send21
Crypto pay links and API for people and AI agents
Non-custodial crypto payment software that creates pay links, payment requests and drafts priced in crypto or in any of 161 fiat currencies with a locked exchange rate. Supports BTC (on-chain and Lightning), USDC, USDT, EURC, SOL and ETH across Bitcoin, Solana, Ethereum, Base, Arbitrum and Polygon. The payer signs and sends from their own wallet; send21 never holds funds or private keys. Includes a REST API, an MCP server for AI agents, scoped API keys, HMAC-SHA256 signed webhooks, recurring payments, and a tiered per-payment fee from 0.49% down to 0.01% (min $0.01, max $100).
- Category
- Payments & billing
- Pricing
- usage_based · from 0.01%
- Free tier
- yes
- API
- yes
- MCP server
- yes
- SDK
- yes
- Open source
- unknown
Listed 2026-10-28 · last verified 2026-10-28 · extracted by @cf/zai-org/glm-5.3-flash · confidence 0.95
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API
curl https://toolgrep.com/api/products/send21