A simple JSON parser specifically designed to handle malformed JSON output from Large Language Models (LLMs) like GPT, Claude, and others.
- Markdown Block Extraction: Extracts JSON from ```json code blocks and inline
code - Trailing Content Removal: Removes explanatory text after valid JSON structures
- Quote Fixing: Fixes unescaped quotes inside JSON strings
- Missing Comma Detection: Adds missing commas between array elements and object properties
- Single-line JSON support for compact LLM outputs like
{"a": 1 "b": 2}and[1 2 3] - Multi-line JSON support for formatted outputs
- Single-line JSON support for compact LLM outputs like
- Zero Dependencies: Pure TypeScript/JavaScript implementation
- Comprehensive Testing: 86+ tests covering real LLM output patterns
- TypeScript Support: Full type definitions included
- Configurable: Multiple parsing modes and options
- Error Recovery: Graceful handling of malformed input
npm install ai-json-fixerimport { LLMJSONParser } from 'ai-json-fixer'; const parser = new LLMJSONParser(); // Parse JSON from LLM output with markdown const llmOutput = `Here's the data you requested: \`\`\`json { "users": [ {"name": "Alice", "age": 30}, {"name": "Bob", "age": 25} ], "total": 2 } \`\`\` This JSON contains the user information.`; const result = parser.parse(llmOutput); console.log(result); // Output: { users: [...], total: 2 }const input = `\`\`\`json\n{"key": "value"}\n\`\`\``; const result = parser.parse(input); // { key: "value" }const input = '{"message": "He said "hello" to me"}'; const result = parser.parse(input); // { message: 'He said "hello" to me' }const input = '{"status": "ok"} The request was successful.'; const result = parser.parse(input); // { status: "ok" }Multi-line JSON:
const input = `{ "name": "John" "age": 30 }`; const result = parser.parse(input); // { name: "John", age: 30 }Single-line JSON:
// Objects const input1 = '{"a": 1 "b": 2 "c": 3}'; const result1 = parser.parse(input1); // { a: 1, b: 2, c: 3 } // Arrays const input2 = '[1 2 3 4 5]'; const result2 = parser.parse(input2); // [1, 2, 3, 4, 5] // Complex structures const input3 = '[{"id": 1} {"id": 2}]'; const result3 = parser.parse(input3); // [{ id: 1 }, { id: 2 }]Parse JSON input with automatic fixing. Returns parsed object or null if parsing fails.
Parse with detailed results including applied fixes and confidence score.
interface ParseOptions { mode?: 'strict' | 'standard' | 'aggressive'; stripMarkdown?: boolean; trimTrailing?: boolean; fixQuotes?: boolean; addMissingCommas?: boolean; trackFixes?: boolean; throwOnError?: boolean; maxFixAttempts?: number; }interface ParseResult<T> { data: T | null; fixes?: Fix[]; confidence?: number; warnings?: string[]; }# Install dependencies npm install # Run tests npm test # Build npm run build # Run examples npx tsx examples/basic-usage.tsMIT