Create checkout session

post

https://api.ekko.earth/v3/checkout/sessions

Create a checkout session for the Checkout SDK.

The response carries the three values your frontend passes to the SDK (sessionId, clientSecret and sessionData). Keep sessionId against the order for your own records. The quote is worked out when the consumer's browser loads the checkout.

The quoteId reaches your page through the SDK's events. Send it to your server with the order and allocate against it with POST /funds/allocations.

Body Params

organisationId

uuid

required

consumer

object

required

The consumer making the transaction.

merchant

object | null

Required if an MCC was not provided during organisation onboarding.

If the organisation has an MCC set, you can omit the merchant object.

transaction

object

required

orderItems

array of objects | null

orderItems

projectFilters

object | null

impactType

string

enum

The impact calculation type. carbon returns a carbon footprint and carbon credit pricing. nature returns a biodiversity (Nature Footprint) calculation in Mean Species Abundance (MSA) and contribution pricing. Defaults to carbon when omitted.

Allowed:

locale

string

Defaults to en-GB

BCP 47 locale tag for the quote, such as en-GB. It sets the language of the copy the quote carries, including the footprint equivalents and the impact partner text. Defaults to en-GB, which is also the fallback when the requested locale is not supported. The Checkout SDK's own locale option takes precedence for the component's translations, price formatting and text direction. It does not trigger a new quote, so this locale still sets the language of the quote payload.

Headers

Ekko-Version

string

required

^\d{4}-\d{2}-\d{2}\.[a-z]+$

Defaults to 2026-10-06.pangolin

The API version the request was built against, as YYYY-MM-DD.animal. Required on every request. See Versioning.

Responses

201Session created

400Bad request

401Unauthorised

404Not found

409Conflict. The request conflicts with the current state of the resource.

422Unprocessable entity. The request was understood but cannot be processed as asked.

500Server error

503Service unavailable. The upstream service could not be reached, so the request was not performed.