diff --git a/.gitignore b/.gitignore
index 7e8820fd6..b44ff01f4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -45,6 +45,9 @@ cmake-build-*/
 .kdev?/
 *.kdev?
 
+# clangd LSP files
+**.cache/clangd
+
 # File-based project format:
 *.iws
 
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6366a5ce6..2edb41be6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,6 +3,14 @@
 cmake_minimum_required(VERSION 3.20.0)
 project(ImpactX VERSION 23.06)
 
+# generate compile_commands.json
+if(${CMAKE_GENERATOR} STREQUAL "Unix Makefiles" OR ${CMAKE_GENERATOR} STREQUAL
+                                                   "Ninja")
+  if(CMAKE_SOURCE_DIR STREQUAL PROJECT_SOURCE_DIR)
+      set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+  endif()
+endif()
+
 include(${ImpactX_SOURCE_DIR}/cmake/ImpactXFunctions.cmake)
 
 # In-source tree builds are messy and can screw up the build system.