About send21

send21 is non-custodial payment software: it prepares clean, verifiable payment instructions for BTC, USDC, USDT, and EURC — across Bitcoin, Solana, Ethereum, and Base — and watches the chain for confirmation. Funds always move directly from the sender's own wallet to the receiver.

What send21 is

• A draft & pay-link generator: fixed-amount or fiat-pegged payment drafts with a locked, recorded exchange rate in any of 165 world currencies.
• A chain watcher: it matches the payment on-chain and fires HMAC-signed webhooks and emails as it is seen and confirmed.
• An API-first platform: everything a human does in the UI, an AI agent does over REST or the built-in MCP server — with scoped keys that can never move funds.

What send21 is not

send21 is not a custodian, exchange, broker, money transmitter, or payment service provider. It never holds, transmits, converts, or has access to funds or private keys, contains no signing code, and never broadcasts transactions. Signing and broadcasting always happen in the sender's own wallet — a full server compromise could not move a single satoshi. This is non-custodial by structure, not by promise; the details are in our terms of service.

How it makes money

A single transparent fee per payment, tiered by size — from 0.49% on the smallest payments down to 0.01% above $100,000, capped at $100. On multi-output drafts the fee is a visible output in the transaction you sign; on single-output payments it accrues to the creator's account. No subscriptions, no spread on exchange rates. Full details on the pricing page.

Privacy by default

No KYC, no tracking, no analytics, no ad pixels. The platform stores an email address (encrypted) and little else — see the privacy policy for exactly what is kept and for how long.

Contact

• General: [email protected]
• Account or payment issues: [email protected]
• API & integrations: [email protected]
• Privacy & GDPR requests: [email protected]

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