All IDs that you need to use for the API (except for the participant ID) are uppercase GUIDs in the format 8-4-4-4-12 characters, which generally look like:

93852ECC-18F1-4829-A453-87B924B08D84

• The study ID can be found in the study settings in Castor CDMS or with the endpoint

/study

• Participant IDs are the same as they are listed in the Participants tab in your study.
• All other IDs (e.g. field, Repeating Data (instance), survey (package instance)) can be found with the endpoints as listed in the API documentation. For example, you can find a field ID with the endpoint.

/study/{study_id}/field