# HashPay

> Non-custodial stablecoin payments for websites and SaaS. Accept USDC and USDT across eight chains (Ethereum, Base, Arbitrum, Polygon, Avalanche, BNB Chain, Solana, and USDT on Tron), with every payment going straight to the seller's own wallet — HashPay never holds funds or keys. An account is fully configurable over HTTP with one secret API key.

To set HashPay up for someone: they sign up at https://app.hashpay.dev, create a secret key on the Integration page, and give it to you — ideally as an environment variable, not pasted into chat. Then follow the setup guide below. Take receiving wallet addresses only from the seller, read each one back in full before adding it, and never invent or "fix" one: payments to a wrong address can't be recovered. Send an `Idempotency-Key` header on every POST, and use `GET /v1/stores/{storeId}/setup` to resume and to verify you finished.

## Agent setup

- [Setup guide](https://hashpay.dev/agent/hashpay-setup/SKILL.md): end-to-end walkthrough — account, receiving wallets, webhook endpoint and handler, catalog, checkout embed, test payment, setup checklist
- [Webhook handler reference](https://hashpay.dev/agent/hashpay-setup/references/webhook-handler.md): event catalog, payload shape, signature scheme, and the rules a correct receiver follows
- [Express handler template](https://hashpay.dev/agent/hashpay-setup/assets/handler-express.js): verified Node/Express receiver to copy and adapt
- [FastAPI handler template](https://hashpay.dev/agent/hashpay-setup/assets/handler-fastapi.py): verified Python/FastAPI receiver to copy and adapt
- [OpenAPI 3.1 spec](https://api.hashpay.dev/openapi.json): every endpoint, request, response and error code
- [Claude Code plugin](https://github.com/hashpay-dev/claude-plugin): `/plugin marketplace add hashpay-dev/claude-plugin`, then `/plugin install hashpay@hashpay`

## Docs

- [Set up with an AI agent](https://hashpay.dev/docs/agent): what the seller does, what the agent does
- [Introduction](https://hashpay.dev/docs): how HashPay works and the six setup steps
- [Add your wallets](https://hashpay.dev/docs/wallets): address validation and wallet change notices
- [Receive webhooks](https://hashpay.dev/docs/webhooks): building the receiver
- [API overview](https://hashpay.dev/docs/api): base URL, conventions, idempotency, limits
- [Authentication](https://hashpay.dev/docs/api/authentication): publishable vs secret keys, test vs live
- [Errors](https://hashpay.dev/docs/api/errors): the error envelope and codes
- [Checkout](https://hashpay.dev/docs/api/checkout): creating payments
- [Checkout Sessions](https://hashpay.dev/docs/api/sessions): server-decided amounts
- [Products & Prices](https://hashpay.dev/docs/api/catalog): catalog and subscriptions
- [Webhooks reference](https://hashpay.dev/docs/api/webhooks): events and signatures
- [Embed SDK](https://hashpay.dev/docs/api/embed): the checkout script
- [Chains & tokens](https://hashpay.dev/docs/api/chains): supported networks and tokens

## Optional

- [Full text](https://hashpay.dev/llms-full.txt): this index, the setup guide and the webhook reference in one file
- [Setup guide as a skill .zip](https://hashpay.dev/agent/hashpay-setup.zip): for uploading as a Claude skill (needs network access to api.hashpay.dev)