API Documentation


About Finexpay

Finexpay is a digital deferred or installment B2B payment solution. Finexpay can be used by any operator that generates or manages B2B transactions like merchants, marketplaces, payment service providers, and neobanks (our "Partners"). Once set up, Finexpay will allow the Buyers ("Buyers") to simply buy now and pay later (e.g., up to 90 days in addition to contractual payment terms) while the sellers ("Merchants") benefit from a guaranteed and immediate payment.

How does it work?

Finexpay is flexible enough to fit your business.

Once you create your Partner account on the Finexpay’s sandbox, you will be able to test our API. For example, Finexpay allows your Buyers to buy on your platform, and pay later with a delay of 30, 60 or 90 days. That’s just a beginning, we will help you to tailor the Finexpay products that you will offer to your Buyers.

Financing process is quite simple:

  • At checkout, you initiate a Payment session, with order informations,
  • The Buyer logs in or registers on our system, it chooses the Product it wants to use, then it validates the payment and conditions,
  • Finexpay grants the payment and notify your system by webhook,
  • Your Merchant checks its stock, prepares shipment then validates the Transaction. You then validate it on our system.
    If you don’t need this step, for example because all checks are connected and completed before order payment, no matter, you can set an automatic validation option,
  • We pay the Merchant,
  • Finally, when the financing term occurs, we get payment directly from the Buyer.

During the lifetime of Payment sessions and Transactions, you will get webhook notifications each time a change occurs, you won’t miss any information or event.


User journey

Once the Buyer validates its order on your platform, it can choose to pay with Finexpay, even if it’s not registered with Finexpay. You just have to initiate a payment session with accurate information and redirect the Buyer to the URL we give you in the response.

Then the Buyer will:

  • choose the deferred payment option it prefers,
  • authenticate to our systems,
  • confirm the payment, with clear information about the total cost,
  • be redirected back to your platform.

Note: if the Buyer uses Finexpay for the first time, it will be asked to register and create an account, and send standard KYC documents.

What do you have to do to use Finexpay?

First of all, you may register to get your dedicated sandbox environment.

As a sandbox Partner, you are granted to a default products set, containing deferred payment with 30, 60 and 90 days delay you can test right away.

We will help you to tailor your products set, with exclusive parameters such as economics of the Transactions or deferred payment options for the production environment.

Where can Finexpay operate?

We are operational with Buyers established throughout the European Economic Area regardless of the place of establishment of the Merchants and Partners. Do not hesitate to reach out to us if you want to operate in another country.

Our Terms and definitions

  • Partner: a B2B Merchant, commerces, ecommerces, marketplaces, payment service providers and neobanks that wishes to provide a buy now, pay later solution to its professional Buyers. The Partner is the entity that integrates and operates Finexpay APIs.
  • Merchant: a company using the Partner’s platform to provide services or goods to Buyers. A Merchant has to be a registered company or an independent worker. A Merchant has to be onboarded by the Partner in our system to use Finexpay. Occasionally, the Merchant may be the same entity as the Partner.
  • Buyer: an entity using the Partner’s platform to buy services or goods. A Buyer has to be a registered company or an independent worker whose profile is visible in public databases. A Buyer needs to create an account on Finexpay to get the ability to finance its orders.
  • Payment session: A Payment session is a request, for a Buyer, to get a deferred payment, with Finexpay, for its order on the Partner’s platform. It’s a bunch of one or more Transaction(s).
  • Transaction: A Transaction is a component of the Payment session, which contains one or many Transactions. When the order financed by the Payment session refers to many items sold by many Merchants, the Payment session must contain at least a Transaction by Merchant. Indeed, a Transaction refers to a unique Merchant.
  • Product: a specific configuration of the Finexpay solution. A Product is specified with various parameters, such as a loan type (deferred payment up to 90 days or split payments), a loan duration (30, 60 or 90 days), a loan fee structure… Remember: we will help you to tailor your Products set for the Production environment.

How to start

Finexpay APIs shall be used in the following order:

Create your account

Create your account and start to personalize your sandbox environment.

Then, you can immediately try our API. You may take a look at the sandbox’s configuration settings such as webhooks, API keys…

Create the Merchant

First thing, you need to create the Merchant in our system. When created, you will receive a MerchantId. This MerchantId needs to be stored in rthe Partner's system as you will need it to initiate a Transaction and to perform actions with the Merchant. You can always find the MerchantId and other info about your Merchants with :

It may well be that the Partner and the Merchant are the same entities (e.g., direct B2B e-commerce websites), in which case you will only need to create your own Merchant account after integrating Finexpay.

Upload the bank details

When a Transaction is financed, Finexpay does a payout in order to make the Merchant paid immediately. This is proceeded by a SCT (SEPA Credit Transfer) on an account identified by its IBAN. Two ways of working exist:

Let’s do it

Initiate a Payment session...

When a Buyer chooses to pay the order it did on your system, you must first create a Payment session with, at least, one Transaction. Each Transaction must include at least the mandatory information required to identify the order and the Merchant. Finexpay will then return an URL to redirect the Buyer to Finexpay’s interface.

... You then redirect the Buyer to Finexpay’s checkout page

Depending on the available Products, the Buyer will select between the Finexpay payment options offered. You have nothing else to do, Finexpay will manage everything. The Buyer will be guided to login or create its account if necessary. In case of registration, we will require some regulatory documents such as KYC, it’s included in our registration process. The Buyer will see the exact cost of the deferred payment option and will validate the Payment session. Finally, the Buyer will be redirected to the callback URL you previously gave us to return to your platform.

Please note that the Buyer has to accept or refuse a Payment session within a specific timeout. Default timeout value is 30 minutes, but you can send us a personalized timeout value in the create a Payment session API endpoint.

Initiate a Payment session without UI

Finexpay offers another way to initiate a Payment session with full API mode, without the checkout process UI.

With the Initiate a new Payment session with no ui API endpoint, you will provide all necessary information such as Buyer’s identifier, Product’s identifier, and you will get Finexpay’s response as a result of the API call.

To do such a Payment session, you may be authorized by a delegation given by the Buyer. There are two conditions:

  • You have been granted by Finexpay to initiate this kind of Payment session,
  • The Buyer has accepted specific contract terms where it delegates the validation of its Finexpay payments to you, the Partner.

Cancel a Payment session or a Transaction

It can happen that the Buyer finally changes its mind and decides to cancel the order it did on your system. Nothing is easier than Canceling a Payment session.

The Merchant is not able to ship the item to the Buyer, no worry, just call the Cancel a Transaction API endpoint. Cancellation can be done before validation, when Transactions are already financed, you may need to Add a credit note.

Notification of the Payment session’ status

The Buyer can decide to accept, refuse or leave the Payment session. Depending on its choice, the Buyer will then be redirected to the callback url that you gave when creating a Payment session. You will also be notified by a webhook about the Payment session’ status. Finexpay has to accept or refuse a Payment session within a time frame of 48 hours.

Validate the Transaction

Once the Payment session is accepted by the Buyer and validated by Finexpay, it has to be validated by your system. This step allows you to confirm that all internal processes have been completed successfully, such as stock control, shipment etc. You may call the Validate Transaction Request API endpoint within the validation time frame, decided with Finexpay in the contractual settings, or 48 hours by default.

Note that you’re also able to initiate a Payment session where Transactions are automatically validated. It may be useful if your system does all checks before going to the checkout process.

Please refer to the TransactionRequest object to get more information.

Notification of the Transaction’ status

When a Transaction is financed, it gets its own life, you will get status updates on the Transaction’ status webhook.

You will get notified for the following events:

  • The Transaction is validated and financed
  • The Transaction was not validated in the specified timeframe by the Merchant,
  • The payment from the Buyer is successful
  • The payment from the Buyer failed

Payment to the Merchant

Once a Transaction is validated by the Merchant, Finexpay starts its financing.

  • We register a future payment at the delay chosen by the Buyer.
  • We pay the Merchant with a SCT, according to the payment options that have been configured.

Payments to Merchants are done once a day with all transactions of the day, we also deduce credit notes that have been recorded. You get a webhook notification with all the necessary details to make the reconciliation process easy on your side.

You can also retrieve the Merchant payments details by calling the Payout endpoints.

Add a credit note on Transaction

Once the Payment session is validated, and its Transaction(s) financed, you cannot cancel it, but it happens that the Buyer returns the items it received, or for any other reason, you may need to reduce the Transaction amount finally due.

This is why you can add a credit note to any alive Transaction:

  • We will automatically reduce the due amount for this Transaction by the credit note amount,
  • We will adjust the calculation of interests due by the Buyer. Note that in any case, the Buyer won’t have to pay a higher amount than the accepted financing conditions,
  • We will hold back the amount of the credit note in the next Merchant payment, the webhook notification will contain necessary information to understand how it’s calculated.

Let’s rock

You can contact our customer service by email info@finexpay.com or by phone at +33 9 74 19 05 00. Our team will work with you to tailor your Partner profile and sign the relevant cooperation agreement with Finexpay. Remember that it is possible to configure several Products for your platform.

Risk assessment and management of a Transaction

Finexpay can instantly assess the risk pertaining to a Transaction but, in some rare instances, Finexpay may need more time to validate the Transaction. This can happen, for example, when a Buyer first registers with Finexpay (first connection). In order to comply with AML (anti-money laundering) regulations, Finexpay has to collect the UBOs (Ultimate Beneficial Owners) of the Buyer.

In order to provide the best user experience and facilitate the Buyer registration, Finexpay has developed a unique feature to automatically collect the required documentation. This operation can take up to 24 open hours. Please note that, in order to better fit your checkout process, we can pre-register your Buyers to collect this documentation before their registration (subject to discussion).

Please note that Finexpay services include the following: (i) collecting on short-term loans used to finance Transactions (so that Partners and Merchants are relieved from collecting on payments made through Finexpay), (ii) automatic reconciliation of payments, financings and Transactions, and (iii) transfer to Finexpay of 95% of the insolvency risk attached to the Buyers (the remaining 5% being borne by the relevant Merchant(s)).