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When a checkout reaches a final state, Float sends a single POST to the notify_url you supplied on create checkout. This page is the wire contract; the callbacks guide covers handler implementation, verification code, and local testing.

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Request

Method: POST · Content-Type: application/json

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Body

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status
string
required
successful or cancelled. There is no failed — the shopper can retry on the hosted page until they succeed or abandon, so a failed attempt is not final.
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amount
integer
required
The full payable amount in pence, exactly as sent when the checkout was created.
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currency
string
required
ISO 4217 code (GBP), as sent on the checkout.
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client_reference_id
string
required
Your reference from the checkout request, echoed verbatim. Use this to find the order on your side.
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number_of_payments
integer
required
The instalment term the shopper selected on the payment page (1 = once-off).
The callback does not include the checkout ID. Store the mapping client_reference_id → checkout_id when you create the checkout — you’ll need the ID for status lookups and refunds.

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Your response

Respond 2xx quickly (do fulfilment work async). Any 2xx counts as delivered, but returning JSON unlocks an optional feature:
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redirect_url
string (url)
If present and non-empty in your JSON response, Float sends the shopper’s browser here instead of the checkout’s success_url / cancel_url — useful for order-specific confirmation pages created during callback handling.
Return {} (or anything else with a 2xx) to use the default redirect.

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Delivery semantics

Callbacks can be missed (your endpoint down for longer than the retry window). Reconcile any order still pending after ~1 hour with GET /api/checkouts/:id — never leave paid orders unfulfilled because a webhook was dropped.