I think you can connect to On-Premise Celonis API, however if it was build for cloud version it probibly won't work because of different API layout / objects and much smaller number of methods to use. It also depends on which version of the system is available, there will be differences in 4.3 or 4.6.1..

I've attached PDF regarding this topic, hopw it helps - share with update. :)

How i can confirm API that i'm using in my solution is also supported on Premisses? Is there any documentation that list APIs available only of on-premises? or API not available on on-premises installation? Mostly i'm using API to execute PQL which i assume is well supported in both environment.

As I've previously wrote - the API is available. In my prevoius post you can find API manual from Celonis for 4.6.1 On-premise version of the solution, required version is located on second page. Unfortunatelly, I've missed it's only the User Management and Authorization Management part of API.

Please note that PQL code was changed mutliple times. Because of that many PQL statements that are avaiable in cloud are not available in On-Premise Celonis or works differently. Just because that, old code may not work. You need just to go throught the python code, check which PQL statements are used, and check if they are avaiable in on-premise solution. Checking specific API documentation will be also good idea.

Depending on version of on-premise Celonis, you will use different API version:

-CPM 4.5 uses API tools 1.0 (Documentation: https://support.celonis.de/x/NIcnAQ)

-CPM 4.3 and 4.3.1 uses API tools 0.6.1 (Documentation: https://support.celonis.de/x/JocnAQ)

-CPM 4.3 and 4.3.1 - when doing only data transfer (pushing/retrieving data to Celonis), the additional pyorcloader package is recommended (only necessary for for those two. Documentation: https://support.celonis.de/x/GYcnAQ)

I've briefly checked the API 1.0 documentation for CPM 4.5 Celonis system and i can see that you can send some queries to pull the data (attached screenshot)