FAQ
Common questions about Spawnpay. Direct answers, no marketing.
The basics
What is Spawnpay?
Spawnpay is a per-call USDC billing primitive for AI agent tools. Three products share one wallet: a universal BYOK proxy across 25 paid providers ($0.001 per upstream 2xx), a paywall SDK that wraps any async function or MCP tool with a per-call USDC charge, and an MCP server that gives agents wallets, balances, sends, and deposits.
Why does this need to exist?
Card processors floor at $0.30 + 2.9%. ACH settles in days. The math does not close for sub-dollar per-call billing. Agents do not have cards. Cards have chargebacks. None of that fits agent-to-tool transactions. USDC on Base L2 has fractions-of-a-cent fees and sub-second settlement, accessible to a process the same way an API is.
What is the universal proxy?
POST /api/proxy routes any agent call to a registered third-party provider (OpenAI, Anthropic, Groq, Mistral, OpenRouter, Brave, Tavily, Replicate, ElevenLabs, AssemblyAI, Stability, …). $0.001 per upstream 2xx, settled instantly. You bring your own provider key (X-Provider-Key header) — Spawnpay never resells provider tokens.
What is the paywall SDK?
A two-line wrapper around any async function. paywall({ price, vendor }, fn) returns a new function that pre-charges the caller's Spawnpay wallet before executing. Works in Node and Python.
Money, fees, and what you actually pay
How much does it cost?
$0.001 USDC per upstream 2xx through the proxy. 0.5% platform fee on agent-to-agent sends. Free credit of $7 on every new wallet. No subscription, no monthly minimums, no card.
Do you accept credit cards?
No. The whole point of Spawnpay's primitive is that it works for agents — agents do not have cards. Top up your wallet with USDC on Base L2 from any wallet (Coinbase, MetaMask, Rabby, Phantom).
What if my upstream call fails?
Non-2xx responses are free. You only pay the routing fee on successful upstream calls. The upstream itself bills you directly via your BYOK key — Spawnpay never sees your provider invoice.
Are there chargebacks?
No. USDC settles on Base L2 — there is no reversal window. This is one of the reasons the unit economics close at $0.001/call where card networks make it impossible.
Do you take custody of my funds?
Your wallet is custodial — the master seed lives on Spawnpay's VPS, your spk_ key is the access credential. Internal ledger settles sub-cent calls. Deposits and withdrawals are on-chain Base L2 transactions. Treasury at 0xef1a…0161 is public.
How do I withdraw?
POST /api/wallet/send with the destination address and amount. Free above $1, sub-cent gas on smaller amounts (paid by the caller, not Spawnpay).
What about taxes?
Spawnpay does not file or collect tax. If you operate as a vendor (receive payments via the paywall SDK), you are responsible for reporting USDC income to your jurisdiction. The treasury and on-chain receipts make accounting straightforward.
BYOK proxy specifics
What does BYOK mean here?
Bring Your Own Key. For paid providers, you supply your own OpenAI / Anthropic / etc API key in the X-Provider-Key header. Spawnpay forwards your key 1:1 to the upstream. We charge our $0.001 routing fee in USDC. Your upstream provider bills you on their normal cadence.
Are there free providers?
Yes — Wikipedia, HN Algolia, Open-Meteo, Frankfurter FX rates, FxTwitter. All edge-served from the gateway, no key required, no charge. Try them at /playground.
Can I call providers not in your catalog?
Not yet through /api/proxy — the catalog is a fixed allowlist. You can wrap any external call in the paywall SDK yourself, which has no allowlist. Send a PR if there's a provider you want catalogued.
Does Spawnpay store my prompts?
No. The gateway logs the upstream URL, method, response size, and tx hash. We do not retain the request body or the upstream response body. For full prompt/response logging, layer an observability tool (Langfuse, Helicone) on top.
Building on Spawnpay
How do I monetize my MCP server?
Wrap your tool handler with the paywall SDK. Set a price + vendor code. Publish to npm with keyword spawnpay-paywall and a description in the format $<price> USDC per <unit> via spawnpay-paywall. Your MCP auto-appears on /tools. Step-by-step: /guides/monetize-your-mcp.
What's the take rate?
0.5% on per-call settlements via the paywall SDK. You keep 99.5%.
How do per-agent budgets work?
paywall({ price, vendor, budget: { daily, perCall, warnAt } }, fn) enforces caps BEFORE the upstream call. State lives in ~/.spawnpay/budget-state.json with a 24h rolling window. Pre-charge enforcement means an agent in a loop runs out of money before it runs out of API access. Details: /blog/how-agent-budget-enforcement-works.
Can I use the proxy from a serverless function?
Yes. The gateway endpoint is HTTP. Free providers are edge-served (no cold start). Paid providers go through the VPS backend (typical P50 ~200-500ms depending on upstream).
Operations
Is there an SLA?
No formal SLA on the free tier. Gateway is on Vercel's standard production stack. The VPS backend (for paid proxy + tool calls) is monitored. Status updates land at the bottom of /stats.
Where is data stored?
SQLite on the VPS (US-region). Redis for caching. Custodial wallets backed by an HD seed on the VPS. No third-party tracking pixels on the gateway.
Is the source code open?
The paywall SDK (Node + Python), the MCP server, and the example paid MCPs are MIT-licensed at github.com/Robocular/spawnpay. The gateway and backend are closed-source.
Do you need KYC?
No KYC for normal usage (signup, top up, send, withdraw). If you operate as a high-volume vendor receiving payouts, applicable tax / reporting obligations are on you.