@llmignore/parser

Parse and match .llmignore, .cursorignore, .aiignore, and 10+ other AI ignore file formats. Zero dependencies.

Built by rival.tips — the AI model comparison platform.

Install

npm install @llmignore/parser

Usage

Parse an ignore file

import { parse } from "@llmignore/parser";

const result = parse(`
# Secrets
.env
.env.*
**/*.pem

# Re-include example config
!.env.example
`);

console.log(result.patternCount); // 4
console.log(result.negationCount); // 1
console.log(result.patterns);
// [
//   { pattern: ".env", isNegation: false, isDirectoryOnly: false, isAnchored: false, source: 3 },
//   { pattern: ".env.*", isNegation: false, isDirectoryOnly: false, isAnchored: false, source: 4 },
//   { pattern: "**/*.pem", isNegation: false, isDirectoryOnly: false, isAnchored: false, source: 5 },
//   { pattern: ".env.example", isNegation: true, isDirectoryOnly: false, isAnchored: false, source: 8 },
// ]

Match file paths

import { parse, match } from "@llmignore/parser";

const { patterns } = parse(`
*.log
!important.log
node_modules/
`);

match(patterns, "debug.log");           // true  (excluded)
match(patterns, "important.log");       // false (re-included by negation)
match(patterns, "src/app.ts");          // false (not matched)
match(patterns, "node_modules", true);  // true  (directory-only pattern, isDirectory=true)
match(patterns, "node_modules");        // false (directory-only pattern, but isDirectory defaults to false)

Find all matching patterns

import { parse, matchAll } from "@llmignore/parser";

const { patterns } = parse(`
*.log
!important.log
`);

const hits = matchAll(patterns, "important.log");
// Returns both patterns that matched:
// [
//   { pattern: "*.log", isNegation: false, ... },
//   { pattern: "important.log", isNegation: true, ... }
// ]

List supported formats

import { FORMATS, getFormat } from "@llmignore/parser";

console.log(FORMATS.length); // 13

const cursor = getFormat("cursorignore");
// {
//   id: "cursorignore",
//   filename: ".cursorignore",
//   tool: "Cursor",
//   description: "Blocks files from all AI features in Cursor",
//   official: true,
//   supportsNegation: true,
//   supportsCascading: false,
//   docsUrl: "https://cursor.com/docs/context/ignore-files"
// }

Supported Formats

| Format | File | Tool | Official | |--------|------|------|----------| | llmignore | .llmignore | Universal | Yes | | cursorignore | .cursorignore | Cursor | Yes | | aiignore | .aiignore | JetBrains | Yes | | aiexclude | .aiexclude | Google Gemini | Yes | | claudeignore | .claudeignore | Claude Code | No | | codeiumignore | .codeiumignore | Windsurf | Yes | | geminiignore | .geminiignore | Gemini CLI | Yes | | aiderignore | .aiderignore | Aider | Yes | | clineignore | .clineignore | Cline | Yes | | rooignore | .rooignore | Roo Code | Yes | | augmentignore | .augmentignore | Augment | Yes | | copilotignore | .copilotignore | GitHub Copilot | No | | repomixignore | .repomixignore | Repomix | Yes |

API

parse(content: string): ParsedIgnoreFile

Parses raw ignore file content into structured pattern objects.

Returns a ParsedIgnoreFile with:

• patterns — Array of Pattern objects
• patternCount — Total number of patterns
• negationCount — Number of negation (!) patterns

match(patterns: Pattern[], filePath: string, isDirectory?: boolean): boolean

Checks if a file path is excluded by the given patterns. Uses gitignore's "last matching rule wins" semantics. Negation patterns re-include previously excluded paths.

matchAll(patterns: Pattern[], filePath: string, isDirectory?: boolean): Pattern[]

Returns all patterns that match the given path (without applying last-match-wins). Useful for debugging or building UIs that show why a file was excluded.

FORMATS: Format[]

Array of all 13 supported AI ignore file format definitions.

getFormat(id: string): Format | undefined

Look up a format by its id (e.g., "cursorignore").

Pattern Syntax

The parser follows .gitignore conventions:

| Syntax | Meaning | |--------|---------| | # | Comment line | | !pattern | Negation (re-include) | | * | Match anything except / | | ** | Match zero or more directories | | ? | Match one character except / | | [abc] | Character class | | pattern/ | Match directories only | | /pattern | Anchored to root | | dir/file | Implicitly anchored |

Links

• .llmignore spec & builder
• Spec repository
• rival.tips — AI model comparison

License

MIT