toolgrep / Payments & billing / send21
Alternatives to send21
send21: Crypto pay links and API for people and AI agents. 8 products similar to send21, compared on pricing, free tier, API, MCP server, SDK and open source. 6 of 8 have a free tier, 8 of 8 have an API, 8 of 8 offer an MCP server.
- PayAPI Market
x402 marketplace for AI agents
- Pink Agentic AI Payments
Approval layer between AI agents and company money: rules in plain language, per-agent budgets, human approvals, single-use credentials.
- agentsvc.io
Pay-per-call API marketplace for AI agents with 127 services settled in USDC via x402
- Sending
MCP-native messaging orchestration for email, WhatsApp and Telegram
- AurasPay
Non-custodial stablecoin payment gateway for merchants, wallets, AI agents and white-label deployments.
- Signo
AI agents that watch your DeFi positions 24/7, alert you on Telegram, and prepare next steps for you to review and sign.
- Vextorium
Pay-per-call data APIs for AI agents over x402
- 47620
Pay-per-call data API for AI agents with x402 USDC payments over HTTP and MCP
Side by side
| Product | Pricing | Free tier | API | MCP server | SDK | Open source |
|---|---|---|---|---|---|---|
| send21 | Usage-based · from 0.01% | yes | yes | yes | yes | — |
| PayAPI Market | Free | yes | yes | yes | yes | — |
| Pink Agentic AI Payments | Free | yes | yes | yes | no | no |
| agentsvc.io | Usage-based · from $0.002 per call | yes | yes | yes | no | — |
| Sending | Freemium · from €0/mo (free tier: 3,000 emails/mo) | yes | yes | yes | yes | no |
| AurasPay | Usage-based · from 1% per payment received; $0 monthly, no setup or API fee | yes | yes | yes | — | no |
| Signo | Freemium · from $0 | yes | yes | yes | yes | no |
| Vextorium | Usage-based · from $0.001 | no | yes | yes | no | no |
| 47620 | Usage-based · from $0.001 per call | no | yes | yes | no | — |
Facts come from each product's own website, or from its verified owner when they have edited the listing. Each product page shows when it was last verified and how it was extracted. Similarity comes from the products' descriptions.
API
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