diff --git a/src/delta_barth/_csharp/json_types.py b/src/delta_barth/_csharp/json_types.py
new file mode 100644
index 0000000..112299b
--- /dev/null
+++ b/src/delta_barth/_csharp/json_types.py
@@ -0,0 +1,53 @@
+from delta_barth.api.requests import (
+    SalesPrognosisResult,
+    SalesPrognosisResults,
+    SalesPrognosisResultsExport,
+)
+from delta_barth.errors import STATUS_HANDLER
+from delta_barth.types import (
+    ApiCredentials,
+    DelBarApiError,
+    Status,
+)
+
+
+def sales_prognosis_result() -> str:
+    model = SalesPrognosisResult(jahr=2023, monat=12, vorhersage=3000.3456)
+    return model.model_dump_json()
+
+
+def sales_prognosis_results() -> str:
+    e1 = SalesPrognosisResult(jahr=2023, monat=12, vorhersage=3000.3456)
+    e2 = SalesPrognosisResult(jahr=2024, monat=1, vorhersage=3300.685)
+    e3 = SalesPrognosisResult(jahr=2024, monat=2, vorhersage=3700.548)
+    res = (e1, e2, e3)
+    model = SalesPrognosisResults(daten=res)
+    return model.model_dump_json()
+
+
+def sales_prognosis_results_export() -> str:
+    status = STATUS_HANDLER.SUCCESS
+    e1 = SalesPrognosisResult(jahr=2023, monat=12, vorhersage=3000.3456)
+    e2 = SalesPrognosisResult(jahr=2024, monat=1, vorhersage=3300.685)
+    e3 = SalesPrognosisResult(jahr=2024, monat=2, vorhersage=3700.548)
+    res = (e1, e2, e3)
+    results = SalesPrognosisResults(daten=res)
+    model = SalesPrognosisResultsExport(response=results, status=status)
+    return model.model_dump_json()
+
+
+def delta_barth_api_error() -> str:
+    err = DelBarApiError(status_code=401, message="test message", code="test code")
+    return err.model_dump_json()
+
+
+def status_err() -> str:
+    status = Status(code=102, description="internal error occurred", message="caused by test")
+    return status.model_dump_json()
+
+
+def api_credentials() -> str:
+    model = ApiCredentials(
+        user_name="user", password="pass", database="test1", mandant="mandant1"
+    )
+    return model.model_dump_json()