Sponge
What is Sponge?
Sponge is a payments and monetization platform for developers and agent builders that lets agents hold funds, pay for API access, and publish paid endpoints without changing upstream code. It combines Wallet, Gateway, Agent Skill, TypeScript SDK, and OpenAPI Import, with support across Base, Solana, and Tempo. Spending Controls add budgets and limits, and the product is backed by Y Combinator.
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At a glance
- Sponge is best for developers who want agents to pay for API access and manage funds programmatically.
- Yes — The page advertises an MCP server for creating services, adding endpoints, and setting pricing programmatically.
What does Sponge do?
Sponge routes money and payments for agents through two connected products: Wallet for holding and moving funds, and Gateway for turning an API into a paid endpoint. The wallet side lets agents pay, invest, and earn using credit cards, bank accounts, and crypto, while the gateway side sits in front of an existing API and handles per-request monetization through x402 or MPP. Developers can connect an API, set pricing, and publish endpoints without changing upstream code. At scale, Sponge is built for agent workflows rather than manual checkout flows: it supports TypeScript SDK and MCP-based automation, plus OpenAPI import for bulk endpoint setup. The site shows support across Base, Solana, and Tempo, and the wallet experience includes spending controls such as daily budgets, per-transaction limits, and approved domains. Sponge is backed by Y Combinator, and the product examples show agent payments, transfers, and controlled spending in one system.
Why use Sponge?
- It lets you monetize an existing API without upstream code changes, middleware, or a new SDK layer.
- It supports both x402 and MPP, so buyers can accept agent payments through more than one protocol.
- OpenAPI import and MCP automation reduce setup work when you need to publish many endpoints quickly.
- Session billing handles stateful APIs, so you can settle once at the end instead of charging every call separately.
- Wallet spending controls give teams guardrails like budgets, per-transaction limits, and approved domains.
Who is Sponge for?
- API developers who want to monetize endpoints without rewriting their existing service.
- Agent builders who need wallets, payments, and spending controls in one stack.
- Platform teams who want per-request billing with automated settlement.
- Technical founders who want to sell directly to agents with minimal integration work.
What are Sponge's key features?
Wallet
Create and manage agent wallets for payments and balances, with support for Visa, Rain, Base, Solana, and Tempo rails.
Gateway
Route payments through a gateway layer that connects agents to Visa, Rain, Base, Solana, and Tempo, so transactions can be accepted across multiple rails.
Agent Skill
Package payment actions as an agent skill, letting Claude Code and Codex call billing workflows without custom glue code.
TypeScript SDK
Integrate billing logic in TypeScript using the SDK, which helps teams add agent payments without rewriting their existing app structure.
Spending Controls
Set budgets, per-transaction limits, and approved domains, including controls like a $25/day budget, $5/tx limit, and 3 approved domains.
x402 & MPP
Support x402 and MPP payment flows for agent-to-service billing, giving developers standard ways to charge for usage.
Dynamic Pricing
Adjust prices programmatically, including per-request pricing and published rates such as $50.00 or $150, so billing can match usage.
OpenAPI Import
Import OpenAPI definitions to turn existing endpoints into billable services, reducing setup work when publishing APIs.
What does Sponge integrate with?
- Visa
- Rain
- Base
- Solana
- Tempo
- OpenClaw
- Claude Code
- Codex
What are Sponge's use cases?
API monetization for founders
Technical founders use Sponge to sell API access directly to agents without rebuilding their service, using Zero Code Changes to keep the existing stack intact. They can publish pricing fast with OpenAPI Import and Gateway, then let buyers pay per request instead of negotiating custom contracts.
Wallets for agent builders
Agent builders use Sponge to give their agents a Wallet, payments, and Spending Controls in one stack, so autonomous workflows can buy tools without manual approval at every step. Agent-Ready via MCP and Agent Skill help them wire those capabilities into agent workflows with less integration work.
Per-request billing for platforms
Platform teams use Sponge to meter usage at the request level and settle automatically, using Session Billing and x402 & MPP to turn API calls into billable events. Dynamic Pricing helps them adjust charges by endpoint or workload while keeping revenue collection consistent.
Direct sales to agents
API developers use Sponge to expose endpoints that agents can discover and pay for, using Gateway and TypeScript SDK to add monetization without rewriting their existing service. OpenAPI Import speeds up launch, while Spending Controls helps keep agent spend within defined limits.
How does Sponge work?
- Point Sponge at your existing API or service, then use OpenAPI Import or the Gateway to define the first endpoints you want to monetize.
- Price each endpoint with Dynamic Pricing or Session Billing, and set limits with Spending Controls so agent usage stays within your budget rules.
- Publish the service through Agent-Ready via MCP or x402 & MPP so agents can discover it and pay automatically.
- Connect Wallet and supported rails like Visa, Base, or Solana to settle transactions and route funds without manual invoicing.
- Monitor usage, adjust pricing, and expand with the TypeScript SDK or Agent Skill as more endpoints and agent workflows come online.
Frequently asked questions
What is Sponge?
Sponge is a payments and monetization platform for developers and agent builders that lets agents hold funds, pay for API access, and publish paid endpoints without changing upstream code. It combines Wallet, Gateway, Agent Skill, TypeScript SDK, and OpenAPI Import, with support across Base, Solana, and Tempo. Spending Controls add budgets and limits, and the product is backed by Y Combinator.
What is Sponge used for? Who is it for?
Sponge is used for Wallet, Gateway, and Agent Skill. It's built for API developers, Agent builders, and Platform teams.
Does Sponge have an API and what does it integrate with?
The page advertises an MCP server for creating services, adding endpoints, and setting pricing programmatically. It integrates with Visa, Rain, Base, Solana, Tempo, and 3 more.
Editor's read
Check whether your workflow needs both x402 and MPP support, since Sponge exposes both payment flows. Also verify the spending controls you need, such as budgets, per-transaction limits, and approved domains, are enough for your agent policy.
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