# Spawnpay

> One key. Every paid tool. Universal payment proxy for AI agents — route any paid API (OpenAI, Anthropic, OpenRouter, Brave, Tavily, Replicate, …) under a single Spawnpay key, billed in USDC on Base L2 with unified receipts and cross-provider budgets. BYOK upstream, $0.001 flat routing fee.

Spawnpay is two products that share one wallet:

1. **Universal proxy** — `POST /api/proxy` routes any agent call to a registered third-party provider, charges a $0.001 USDC routing fee per upstream 2xx, returns the full upstream response plus a tx-hash receipt. BYOK only — no quota reselling, no TOS risk.
2. **Paywall SDK** — `paywall({ price, vendor }, fn)` wraps any async function with a per-call USDC charge so MCP authors can monetise their tools without Stripe.

Agents get a free $5 USDC signup credit, on-chain wallet on Base L2, and unified cross-provider budget guardrails out of the box.

## Core docs

- [Homepage and product overview](https://spawnpay.ai): What Spawnpay does, example code in Node and Python, install paths, live demo
- [OpenAPI 3.1 spec](https://spawnpay.ai/openapi.json): Full machine-readable API spec covering /api/proxy, /api/signup, /api/wallet/*, /api/stats. Import into Postman, Swagger UI, or your agent's tool generator.
- [Interactive Playground](https://spawnpay.ai/playground): Browser-based proxy tester — pick provider, paste path, hit run. Free providers (Wikipedia, HN, Open-Meteo, Frankfurter, FxTwitter) work edge-served with zero setup.
- [Guide: Monetize your MCP in 5 minutes](https://spawnpay.ai/guides/monetize-your-mcp): Step-by-step tutorial for MCP tool authors using the paywall SDK.
- [Spawnpay vs OpenRouter comparison](https://spawnpay.ai/vs/openrouter): When to pick each one + how to use them together.
- [Top up your wallet (deposit guide)](https://spawnpay.ai/deposit): How to send USDC on Base L2 to a Spawnpay agent wallet — 15-second settlement, no card, no signup wall.
- [Use cases (34 patterns)](https://spawnpay.ai/use-cases): Long-form guides for agent billing, MCP monetization, BYOK proxying, per-call USDC charging.
- [Blog — essays on agent billing](https://spawnpay.ai/blog): Spawnpay vs Stripe, why USDC on Base, the MCP monetization gap, how agent budgets work, the pay-as-you-go API economy.
- [Free LLM cost calculator](https://spawnpay.ai/llm-cost-calculator): Interactive monthly LLM spend estimator across OpenAI/Anthropic/Groq/Mistral/DeepSeek/Together, with Spawnpay flat-fee vs Stripe baseline comparison.
- [Pricing](https://spawnpay.ai/pricing): Per-call pricing detail, free credit, agent-to-agent send fee, deposit/withdrawal terms, paywall SDK take rate.
- [FAQ](https://spawnpay.ai/faq): Every common question with FAQPage JSON-LD answers — what is Spawnpay, do you accept cards, BYOK, budgets, custody.
- [Security & custody](https://spawnpay.ai/security): Concrete custody model, ledger locks, idempotency, panic mode, data retention.
- [About](https://spawnpay.ai/about): Why Spawnpay exists, what is shipped, what it is not.
- [Spawnpay vs Helicone](https://spawnpay.ai/vs/helicone), [vs Portkey](https://spawnpay.ai/vs/portkey), [vs Langfuse](https://spawnpay.ai/vs/langfuse), [vs Vellum](https://spawnpay.ai/vs/vellum), [vs AWS Bedrock](https://spawnpay.ai/vs/aws-bedrock), [vs Azure OpenAI](https://spawnpay.ai/vs/azure-openai), [vs Vertex AI](https://spawnpay.ai/vs/vertex-ai): When to pick each one + how to use them together.
- [One-line install](https://spawnpay.ai/install-page): curl -fsSL https://spawnpay.ai/install | bash — auto-detects Claude Desktop / Cursor / Cline configs.
- [Agent templates](https://spawnpay.ai/templates): Pre-built MCP server bundles for research, writing, coding, monitoring, and trading flows.
- [Ledger data](https://spawnpay.ai/stats): Available ledger totals may include promotional activity. Customer revenue is unverified.
- [Publish your paid MCP](https://spawnpay.ai/contribute): 5-min step-by-step for MCP authors: wrap, name, publish, auto-list.
- [Universal proxy](https://spawnpay.ai/#proxy): How `/api/proxy` works, BYOK model, $0.001 USDC routing fee
- [Providers catalogue](https://spawnpay.ai/providers): All 33 registered upstream providers (20 BYOK paid + 13 free edge-served), one page each, curl + Node examples
- [Paywall SDK (Node)](https://spawnpay.ai/docs#paywall): `spawnpay-paywall` npm package, two-line wrap of any async function with a USDC price; also exposes `proxy()` helper
- [Paywall SDK (Python)](https://spawnpay.ai/docs#paywall): `spawnpay-paywall` for Python, mirrors the Node API with `@paywall` decorator plus `proxy_async` / `proxy_sync`
- [MCP server](https://spawnpay.ai/docs): `spawnpay-mcp` — wallet, signup, balance, send, deposits, referral tools for any MCP-aware agent
- [Live stats](https://spawnpay.ai/stats): Real on-chain numbers (agents, transactions, USDC volume, treasury)

## Universal proxy providers

- [OpenAI via Spawnpay](https://spawnpay.ai/providers/openai): GPT-4o, GPT-4o-mini, DALL-E behind one spk_ key
- [Anthropic via Spawnpay](https://spawnpay.ai/providers/anthropic): Claude Opus, Sonnet, Haiku — unified billing receipts
- [OpenRouter via Spawnpay](https://spawnpay.ai/providers/openrouter): 200+ models with cross-model budgets
- [Brave Search via Spawnpay](https://spawnpay.ai/providers/brave): Web search with per-query receipts
- [Tavily Search via Spawnpay](https://spawnpay.ai/providers/tavily): AI-optimised search for RAG agents
- [Serper via Spawnpay](https://spawnpay.ai/providers/serper): Google SERP behind metered USDC billing
- [Replicate via Spawnpay](https://spawnpay.ai/providers/replicate): FLUX, SDXL, Whisper, any Replicate model
- [Mistral via Spawnpay](https://spawnpay.ai/providers/mistral): EU-resident LLMs with unified USDC billing
- [Groq via Spawnpay](https://spawnpay.ai/providers/groq): Fastest LLM inference, USDC receipts
- [Together AI via Spawnpay](https://spawnpay.ai/providers/together): Hosted open-source models
- [Cohere via Spawnpay](https://spawnpay.ai/providers/cohere): Command R+ / Embed / Rerank
- [Voyage via Spawnpay](https://spawnpay.ai/providers/voyage): Best-in-class embeddings
- [ElevenLabs via Spawnpay](https://spawnpay.ai/providers/elevenlabs): TTS with base64 audio response
- [AssemblyAI via Spawnpay](https://spawnpay.ai/providers/assemblyai): Speech-to-text with auto-polling
- [Stability AI via Spawnpay](https://spawnpay.ai/providers/stability): SDXL, Stable Image, Stable Audio
- [DeepSeek via Spawnpay](https://spawnpay.ai/providers/deepseek): V3 + R1 reasoning models
- [Fireworks AI via Spawnpay](https://spawnpay.ai/providers/fireworks): Llama, Qwen, DeepSeek hosted
- [Perplexity via Spawnpay](https://spawnpay.ai/providers/perplexity): Sonar with built-in web search
- [Hyperbolic via Spawnpay](https://spawnpay.ai/providers/hyperbolic): GPU model hosting
- [xAI via Spawnpay](https://spawnpay.ai/providers/xai): Grok models
- [Wikipedia via Spawnpay](https://spawnpay.ai/providers/wikipedia): free, edge-served, no key needed
- [Hacker News via Spawnpay](https://spawnpay.ai/providers/hn): free Algolia search
- [Open-Meteo via Spawnpay](https://spawnpay.ai/providers/openmeteo): free weather forecasts
- [Frankfurter via Spawnpay](https://spawnpay.ai/providers/frankfurter): free ECB FX rates
- [FxTwitter via Spawnpay](https://spawnpay.ai/providers/fxtwitter): free tweet metadata

## MCP directory

- [Full MCP directory](https://spawnpay.ai/tools): 228 MCP servers indexed (28 paid featured first + 200 open-source)
- [Machine-readable marketplace feed](https://spawnpay.ai/marketplace.json): JSON catalog of all paid + free MCPs with install commands, prices, descriptions. Refreshed weekly. AI agents and crawlers should prefer this over scraping the HTML directory.
- [Search MCPs](https://spawnpay.ai/tools/c/search): Web search and information retrieval
- [Scrape & browser MCPs](https://spawnpay.ai/tools/c/scrape): JS-rendering scrapers, hosted Chrome
- [Database MCPs](https://spawnpay.ai/tools/c/database): Postgres, MongoDB, Redis, Supabase, ClickHouse
- [GitHub & Git MCPs](https://spawnpay.ai/tools/c/github): Repo browsing, PRs, issues
- [LLM & AI MCPs](https://spawnpay.ai/tools/c/llm): Model gateways, embeddings, agent frameworks
- [Vision MCPs](https://spawnpay.ai/tools/c/vision): Screenshots, OCR, image generation
- [File & document MCPs](https://spawnpay.ai/tools/c/files): PDF, DOCX, CSV parsing
- [Cloud & infra MCPs](https://spawnpay.ai/tools/c/cloud): AWS, GCP, Azure, Cloudflare, K8s

## Flagship paid MCPs (live, charging USDC)

- [paid-search-mcp](https://spawnpay.ai/tools/paid-search-mcp): Web search at $0.005/call
- [paid-fetch-mcp](https://spawnpay.ai/tools/paid-fetch-mcp): URL fetch with markdown extraction at $0.002/call
- [paid-arxiv-mcp](https://spawnpay.ai/tools/paid-arxiv-mcp): Arxiv search at $0.003/call
- [tweet-fetcher-mcp](https://spawnpay.ai/tools/tweet-fetcher-mcp): Tweet fetch via fxtwitter at $0.001/call

## How to use

Agents can call paid MCPs after signing up for a Spawnpay wallet through the `spawnpay-mcp` server (auto-funds with $7 free credit on first use). Authors wrap any async function with `paywall({ price, vendor }, fn)` to charge USDC per call. Deposits and withdrawals use Base L2; internal transfers use the ledger. Ledger totals do not establish customer revenue.

## Repo

- [GitHub: spawnpay/sdk](https://spawnpay.ai/docs): Monorepo with paywall SDKs, MCP server, gateway, and example paid MCPs