Quickstart

Agentcard lets your users connect their cards so their agent can make payments on their behalf using cards from the Agentcard Wallet. Your users add their cards once; from then on their agent pays merchants with a card from the wallet — the card details are handed to the agent just in time and are never stored by Linq.

• A Linq organization with API access. Create an API token at dashboard.linqapp.com/api-tooling and send it on every request as Authorization: Bearer <LINQ_API_KEY>.
• Base URL: https://api.linqapp.com/api/partner/v3.
• A webhook endpoint to receive payment and connection events (see Webhooks & lifecycle).

1. Connect the provider (once)

   Onboard your organization to Agentcard from the Linq dashboard — go to Payments and connect Agentcard. Do this a single time per org.

2. Connect a customer

   Start a connection for a customer handle (phone in E.164, or email). Linq drives the one-time code and consent through the messaging channel; hold the returned connect_id.

   curl -X POST https://api.linqapp.com/api/partner/v3/payments/handles/+14155550123/connect \
     -H "Authorization: Bearer $LINQ_API_KEY"

   When the customer replies with their code, complete the connection:

   curl -X POST https://api.linqapp.com/api/partner/v3/payments/handles/+14155550123/verify \
     -H "Authorization: Bearer $LINQ_API_KEY" \
     -H "Content-Type: application/json" \
     -d '{ "connect_id": "cs_01HZY8", "code": "482913" }'

   Full walkthrough with screens: Connect a customer.

3. Create a payment

   Call the payments endpoint with the handle, amount_cents, currency, and merchant. Send an Idempotency-Key so a retry never double-charges.

   curl -X POST https://api.linqapp.com/api/partner/v3/payments \
     -H "Authorization: Bearer $LINQ_API_KEY" \
     -H "Idempotency-Key: $(uuidgen)" \
     -H "Content-Type: application/json" \
     -d '{
       "handle": "+14155550123",
       "amount_cents": 2500,
       "currency": "usd",
       "description": "Burger order",
       "merchant": { "name": "DoorDash", "url": "doordash.com" }
     }'

   amount_cents: 2500 is $25.00 — amounts are always in the currency’s minor units.

4. Retrieve the card

   When the payment is ready, fetch the credential handoff. Your agent uses it to read the card directly from Agentcard — the number never passes through Linq.

   curl https://api.linqapp.com/api/partner/v3/payments/550e8400-e29b-41d4-a716-446655440000/credentials \
     -H "Authorization: Bearer $LINQ_API_KEY"

   See Cards & credentials for the handoff shape and how the agent redeems it.

5. Track the lifecycle

   Subscribe to webhooks instead of polling: payment.authorized, payment.declined, connection.created, and connection.revoked. Treat the event as a nudge and re-fetch the payment for authoritative status — there is no payment.succeeded webhook, so poll GET /payments/{id} for the final succeeded state.

• Amounts are in the currency’s minor units — amount_cents (cents for usd).
• A payment is idempotent on the Idempotency-Key header.
• Card credentials are fetched directly from Agentcard and are never stored by Linq.

• Connect a customer — connect and verify, with screens.
• Create & complete a payment — statuses and retrieval.
• Webhooks & lifecycle — events and payloads.
• Agentcard vs Stripe — pick the right rail.