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Sly is an API platform for moving money with AI agents in the loop. It sits between your application (or your agent) and the payment networks — stablecoin rails, card networks, banking infrastructure — and adds three things those networks don’t give you directly:
  1. Identity for agents. Every AI agent is a first-class actor with a verifiable KYA tier, spending limits, and cryptographic credentials. Not a shared service account.
  2. Policy enforcement. Agents transact under wallet policies that the network itself honors — kill-switches, per-merchant allowlists, daily caps, approval workflows.
  3. Protocol compatibility. Six agentic commerce protocols (UCP, ACP, AP2, x402, A2A, MCP) are supported behind one SDK — you integrate once and speak to any of them.

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Who this is for

Integration developers

Backend engineers at fintechs, marketplaces, and platforms integrating agentic payments into an existing product. You want REST, SDKs, webhooks, a sandbox, and a clean pk_test / pk_live split.

Agent builders

Developers shipping autonomous agents that need to pay for things. You want Ed25519 auth, MCP tools, A2A discovery, and wallet policies you can configure from code.

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Architecture at a glance

┌─────────────────────┐    ┌──────────────────────┐    ┌─────────────────┐
│   Your app / agent  │───▶│     Sly API          │───▶│  Payment rails  │
│   (SDK / CLI / MCP) │    │   (api.getsly.ai)    │    │  (stablecoin,   │
│                     │    │                      │    │   cards, banks) │
└─────────────────────┘    │  • Auth (5 methods)  │    └─────────────────┘
                           │  • Protocol adapter  │
                           │  • Policy engine     │
                           │  • Tenant isolation  │
                           │  • Webhook delivery  │
                           └──────────────────────┘
Your integration touches three surfaces:
SurfacePurposeWhen to use
REST APIFull programmatic accessServer-side integrations, backends
Node SDK (@sly_ai/sdk)Typed client with retry + authNode.js/TypeScript applications
CLI (@sly_ai/cli)Terminal + scriptingOps, scripts, CI/CD
MCP server (@sly_ai/mcp-server)Model Context ProtocolClaude Desktop, agent runtimes

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Core objects

Every integration works with a handful of core objects. Familiarize yourself with these before writing code:
  • Tenant — your organization. All data is tenant-scoped.
  • Account — a person or business that holds funds. Has a KYC tier.
  • Agent — an AI actor attached to an Account. Has a KYA tier and wallet policy.
  • Wallet — the actual fund-holding primitive; one per Account or Agent.
  • Transfer — a one-time movement of money.
  • Stream — a continuous per-second flow of money.
  • Quote — an expiring FX rate for cross-border moves.

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Next steps

Environments

Understand test vs. live and what data is isolated between them.

Sign up

Create your account and provision sandbox API keys.

Quickstart

First API call and first transfer in 5 minutes.

Authentication

The five auth methods and when to use each.