Using cfv with Existing Tools

If your project already uses prettier, taplo, or yamlfmt for formatting, cfv reads those configs automatically. No setup required.

cfv check .

This works out of the box because cfv recognizes the config files those tools use and applies the relevant settings when formatting. You get the same formatting behavior without running multiple tools.

What cfv reads

.prettierrc

Applies to JSON, JSONC, and YAML files.

Prettier option	cfv option	Notes
tabWidth	Indent width
useTabs	Spaces or tabs
printWidth	Max line width
endOfLine	Line ending	lf and crlf map; auto and cr are ignored
trailingComma	Trailing commas	JSONC only; all, es5, or none
singleQuote	Quote style	YAML only

Supported config files (checked in this order, first match wins):

1. .prettierrc (JSON tried first, then YAML)
2. .prettierrc.json
3. .prettierrc.yaml / .prettierrc.yml
4. .prettierrc.toml

cfv walks up from each file's directory and uses the nearest match. Unlike .editorconfig, prettier configs are not merged across directory levels.

Not supported: .prettierrc.js, .prettierrc.cjs, .prettierrc.mjs, prettier.config.* (require JS evaluation), "prettier" key in package.json, and the overrides array.

taplo.toml

Applies to TOML files only.

Taplo option	cfv option
formatting.indent_string	Indent width, or tabs
formatting.column_width	Max line width
formatting.trailing_newline	Trailing newline
formatting.reorder_keys	Sort keys
formatting.crlf	Line ending
formatting.array_trailing_comma	Trailing commas

cfv searches for taplo.toml or .taplo.toml in the current directory and parents. [[rule]] sections and options without a cfv equivalent (align_entries, align_comments, compact_arrays, compact_inline_tables, array_auto_expand, array_auto_collapse) are ignored.

.yamlfmt

Applies to YAML files only. Takes precedence over .prettierrc for YAML when both exist.

yamlfmt option	cfv option
formatter.indent	Indent width
formatter.line_ending	Line ending
formatter.max_line_length	Max line width

cfv searches for .yamlfmt or .yamlfmt.yaml walking up from the working directory. Other yamlfmt options (include_document_start, retain_line_breaks, pad_line_comments) are ignored.

.editorconfig

Applies to all formats as a baseline. Format-specific tool configs take precedence over .editorconfig for the properties they share.

EditorConfig property	cfv option
indent_style	Spaces or tabs
indent_size	Indent width
end_of_line	Line ending
insert_final_newline	Trailing newline

Ignore files

cfv also reads each tool's ignore/exclude mechanism. Files that match are skipped from format checking but still syntax-validated.

Tool	Mechanism	Applies to
prettier	.prettierignore (gitignore syntax)	JSON, JSONC, YAML
taplo	exclude array in taplo.toml	TOML
yamlfmt	exclude list in .yamlfmt + .yamlfmtignore file	YAML

.prettierignore is found by walking up from the search directory (same as prettier's own behavior). Patterns are relative to the directory containing the file.

taplo's exclude uses glob patterns relative to taplo.toml's location.

yamlfmt's exclude and .yamlfmtignore are both relative to .yamlfmt's location. If both specify patterns, they're combined (union).

Ignore files are NOT read when .cfv.toml exists or when --no-config is set. In those cases, use cfv's own mechanisms (--exclude-dirs, --ignore-file, --gitignore) to skip files.

When to add .cfv.toml

You don't need .cfv.toml if your existing tool configs already describe the formatting you want. cfv reads them and does the right thing.

Add .cfv.toml when you want:

• Format settings in one place. Instead of settings split across .prettierrc, taplo.toml, and .editorconfig, put everything in .cfv.toml and remove the others.
• cfv-specific options. Some settings (like indent-sequences for YAML or per-format sort-keys) exist only in .cfv.toml.
• Validation options. Schema maps, exclude directories, and reporter settings go in .cfv.toml.

Once .cfv.toml exists, cfv stops reading .prettierrc, taplo.toml, .yamlfmt, AND their ignore files. It becomes the sole formatting authority. .editorconfig support under .cfv.toml is planned for v3.1.

Handling conflicts

If your project has both .prettierrc and .yamlfmt, there's no conflict. cfv uses .yamlfmt for YAML and .prettierrc for JSON/JSONC. The two never compete for the same format.

A malformed or unreadable config file is skipped. cfv logs a warning and falls back to defaults for that format.

Differences from the original tools

cfv aims to produce identical output to prettier (for JSON/JSONC/YAML) and taplo (for TOML) given the same settings. A small number of edge cases produce different output. See Formatting Differences for the full list.