Agent signup

An AI agent can open a Free Arche account for the person it works for and start calling the API at once. It needs no browser and no card, only its owner’s real email address.

Open an account

Send the owner’s email and a name for the agent. No credentials are needed.

curl -X POST "https://api.arche.fi/v1/agent/signup" \
  -H "Content-Type: application/json" \
  -d '{"email": "owner@yourcompany.com", "agent_name": "research-assistant"}'

The response returns the key once:

{
  "data": {
    "api_key": "ak_test_…",
    "plan": "free",
    "owner_email": "owner@yourcompany.com",
    "owner_notified": true,
    "expires_at": "2026-10-25T09:30:00Z",
    "claim_url": "https://app.arche.fi/sign-up",
    "checkout_link_endpoint": "/v1/agent/checkout-link"
  }
}

Store api_key at once: it cannot be retrieved again. Send it in the X-Api-Key header, as on any other request. The Free plan is sandbox-only, so this is a sandbox key; it reads the same data as a production key.

If the key is lost before the owner takes over the account, sign up again with the same email. The old key stops working and a new one is returned. The owner is not emailed again.

The owner takes over

Arche emails the owner an invitation to the account. When the owner signs up at claim_url with the same email, the account becomes theirs, the agent’s key keeps working, and from then on keys are managed at app.arche.fi/keys.

Until the owner signs up, the key works for 14 days from the first signup and then returns 401 AGENT_ACCOUNT_UNCLAIMED. Signing up again does not extend it. Tell the owner to check their email, or send them claim_url.

When a call needs a paid plan

An error that a paid plan would lift carries details.checkout_link_endpoint. This applies to FEATURE_NOT_AVAILABLE, to COVERAGE_SELECTION_FULL (the Free plan covers 25 companies you choose) and to MONTHLY_QUOTA_EXCEEDED. Request a payment link for the owner:

curl -X POST "https://api.arche.fi/v1/agent/checkout-link" \
  -H "X-Api-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"plan": "developer", "interval": "month"}'

plan is developer, growth or scale, and interval is month or year. Both are optional and default to Developer, billed monthly. The response carries checkout_url, with the plan and its price in minor units.

Send checkout_url to the owner. The page asks them to sign in, or sign up with the account’s email, before they pay. A paid plan includes production keys, which the owner creates at app.arche.fi/keys. An account that already has a subscription gets 409 CHECKOUT_UNAVAILABLE, and its owner changes plan in the dashboard.

Over MCP, the account_checkout_link tool returns the same link, and MCP errors carry the same details.

Limits

• One account per email address, and one invitation per address.
• An email that already has an Arche login is refused. Its owner creates a key in the dashboard instead.
• Five signups per day from one IP address.
• Placeholder addresses such as example.com are refused.
• The Free plan’s limits apply: 25 companies you choose, and 2,000 requests a month.

Errors