Authentication

API Keys

y0 uses API keys for authentication. API keys are scoped to a tier (Free, Growth, Business, Enterprise).

Getting an API Key

Sign up at y0.exchange/business
Create a new project
Generate an API key (prefix: y0_)
Set it as an environment variable

Using Your API Key

MCP Server:

{
  "mcpServers": {
    "y0": {
      "command": "npx",
      "args": ["@y0exchange/mcp"],
      "env": {
        "Y0_API_KEY": "y0_your-api-key"
      }
    }
  }
}

REST API:

curl -H "Authorization: Bearer y0_your-api-key" \
  https://api.y0.exchange/v1/balance?address=0xd8dA...

Sessions

For write tools, the signing service creates sessions that link an API key to a user’s wallet address.

Session Management

POST /api/sessions       — Create session (returns session ID + API key)
GET  /api/sessions       — List active sessions
DELETE /api/sessions/:id — Revoke session

Session Properties

Property	Description
`id`	Unique session ID
`userAddress`	Linked wallet address
`apiKeyHash`	Hashed API key (never stored in plain text)
`permissions`	JSON: allowed tools, chains, token pairs
`spendingLimits`	JSON: per-tx and daily USD limits

Rate Limits

Tier	Rate Limit	Monthly Limit
Free	10 req/min	Unlimited
Growth	60 req/min	Unlimited
Business	300 req/min	Unlimited
Enterprise	Custom	Unlimited

Security

API keys are hashed (SHA-256) before storage
All API traffic is HTTPS-only
Sessions can be revoked at any time
Spending limits are enforced server-side
Users can disconnect wallet and revoke all sessions

OpenAI Function Calling Pricing