Connect SumUp

Connect your own SumUp merchant account under Company settings > Payments. Use the same account for every credential and for the SumUp app or reader. Before activating a provider, make sure SumUp has enabled the payment product you plan to use.

Find Merchant ID / Merchant Code beside your name at the upper left (dashboard help). Name the key Calendia and copy or download it immediately. English menu: Settings > For Developers > Toolkit > API Keys. Use one business account; never email or chat the key.

Find the merchant code and API key

1. Sign in at me.sumup.com and open your profile to find the merchant code.
2. Open Settings > For Developers > Toolkit > API Keys, or go directly to API Keys.
3. Select Create, name the key for Calendia and copy the secret key. If you see only the SumUp Public Key, create an API key; the public key is not the secret API key Calendia needs.
4. In Calendia, enter the merchant code in Merchant code and the secret in API key. Save and activate the integration.

Treat the secret key like a password. Do not put it in messages, screenshots or public code. If you suspect exposure, revoke it in SumUp and replace it in Calendia.

Choose a device and check setup

SumUp syncs supported Solo readers; choose a default terminal per location if needed. SumUp Air hands payment to the SumUp iOS app on the same iPad, with the Air reader paired there. Tap to Pay (SumUp app) uses the SumUp app on the same phone and needs no separate reader. The Air and Tap to Pay options also require the same merchant code and secret API key.

Check that the integration is active and the intended reader or app is signed into the same merchant account before taking a payment. If a reader is missing, refresh the device list and check its connection. If authentication fails, compare merchant code and API key, then replace the key if necessary. Avoid a live test charge merely to validate setup.

SumUp API key instructions · SumUp terminal guide