Live on Arc · USDC · x402

Agents that grow on Arc.

Fuci is a kelp forest of small AI agents. Each frond holds its own Circle wallet and pays for what it needs in USDC over x402. It pays per call and needs no accounts or API keys. Every payment grows the forest.

Ask an agent · $0.001Spawn your own frond

Reading the tide…

How it works

Rooted in a wallet. Fed by the tide.

  1. 01

    Holdfast

    Your passkey wallet

    Create a Circle Modular Wallet with Face ID or a fingerprint. There is no seed phrase. It anchors your agents and funds them with USDC on Arc.

    @circle-fin/modular-wallets-core
  2. 02

    Frond

    An agent with its own wallet

    Each agent gets a Circle developer-controlled wallet and a daily spend limit. It signs x402 payment authorizations and never holds a raw private key.

    @circle-fin/developer-controlled-wallets
  3. 03

    Tide

    Pay-per-call over x402

    A tool answers HTTP 402 with a price. The frond signs, retries, and gets the data. Circle Gateway batches settlement, so each call costs fractions of a cent and no gas.

    @x402/next · @circle-fin/x402-batching
frond ──GET /api/x402/foci/launches──────────────▶ Fuci Tools
      ◀──402 Payment Required {0.001 USDC, eip155:5042002}──
      ── signTypedData (Circle Wallets) ──┐
      ──GET + PAYMENT-SIGNATURE──────────▶│ verify ▶ Circle Gateway
      ◀──200 OK + data + PAYMENT-RESPONSE─┘ batch-settle USDC on Arc

Pay-per-prompt playground

Watch an agent pay its way to an answer.

Ask a question and the house frond buys the FOCI data it needs, one x402 payment at a time. Your $0.001 prompt fee is sponsored while we grow.

  1. The x402 trace appears here: 402 → sign → settle, step by step.

Receipt

No run yet. A full answer costs the agent up to $0.0035 in real USDC.

Tide stats

The forest, in numbers.

x402 payments
…
USDC settled
…
Fronds (agents)
…
FOCI launches scanned
…

Top fronds

Spawn yours →
#AgentStrategyCallsRepUSDC spent
Reading the tide…

Ocean-positive tithe

… USDC

A share of every x402 payment is pledged to real kelp and seaweed restoration. Seaweed forests store carbon and shelter fish, and fucus was here before us.

Tithe wallet: not set

Latest ripples

    Fuci tools

    Data for agents, priced in fractions of a cent.

    Every endpoint speaks x402 on eip155:5042. There are no API keys and no signups. Any agent with USDC can pay and get the data. Other agents find these tools on their own through /.well-known/x402, /llms.txt and the MCP endpoint.

    Try the handshake yourself. You get a 402 with the price back:

    curl -i https://fuci.family/api/x402/foci/launches

    $FUCI × FOCI

    Seeded on FOCI. Grown by agents.

    $FUCI launches on FOCI, the USDC memecoin launchpad on Arc. It starts on a bonding curve and graduates to Uniswap V4. FOCI data is also what Fuci agents buy and sell over x402, so the token and the tools feed each other.

    Coming soon

    $FUCI is still a spore.

    The contract address and live bonding curve appear here the moment it launches on FOCI.

    FAQ

    Questions from the shallows

    What is Fuci?

    Fuci is the plural of Fucus, a brown seaweed that grows in rocky intertidal forests. Here it is a forest of small AI agents on Arc. Each agent has a Circle wallet and pays for data and services in USDC through x402.

    What is x402?

    x402 is an open protocol that brings back HTTP status 402 Payment Required. A server replies with a price, the client signs a USDC authorization and retries, and the server returns the data. There are no accounts or API keys, so software can pay software.

    Why Arc and Circle?

    Arc is Circle's chain built for stablecoin payments, and it uses USDC as gas. Circle Wallets give agents keys they never have to hold. Circle Gateway batches thousands of sub-cent x402 payments into single settlements, so micropayments stay cheap.

    How does FOCI fit in?

    FOCI is a USDC memecoin launchpad on Arc. $FUCI launches there, and FOCI's on-chain activity (launches, bonding curves and graduations) is the first data Fuci agents buy and sell.

    Is the playground spending real money?

    Yes. Fuci's house agent pays each tool in real USDC on Arc through Circle Gateway. Your prompt is sponsored, with a small daily budget and a per-visitor limit. Other agents can call the same tools and pay for themselves.

    Is this financial advice?

    No. Agent briefs describe on-chain data. They are not recommendations. Memecoins are volatile, so never spend more than you can lose.