Running send21 as a service, Invoicing Payments

send21 Agency Implementation, Crypto Payment Workflows for AI Agents

Learn how to build crypto payment infrastructure for your clients using send21's non-custodial API and draft-only keys. This course covers accepting stablecoin payments across Bitcoin, Ethereum, and Solana, automating payment workflows with AI agents via MCP servers, and delivering recurring billing without holding client funds.

Open the decision record for send21

What does running send21 for clients commit you to?

Published figures for this service. Blank fields are not published.

Monthly tool cost
Vendor cost: 0.49% per payment (usage-based, no subscription or setup costs published). Agency must supply technical labor hours for integration and client onboarding.
Time to first value
Not published
Payback
Not modeled, client price, labor, usage, overhead, and expected volume are not supplied
Guided implementation
8 hours

Is send21 worth running as a client service?

send21 provides non-custodial crypto payment infrastructure with scoped API keys and signed webhooks suitable for technical agencies serving crypto-native clients. Agency pricing, labor economics, and client acquisition pacing remain unknown and must be established through the implementation stages.

An agency-fit judgement for reselling this service. It is separate from the tool description on the decision record.

Before you start

What has to be in place before the first client engagement.

Tools and subscriptions

  • send21 free account (no subscription, per-payment fee starting at 0.49%)
  • Client receiver wallet addresses for supported networks (Bitcoin, Ethereum, Solana, stablecoins)
  • Webhook endpoint URLs for client systems to receive signed payment confirmations
  • Shopify or Muse Code integration access if applicable to client stack

People and inputs

  • Technical staff to integrate REST API and manage scoped API keys
  • Process for generating and tracking payment drafts in batches of 25
  • Wallet security and key management guidance for clients
  • Monitoring setup for signed webhooks and payment status updates

Included with the course

7 working documents for delivering this service.

  • send21 Payment Link Setup Checklistchecklist
  • AI Agent Draft API Key Configuration Templatetemplate
  • Webhook Confirmation Verification SOPsop
  • Multi-Chain Payment Pricing Worksheetworksheet
  • Recurring Payment Automation Guideguide
  • Client Onboarding Wallet Address Verification Formtemplate
  • send21 Shopify Integration Deployment Checklistchecklist

Listed by name. These documents are not yet published as individual downloads.