diff --git a/datamodel_code_generator/__init__.py b/datamodel_code_generator/__init__.py
index b78d25f8..55285754 100644
--- a/datamodel_code_generator/__init__.py
+++ b/datamodel_code_generator/__init__.py
@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import contextlib
 import os
+import sys
 from datetime import datetime, timezone
 from enum import Enum
 from pathlib import Path
@@ -308,6 +309,10 @@ def generate(
                 if is_openapi(input_text_)  # type: ignore
                 else InputFileType.JsonSchema
             )
+            print(
+                f'The input file type was determined to be: {input_file_type.value}',
+                file=sys.stderr,
+            )
         except:  # noqa
             raise Error('Invalid file format')
 

diff --git a/tests/test_main.py b/tests/test_main.py
index d5ce25d1..1f9a5bce 100644
--- a/tests/test_main.py
+++ b/tests/test_main.py
@@ -588,7 +588,7 @@ def test_main_no_file(capsys: CaptureFixture) -> None:
     assert (
         captured.out == (EXPECTED_MAIN_PATH / 'main_no_file' / 'output.py').read_text()
     )
-    assert not captured.err
+    assert captured.err == 'The input file type was determined to be: openapi\n'
 
 
 def test_main_extra_template_data_config(capsys: CaptureFixture) -> None:
@@ -614,7 +614,7 @@ def test_main_extra_template_data_config(capsys: CaptureFixture) -> None:
             EXPECTED_MAIN_PATH / 'main_extra_template_data_config' / 'output.py'
         ).read_text()
     )
-    assert not captured.err
+    assert captured.err == 'The input file type was determined to be: openapi\n'
 
 
 def test_main_custom_template_dir_old_style(capsys: CaptureFixture) -> None:
@@ -641,7 +641,7 @@ def test_main_custom_template_dir_old_style(capsys: CaptureFixture) -> None:
         captured.out
         == (EXPECTED_MAIN_PATH / 'main_custom_template_dir' / 'output.py').read_text()
     )
-    assert not captured.err
+    assert captured.err == 'The input file type was determined to be: openapi\n'
 
 
 def test_main_custom_template_dir(capsys: CaptureFixture) -> None:
@@ -668,7 +668,7 @@ def test_main_custom_template_dir(capsys: CaptureFixture) -> None:
         captured.out
         == (EXPECTED_MAIN_PATH / 'main_custom_template_dir' / 'output.py').read_text()
     )
-    assert not captured.err
+    assert captured.err == 'The input file type was determined to be: openapi\n'
 
 
 @freeze_time('2019-07-26')
diff --git a/tests/test_main_kr.py b/tests/test_main_kr.py
index ca261f59..d8949825 100644
--- a/tests/test_main_kr.py
+++ b/tests/test_main_kr.py
@@ -146,7 +146,7 @@ def test_main_no_file(capsys: CaptureFixture) -> None:
         == (EXPECTED_MAIN_KR_PATH / 'main_no_file' / 'output.py').read_text()
     )
 
-    assert not captured.err
+    assert captured.err == 'The input file type was determined to be: openapi\n'
 
 
 def test_main_custom_template_dir(capsys: CaptureFixture) -> None:
@@ -175,7 +175,7 @@ def test_main_custom_template_dir(capsys: CaptureFixture) -> None:
             EXPECTED_MAIN_KR_PATH / 'main_custom_template_dir' / 'output.py'
         ).read_text()
     )
-    assert not captured.err
+    assert captured.err == 'The input file type was determined to be: openapi\n'
 
 
 @freeze_time('2019-07-26')

(🎁) Log input file type when when `--input-file-type` is `auto`
I was left a little confused when my json file was silently detected as jsonschema instead of json.
tests/test_main.py::test_main_extra_template_data_config tests/test_main.py::test_main_no_file tests/test_main.py::test_main_custom_template_dir tests/test_main.py::test_main_custom_template_dir_old_style tests/test_main_kr.py::test_main_custom_template_dir tests/test_main_kr.py::test_main_no_file
tests/test_main.py::test_main_generate_custom_class_name_generator tests/test_main.py::test_external_relative_ref tests/test_main.py::test_main_with_bad_aliases tests/test_main.py::test_main_json_arrary_include_null tests/test_main.py::test_main_json_failed tests/test_main.py::test_main_null_and_array tests/test_main.py::test_main_nested_directory tests/test_main.py::test_jsonschema_pattern_properties tests/test_main.py::test_main_all_of_ref tests/test_main.py::test_main_openapi_nullable_use_union_operator tests/test_main.py::test_main_with_aliases tests/test_main.py::test_main_jsonschema_boolean_property tests/test_main.py::test_jsonschema_pattern_properties_field_constraints tests/test_main.py::test_main_multiple_required_any_of tests/test_main.py::test_main_json_pointer tests/test_main.py::test_main_openapi_reference_to_object_properties_collapse_root_models tests/test_main.py::test_validation tests/test_main.py::test_main_invalid_enum_name_snake_case_field tests/test_main.py::test_jsonschema_titles_use_title_as_name tests/test_main.py::test_show_help_when_no_input tests/test_main.py::test_main_original_field_name_delimiter_without_snake_case_field tests/test_main.py::test_main_strict_types tests/test_main.py::test_main_jsonschema_field_extras_field_include_all_keys tests/test_main.py::test_main_openapi_all_of_required tests/test_main.py::test_main_json_reuse_enum tests/test_main.py::test_main_collapse_root_models_field_constraints tests/test_main.py::test_main_jsonschema_reference_same_hierarchy_directory tests/test_main.py::test_force_optional tests/test_main.py::test_main_jsonschema_special_enum tests/test_main.py::test_main_jsonschema_special_enum_empty_enum_field_name tests/test_main.py::test_main_jsonschema_complex_one_of tests/test_main.py::test_main_json_snake_case_field tests/test_main.py::test_main_external_definitions tests/test_main.py::test_main_invalid_enum_name tests/test_main.py::test_main_openapi_max_items_enum tests/test_main.py::test_main_invalid_model_name_failed tests/test_main.py::test_main_models_not_found tests/test_main.py::test_main_jsonschema_id tests/test_main.py::test_main_generate tests/test_main.py::test_main_invalid_model_name tests/test_main.py::test_main_jsonschema_ids tests/test_main.py::test_main_jsonschema_id_as_stdin tests/test_main.py::test_main_jsonschema_multiple_files_ref_test_json tests/test_main.py::test_disable_timestamp tests/test_main.py::test_main_yaml tests/test_main.py::test_main_dataclass_field tests/test_main.py::test_main_jsonschema_field_extras tests/test_main.py::test_main tests/test_main.py::test_main_openapi_json_pointer tests/test_main.py::test_long_description tests/test_main.py::test_main_without_field_constraints tests/test_main.py::test_main_jsonschema_json_pointer_array tests/test_main.py::test_main_jsonschema_special_model_remove_special_field_name_prefix tests/test_main.py::test_main_root_id_jsonschema_with_absolute_local_file tests/test_main.py::test_main_jsonschema_enum_root_literal tests/test_main.py::test_version tests/test_main.py::test_main_jsonschema_nested_skip tests/test_main.py::test_main_modular tests/test_main.py::test_jsonschema_titles tests/test_main.py::test_target_python_version tests/test_main.py::test_main_json_capitalise_enum_members tests/test_main.py::test_main_json tests/test_main.py::test_main_disable_warnings tests/test_main.py::test_enable_faux_immutability tests/test_main.py::test_main_use_default_kwarg tests/test_main.py::test_allow_extra_fields tests/test_main.py::test_main_all_of_with_object tests/test_main.py::test_main_nullable_any_of tests/test_main.py::test_main_autodetect tests/test_main.py::test_main_openapi_body_and_parameters_only_schemas tests/test_main.py::test_main_nested_all_of_ tests/test_main.py::test_main_jsonschema_multiple_files_json_pointer tests/test_main.py::test_main_jsonschema_combine_one_of_object tests/test_main.py::test_main_openapi_discriminator tests/test_main.py::test_main_jsonschema_duplicate_name tests/test_main.py::test_main_pydantic_basemodel tests/test_main.py::test_main_openapi_reference_to_object_properties tests/test_main.py::test_main_jsonschema_array_in_additional_properites tests/test_main.py::test_enable_version_header tests/test_main.py::test_main_jsonschema_modular_default_enum_member tests/test_main.py::test_main_jsonschema_special_field_name tests/test_main.py::test_main_jsonschema_multiple_files_ref tests/test_main.py::test_main_strict_types_all_with_field_constraints tests/test_main.py::test_main_generate_custom_class_name_generator_additional_properties tests/test_main.py::test_main_use_standard_collections tests/test_main.py::test_main_jsonschema_pattern_properties_by_reference tests/test_main.py::test_csv_stdin tests/test_main.py::test_main_jsonschema_nested_deep tests/test_main.py::test_main_jsonschema_subclass_enum tests/test_main.py::test_main_openapi_body_and_parameters tests/test_main.py::test_main_base_class tests/test_main.py::test_allow_population_by_field_name tests/test_main.py::test_main_nullable_any_of_use_union_operator tests/test_main.py::test_main_root_model_with_additional_properties tests/test_main.py::test_csv_file tests/test_main.py::test_main_jsonschema_nullable_object tests/test_main.py::test_main_jsonschema_special_enum_special_field_name_prefix tests/test_main.py::test_main_with_exclusive tests/test_main.py::test_main_space_field_enum_snake_case_field tests/test_main.py::test_main_inheritance_forward_ref tests/test_main.py::test_stdin tests/test_main.py::test_main_openapi_body_and_parameters_only_paths tests/test_main.py::test_validation_failed tests/test_main.py::test_space_and_special_characters_dict tests/test_main.py::test_main_root_model_with_additional_properties_use_standard_collections tests/test_main.py::test_main_autodetect_failed tests/test_main.py::test_main_jsonschema_object_has_one_of tests/test_main.py::test_main_generate_custom_class_name_generator_modular tests/test_main.py::test_main_jsonschema_field_include_all_keys tests/test_main.py::test_use_default tests/test_main.py::test_main_modular_no_file tests/test_main.py::test_main_dataclass tests/test_main.py::test_main_openapi_default_object tests/test_main.py::test_openapi_special_yaml_keywords tests/test_main.py::test_main_openapi_pattern tests/test_main.py::test_main_nested_enum tests/test_main.py::test_main_disable_appending_item_suffix tests/test_main.py::test_main_openapi_datetime tests/test_main.py::test_main_root_model_with_additional_properties_use_generic_container_types tests/test_main.py::test_main_openapi_complex_reference tests/test_main.py::test_main_similar_nested_array tests/test_main.py::test_main_use_annotated_with_field_constraints tests/test_main.py::test_main_json_capitalise_enum_members_without_enum tests/test_main.py::test_main_with_more_bad_aliases tests/test_main.py::test_main_jsonschema_external_files tests/test_main.py::test_main_jsonschema_pattern tests/test_main.py::test_jsonschema_without_titles_use_title_as_name tests/test_main.py::test_main_with_field_constraints tests/test_main.py::test_main_json_reuse_enum_default_member tests/test_main.py::test_main_dataclass_base_class tests/test_main.py::test_main_jsonschema_combine_any_of_object tests/test_main.py::test_main_jsonschema_has_default_value tests/test_main.py::test_main_with_bad_extra_data tests/test_main.py::test_main_openapi_nullable tests/test_main.py::test_main_use_generic_container_types_py36 tests/test_main.py::test_main_self_reference tests/test_main.py::test_main_modular_reuse_model tests/test_main.py::test_simple_json_snake_case_field tests/test_main.py::test_main_with_strip_default_none tests/test_main.py::test_main_nested_json_pointer tests/test_main.py::test_main_openapi_content_in_parameters tests/test_main.py::test_main_modular_filename tests/test_main.py::test_main_openapi_oas_response_reference tests/test_main.py::test_main_openapi_const tests/test_main.py::test_main_openapi_override_required_all_of_field tests/test_main.py::test_main_use_union_operator tests/test_main.py::test_main_jsonschema_complex_any_of tests/test_main.py::test_main_external_files_in_directory tests/test_main.py::test_main_with_snake_case_field tests/test_main.py::test_space_and_special_characters_json tests/test_main.py::test_main_circular_reference tests/test_main.py::test_main_inheritance_forward_ref_keep_model_order tests/test_main.py::test_main_json_reuse_model tests/test_main.py::test_main_jsonschema_special_enum_special_field_name_prefix_keep_private tests/test_main.py::test_main_openapi_nullable_strict_nullable tests/test_main.py::test_pyproject_not_found tests/test_main.py::test_main_jsonschema_multiple_files tests/test_main.py::test_main_jsonschema_field_extras_field_extra_keys tests/test_main.py::test_main_collapse_root_models tests/test_main.py::test_main_complicated_enum_default_member tests/test_main.py::test_main_jsonschema_items_boolean tests/test_main.py::test_main_jsonschema tests/test_main.py::test_main_root_model_with_additional_properties_literal tests/test_main.py::test_main_subclass_enum tests/test_main.py::test_main_generate_from_directory tests/test_main.py::test_main_disable_warnings_config tests/test_main.py::test_main_invalid_model_name_converted tests/test_main_kr.py::test_main_modular_filename tests/test_main_kr.py::test_main_modular_no_file tests/test_main_kr.py::test_target_python_version tests/test_main_kr.py::test_main_use_schema_description tests/test_main_kr.py::test_main_use_field_description tests/test_main_kr.py::test_main_base_class tests/test_main_kr.py::test_main_modular tests/test_main_kr.py::test_main