> For the complete documentation index, see [llms.txt](https://doc.api.tieto.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.api.tieto.com/solutions-and-use-cases/aggregation.md).

# Financial API Aggregation

A third party that wants national coverage faces the same grind every time: a separate integration for every bank, separate certificates, separate quirks to maintain forever. Aggregation ends that. The Platform fronts the XS2A interfaces of banks that are not your tenants and presents them all behind one aggregated REST interface — the institution becomes a parameter of the call instead of a project of its own.

Every bank reads the Berlin Group specification a little differently: an optional parameter here, an extra payment type there, the same field interpreted two ways. The aggregation layer absorbs all of it, so the TPPs on your platform never have to. One integration, one certificate arrangement, one set of applications — and the whole market behind it.

## What you put on the shelf

Both the regulatory and the premium interfaces of external banks can be aggregated. The regulatory suite looks like this:

| Product                            | What it gives a TPP                                                                                         |
| ---------------------------------- | ----------------------------------------------------------------------------------------------------------- |
| **Aggregated Account Information** | Accounts, balances and transaction history across every connected bank, in one consistent shape             |
| **Aggregated Payment Initiation**  | Initiate a payment at any connected bank and follow its status through a single interface                   |
| **Aggregated Funds Confirmation**  | One yes-or-no answer on availability of funds, whoever holds the account                                    |
| **Aggregated Consents**            | Consent handling as a service in its own right — something no individual bank’s regulatory interface offers |

## The one open banking service you price yourself

Where national regulation says a bank’s compliance APIs are free of charge, they are free of charge. Aggregation is a different animal: it is a value-added service that goes beyond anything the regulation asks for, and it is yours to monetize. Limits and tariffs are set per aggregated product by you, the platform operator — not by the banks underneath and not by the regulator.

The same interfaces that are a pure cost center for every bank in the market become a revenue line for you.

## You decide which banks, and how fast

Adding a bank is not a Tieto project. The **Aggregation SDK** ships with the platform so your own developers can build, test and release new bank integrations on your schedule — which institutions, in what order, how quickly. Aggregation stops being something you buy and becomes something you operate.

{% stepper %}
{% step %}

### Point it at the bank’s specification

The target bank’s OpenAPI file is the only input you need.
{% endstep %}

{% step %}

### Let the generator do the groundwork

It produces the model for that bank’s interface and the configuration that registers it on the platform.
{% endstep %}

{% step %}

### Map only the differences

Your team describes where this bank’s reading of an operation differs from the aggregated one. Where a bank follows the standard closely, a ready-made openFinance strategy covers it and nothing is written at all.
{% endstep %}
{% endstepper %}

And because specifications in the real world are optimistic — banks return response variants their own documentation never mentions, which is the classic reason an integration breaks at two in the morning — fallback strategies catch what the primary mapping cannot. Coverage keeps working while someone gets around to correcting a document.

{% hint style="info" %}
A development team comfortable with Java and Maven, plus the target bank’s OpenAPI specification, is all it takes. Aggregating an external bank’s **regulatory** interfaces is covered by the standard license; aggregating its **premium** interfaces requires an extended one.
{% endhint %}

## Or let us run it for you

Not every operator wants to own an integration backlog. [Tieto SaaS Aggregation Platform](/solutions-and-use-cases/tieto-aggregation-service.md) is the same capability delivered as a managed service, with more than 200 banks across Europe already connected — one integration with us, and the coverage is there on day one.


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