Elixir Mix Build & Deps Folders (_build & deps)

Bottom Line: It is 100% safe to delete _build and deps folders in Elixir and Phoenix projects. Running mix clean or wiping these folders will not delete your .ex source files.

What are the _build and deps Folders?

Located inside Elixir and Phoenix Framework projects, _build and deps are created by the Mix build tool.

• deps/: Contains local copies of Hex packages and Git dependencies downloaded by Mix.
• _build/: Stores compiled Erlang BEAM bytecode (.beam), protocol consolidations, and static assets for dev, test, and prod environments.

If you work on multiple Elixir projects, _build artifacts and deps repositories can accumulate gigabytes of obsolete build clutter.

Can You Delete _build and deps?

✅ Yes, it is completely safe to delete.

• Zero code loss: Your Elixir code, Phoenix templates, mix.exs, and mix.lock remain untouched.
• Auto-rebuilt: Running mix deps.get and mix compile will re-fetch dependencies and compile a fresh _build folder.

How to Safely Clean Up Elixir Build Folders

Method 1: Using Built-in Mix Commands (Recommended)

To clean compiled BEAM build files for the current environment:

mix clean

To clean build files across all environments (dev, test, prod):

mix clean --all

Method 2: Manual Directory Wipe

To force a complete dependency and build reset:

# macOS / Linux
rm -rf _build deps

# Windows (PowerShell)
Remove-Item -Recurse -Force _build, deps

Related Guides

• Learn about deleting node_modules folders.
• How to clean up Python venv folders.
• Check if you can clean git folders.