TOML is a config format designed by GitHub co-founder Tom Preston-Werner in 2013 as a more readable alternative to YAML and INI. Its appeal is unambiguous syntax — TOML files always parse the same way regardless of indentation. Used by Cargo (Rust), pyproject.toml (Python packaging), pnpm-workspace, Hugo, Netlify, and many others. v1.0.0 spec finalized in 2021.
How to open
Any text editor. Most modern IDEs ship TOML syntax highlighting; VS Code's Even Better TOML extension adds validation.