> For the complete documentation index, see [llms.txt](https://docs.altum.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.altum.ai/english/platform/kadaster-transaction-api-subscription.md).

# Kadaster Transaction API subscription

**What is the Kadaster Transaction API?**

The Transaction API is a paid service where transaction data can be requested from the Kadaster for a home. Check out the documentation below.

{% content-ref url="/pages/-MhMyhJrqm7Rd5GLJsPV" %}
[Kadaster Transaction API](/english/property-valuation-and-market/kadaster-transaction-api.md)
{% endcontent-ref %}

**Why is there a separate subscription for this API?**

The costs for requesting transaction data and purchase price information are higher than for the other APIs that Altum AI offers. 

**How does pay per use work for the Transaction API?**

With pay per use it is possible to make unlimited use of Altum AI's Transaction API. Each API call costs one credit, and a credit costs € 0,75 exclusive of VAT. The Pay per use usage is tracked in the Dashboard and settled monthly in arrears. 

**How do I avoid unnecessary costs when using the API?**

Eg. if no transaction is (yet) known. It is possible to 'ping' the Transaction API on the presence of the requested data. To do this, send an API call as usual, only not on api.altum.ai/transaction but on api.altum.ai/transaction/ping. With a positive feedback on this request, you can run the API call at the usual URL. The use of the ping function is unlimited and is not counted as paid usage. 


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