Attach a merchant to a shared connection

post

https://api.justt.ai/v1/integrations/{integrationId}/join-integration

Adds a merchant to a connection that Justt has already shared between merchants, and records the values that route chargebacks to it. Requires an account-scoped API key.

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Path Params

integrationId

string

required

The id of the shared connection to attach the merchant to

Body Params

merchantUuid

string

required

The merchant to attach to the connection

routing

array of objects

required

One entry per field this merchant is identified by. A merchant joins a connection once, so every rule it needs must be sent together.

routing*

goLiveDate

date

^\d{4}-\d{2}-\d{2}$

The date this merchant starts fighting chargebacks on the connection.

Optional. Leave it out and the platform uses 5 days from today, the same default it applies when nobody names a date.

Format: a calendar date on its own, YYYY-MM-DD, for example 2026-10-01. A value carrying a time is refused, whether or not it names a timezone — 2026-10-01T00:00:00Z and 2026-10-01T01:00:00+05:00 both return 400. A go-live date names a day; a time with an offset names an instant, and that instant can fall on the day before or after in UTC. 2026-10-01T01:00:00+05:00 is 30 September in UTC, so rather than store a day you did not write, we refuse it.

Range: between tomorrow and 90 days ahead, measured against the current UTC date. Day 90 is allowed, day 91 is not. Today and any earlier date are refused: backdating pulls chargebacks the connection already received into scope, and stays a Justt-only action.

Calendar: the day has to exist. 2026-02-30 and 2027-02-29 return 400 rather than rolling over into the following month.

In the response this field comes back as a full UTC timestamp at midnight, for example 2026-10-01T00:00:00.000Z. Check it against what you meant to send.

Responses

201The merchant was attached to the connection

401The API key is not account-scoped. A merchant- or group-scoped key cannot reach this endpoint, because a shared connection belongs to no single merchant.

404No such connection or merchant on this account. A connection that is deleted or deactivated answers the same way, because neither can take a merchant.

409The merchant is already attached to this connection, or was attached and then deactivated, or one of the key values already belongs to another merchant on the field it was sent under.

500In the message you can find explanation of what went wrong, please provide the error ID for our support for future investigation if needed