-custodial payment coordination. AgentNexus2 is not a consumer application or marketplace.

Circle vs other settlement & identity rails

Company Protocols HQ Founded OSS repos
Circle x402, USDC Boston, USA 2013 0
Skyfire Agent identity USA 2024 0
Alchemy Base, EVM San Francisco, USA 2017 0
Base x402, USDC USA 2023 0
Cloudflare x402 San Francisco, USA 2009 0
Tempo Payments L1/L2 Remote 0

Also supporting x402/USDC: Coinbase, Crossmint, Payman, Base, Cloudflare, Daydreams.

On mpp.best

USDC payments guide →Accept USDC →

Related companies

Skyfire
Agent identity
Alchemy
Base
Base
x402
Cloudflare
x402
Tempo
Payments L1/L2

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