Question 1

How do AI agents make payments?

Accepted Answer

Sponge gives each AI agent its own wallet. Agents can hold funds, make payments, and receive money — just like a human would with a bank account. Your agent connects to Sponge via API or MCP and can transact autonomously within the limits you set.

Question 2

What is x402?

Accepted Answer

x402 is an open payment protocol created by Coinbase that uses HTTP's 402 status code. When an agent calls a paid API, the server responds with a 402 and the price. The agent signs a payment authorization with its wallet, retries the request, and gets the resource. It supports USDC and other stablecoins across EVM chains and Solana.

Question 3

What is MPP?

Accepted Answer

MPP (Machine Payments Protocol) is an open protocol co-authored by Stripe and Tempo for machine-to-machine payments. It uses the 402 status code with standard HTTP authentication headers. MPP supports multiple payment rails including stablecoins, credit cards via Stripe, and Lightning, plus session-based micropayments for high-frequency API calls.

Question 4

How do merchants sell to AI agents?

Accepted Answer

Sponge Gateway sits in front of your API and makes each route payable via x402 or MPP. Point it at your upstream, set a price per endpoint, and share the gateway URL. No SDK integration or upstream code changes required. The gateway handles upstream auth and supports fixed per-request pricing, dynamic rules, or session-based billing. You can also set price to zero for free-but-authenticated routes, giving you wallet-based identity and per-agent access control without charging.

Question 5

Which blockchains does Sponge support?

Accepted Answer

Sponge supports Solana, Ethereum, Base, Arbitrum, Polygon, Tempo, Hyperliquid, and Monad. Agents can hold USDC across chains, swap tokens, bridge between networks, and settle payments on whichever chain your application uses.

Question 6

Is there a spending limit on agent wallets?

Accepted Answer

Yes — you set the controls. Sponge lets you configure per-transaction limits, daily budgets, and approved merchant lists. Your agent operates autonomously within the guardrails you define.

Question 7

How do I get started with Sponge?

Accepted Answer

Sign up at paysponge.com and create your first agent wallet in minutes. Sponge provides SDKs, API docs, and an MCP server so your agent can start transacting immediately.

Turn any API into a paid endpoint.

Three steps to monetize your API

Point

Price

Publish

Everything you need to sell to agents

x402 & MPP

Dynamic Pricing

Zero Code Changes

OpenAPI Import

Session Billing

Agent-Ready via MCP

FAQ

Start selling to agents today