A very common specialism in CRM development is integration with other systems such as SAP and Exact, for example to keep contact and invoicing data synchronous, but also to enrich data in CRM with data from, for example, a postal code supplier, the land register, the insolvency register, and so on. In addition, it is also very common to link customer portals and all kinds of customized software to CRM.
These integrations are almost always done through SOAP or REST web services which take care of the data transport from one system to another. Nowadays, generally speaking there is also a lot of talk of Microservices Architecture, which is in fact the same.
We have a lot of experience with integrating to external systems from CRM but also with building custom software with which third parties can edit data in CRM in their own way. An external party can thus connect with CRM with a specific data model.
When an external party has its own development capacity, they can of course use the CRM API, but that can become quite complicated if you have little technical knowledge and a user license has to be purchased for that user.
Feel free to contact us to see what we can do for your company.