StablePay

Self-custody USDC checkout for developers and AI agents. Take USDC on Base and Solana straight into your own wallet.

What it does

• Self-custody, receive-only. StablePay holds no private keys. Funds go directly to the merchant's own wallet.
• USDC on Base and Solana. One hosted checkout page with both networks.
• No chargebacks. No card processor in the middle that can reverse or freeze payments.
• Base: unique-amount matching. Each checkout gets a slightly different amount (price plus 0.000001 to 0.009999 USDC), so the exact transfer identifies the order.
• Solana: Solana Pay transfer request with a per-checkout reference.
• Signed webhooks (HMAC-SHA256, retried for 24 h) for paid, expired and subscription renewal events.
• Subscriptions: period-based checkouts with an automatic renewal checkout and webhook before access ends.

Create a checkout

curl -X POST https://pay.shipfast.sh/v1/checkouts \
  -H "Authorization: Bearer $STABLEPAY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"amountUsd":"19.00","productName":"Pro monthly",
       "customerRef":"user_123","successUrl":"https://app.example/ok"}'
# 201 {"id":"co_...","url":"https://.../c/co_...","expiresAt":"..."}

Accounts are created by the operator; there is no self-serve signup yet.

For AI agents and tools

• /llms.txt and /llms-full.txt: full API reference as plain text
• /openapi.json: OpenAPI 3.1 spec
• /.well-known/api-catalog: API catalog (RFC 9727)

Terms

StablePay is not available to residents of Vietnam. Requests from blocked countries receive HTTP 451.