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Carbon Retirement, Built for AI Agents

The first carbon marketplace with a native x402 endpoint: your agent discovers credits, quotes live prices, and retires carbon onchain — returning a public certificate in a single flow.

Read the DocsView the Agent Manifest
https://x402.klimalabs.com/.well-known/x402.jsongithub.com/KlimaDAO/Klima-Protocol-x402-MCP-documentation
  • x402 — Carbonmark leverages x402 for powering agentic carbon transactions.
  • Circle — Carbonmark uses Circle's USDC coin to enable instant transaction settlement.
  • Base — Carbonmark's infrastructure is built atop the Base blockchain.
  • Model Context Protocol — MCP enables agentic interactions with Carbonmark's platform.

What is agentic carbon retirement?

Agentic carbon retirement is the process by which an AI agent autonomously purchases and permanently retires carbon credits on a user’s behalf. On Carbonmark, agents use the x402 payment protocol to discover credits, receive live quotes, execute onchain retirement, and return a publicly verifiable certificate — no human browsing required.

  1. Step 1

    Discover

    Available carbon credits

    GET /discover
  2. Step 2

    Quote

    Live on-chain prices

    GET /quote
  3. Step 3

    Retire

    Credits in a single approved transaction

    GET /prepare/retire
  4. Step 4

    Certificate

    A public Carbonmark certificate as permanent proof

    GET /certificate

Success Stories

Two integration paths

Free GET/POST endpoints; your agent submits the transaction from its own Base wallet

Best for: wallet-connected agents (Base MCP, custom stacks)

Sign one authorization — our executor submits onchain and covers gas

Best for: any agent or wallet, no ETH required

AI Speed. Onchain Proof.

Every agent-executed retirement is recorded on Base and resolves to a public Carbonmark certificate — showing the project, vintage, tonnage, and beneficiary.

Autonomous doesn’t mean unaccountable: anyone can verify what your agent did, forever.

Retirement Certificate

Verified onchain
Project
Harvey Manning Park ExpansionRegen Registry · REGEN-C02004
Vintage
2021
Tonnage
0.090071 tCO₂e
Beneficiary
Automated Carbon Retirement Bot
Retired
August 2026

GET /certificate

View the live certificate

Humans in the loop

Building an agentic integration?

Our Solutions team helps you scope, test in sandbox, and go live.

Talk to Solutions

Key facts

  • Carbonmark lets AI agents and HTTP clients retire carbon credits autonomously in four steps: GET /discover (list retirable credits), GET /quote (live onchain price incl. fees), GET /prepare/retire (single approved transaction), GET /certificate (public onchain proof).
  • Payments use the x402 payment protocol; a machine-readable manifest is published at /.well-known/x402.json for agent discovery.
  • Two integration paths: free GET/POST endpoints where the agent submits from its own Base wallet, or one signed authorization where Carbonmark's executor submits onchain and covers gas (no ETH required).
  • Every agent-executed retirement resolves to a public Carbonmark certificate on Base — verifiable onchain, permanently.
  • MCP integration is available for wallet-connected agent frameworks.

Frequently asked questions

Carbonmark x402 & MCP FAQ

Can AI agents buy carbon credits?

Yes. On Carbonmark, AI agents can autonomously purchase and retire verified carbon credits through our x402 endpoint — a machine-payable API built for agentic transactions. The agent discovers available credits, requests a live quote, executes the retirement onchain, and receives a public Carbonmark certificate as proof, all without a human clicking through a checkout flow. Any agent framework that can make HTTP requests can integrate, and wallet-connected agents can transact directly through our Base MCP integration.

What is Carbonmark's x402 endpoint?

Carbonmark's x402 endpoint is an API that lets AI agents and other HTTP clients retire tokenized carbon credits on the Base blockchain using the x402 payment protocol. It exposes a simple four-step flow — discover, quote, retire, certificate — and publishes a machine-readable manifest at /.well-known/x402.json, so agent crawlers and registries can find and index the service automatically. Discovery and quote calls are free; payment only occurs when a retirement is executed.

Does my AI agent need a crypto wallet or ETH to retire carbon?

No wallet with ETH is required. Carbonmark supports a gasless relay path: the user or agent signs a single EIP-712 authorization for the payment amount, and an executor submits the transaction onchain and covers the gas. This means agents can retire carbon with USDC alone — no Base account setup, no gas management, no bridging. Agents that do control their own funded wallet (for example, via Base MCP) can skip the relay and submit transactions directly.

How do I verify a retirement my AI agent made?

Every retirement — human- or agent-initiated — resolves to a public Carbonmark certificate URL showing the project, vintage, tonnage, retirement date, and named beneficiary. The underlying transaction is recorded on the Base blockchain, so the retirement can be independently verified onchain by anyone, at any time. Additionally, for enabled carbon registries, retirement events occurring onchain are also linked to retirement events in the credit's host registry on a one-to-one basis. Autonomous doesn't mean unaccountable: your agent returns a link, and that link is permanent, public proof.

What does agentic carbon retirement cost?

Calling the API is free — discovery, quotes, and integration carry no charge and no subscription. You pay only when a retirement executes: the quoted price includes the market price of the selected carbon credits plus the x402 fee, with no hidden costs added after the quote. Because quotes reflect live onchain pricing, your agent always knows the exact total before it commits.

Is an agent-initiated carbon retirement reversible?

No. Retirement permanently removes a carbon credit from circulation — the credit is burned onchain and can never be resold or reused, which is precisely what makes it a credible climate claim. That's also why the flow is quote-first: your agent receives the exact price, project, and tonnage before any payment is authorized, so nothing irreversible happens without an explicit, informed approval step. We recommend agents surface the quote to their user (or check it against configured limits, like a maximum price per tonne) before executing.

Which AI frameworks work with Carbonmark?

Any framework that can send HTTP requests can use the x402 endpoint directly. For deeper integrations, Carbonmark supports the Model Context Protocol (MCP) via Base MCP, allowing tools like Claude Code and other MCP-enabled agents to retire carbon from a plain-language instruction — for example, 'Retire 2 tonnes of carbon under $15 per tonne for Acme Corp.' See the integration docs for setup guides.