Quick start#

Install the native TomlSmith CLI from crates.io.

Install the CLI#

cargo install tomlsmith-cli --locked

The crate declares Rust 1.85 as its minimum supported version. rustup can install and select a compatible toolchain.

Check, format, parse#

tomlsmith check Cargo.toml
tomlsmith fmt Cargo.toml
tomlsmith fmt --check Cargo.toml
tomlsmith parse Cargo.toml

• check validates the document and prints diagnostics with exact source locations.
• fmt formats the document in place; fmt --check only reports whether formatting would change anything, which is what you want in CI.
• parse emits the selected version, validity, and diagnostics as JSON.

Choose the TOML version#

TOML 1.1 is the default. Select TOML 1.0 explicitly when the file must stay compatible with 1.0-only consumers such as Cargo:

tomlsmith --toml-version 1.0 check Cargo.toml

Both versions are strict modes: a TOML 1.1 construct in a 1.0 run produces a diagnostic. The LSP and VS Code extension instead default to 1.0 for ecosystem compatibility; the version policy lists every surface.

Standard input and automation#

Every command accepts a file path or - for standard input, and diagnostics can be emitted as machine-readable JSON for tools and automation.

echo 'title = "TomlSmith"' | tomlsmith check -

List all commands and options:

tomlsmith --help

Browser workbench#

The playground checks and formats TOML in the browser. You can switch between TOML 1.0 and 1.1, inspect diagnostics and tokens, and preview formatting without changing the source.