diff --git a/fortitude_linter/fortitude_launcher.py b/fortitude_linter/fortitude_launcher.py
new file mode 100644
index 00000000..f8a5f0d8
--- /dev/null
+++ b/fortitude_linter/fortitude_launcher.py
@@ -0,0 +1,103 @@
+#!/usr/bin/env python3
+##############################################################################
+# (c) Crown copyright Met Office. All rights reserved.
+# The file LICENCE, distributed with this code, contains details of the terms
+# under which the code may be used.
+##############################################################################
+
+"""
+Launch fortitude on list of directories. Run on all and print outputs.
+Fail if any style changes required.
+"""
+
+import sys
+import subprocess
+import argparse
+from pathlib import Path
+
+
+def launch_fortitude(
+    config_path: Path, app_path: Path
+) -> subprocess.CompletedProcess[str]:
+    """
+    Launch fortitude as a subprocess command and check the output
+    """
+
+    command: list[str] = [
+        "fortitude",
+        "--config-file",
+        str(config_path),
+        "check",
+        str(app_path),
+    ]
+    result = subprocess.run(command, capture_output=True, text=True)
+
+    print(result.stdout)
+    return result
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(
+        description="Run fortitude on all applications. If "
+        "application/fortitude.toml exists use that file, otherwise "
+        "use one in rose-stem/app/check_fortitude_linter/file. "
+        "Print output, raise error if any changes required."
+    )
+    parser.add_argument("source", help="The top level of lfric_apps directory.")
+    args = parser.parse_args()
+
+    source_path: Path = Path(args.source)
+
+    failed_apps: dict[str, str] = {}
+
+    for top_dir_path in source_path.iterdir():
+        # e.g. applications,science,interfaces
+        if not top_dir_path.is_dir():  # don't try to loop over files
+            continue
+        for app_path in top_dir_path.iterdir():
+            # e.g. adjoint_tests, adjoint, coupled_interface
+            if not app_path.is_dir():
+                continue
+            app_name: str = app_path.name
+            print(f"Running on {app_name}\n")
+            config_path: Path = app_path / "fortitude.toml"
+            if not config_path.exists():
+                print(
+                    "Using universal config (toml) file."
+                    " (Some apps use their own config file.)"
+                )
+                config_path: Path = (
+                    source_path
+                    / "rose-stem"
+                    / "app"
+                    / "check_fortitude_linter"
+                    / "file"
+                    / "fortitude.toml"
+                )
+            result: subprocess.CompletedProcess[str] = launch_fortitude(
+                config_path, app_path
+            )
+            if result.returncode:
+                # prints the app run on if there are errors of any kind
+                print(f"Checking: {app_name} \n", file=sys.stderr)
+                if not result.stderr:
+                    # prints if no other/config errors are found
+                    print("Found lint errors:", file=sys.stderr)
+                    # prints the lint errors
+                    print(result.stdout, file=sys.stderr)
+                if result.stderr:
+                    # prints if there are other/config errors
+                    print("Found non-lint errors: \n", file=sys.stderr)
+                    # prints the other/config errors
+                    print(result.stderr, "\n\n\n", file=sys.stderr)
+                failed_apps[app_name] = result.stderr
+
+    if failed_apps:
+        error_message: str = ""
+        print(
+            "\n\n\nSummary: Fortitude found errors in the following repositories:\n",
+            file=sys.stderr,
+        )
+        for failed in failed_apps:
+            error_message += f"{failed}\n"
+        sys.exit(error_message)