JSON mode forces AI models to return valid, parseable JSON - eliminating formatting errors and making output directly usable by downstream systems. These 238 models support structured JSON output, essential for production API integrations, data extraction pipelines, and content generation workflows.
Models with both JSON mode and function calling are ideal for building automated workflows, AI agents, and production integrations where structured I/O is critical.
| # | Model | Score |
|---|---|---|
| 1 | GPT-5.4 ProOpenAI | 94 |
| 2 | GPT-5.4OpenAI | 94 |
| 3 | GPT-5.4 MiniOpenAI | 93 |
| 4 | GPT-5.2 ProOpenAI | 93 |
| 5 | GPT-5.2OpenAI | 93 |
| 6 | Claude Opus 4.6Anthropic | 92 |
| 7 | GPT-5 ProOpenAI | 92 |
| 8 | o3 Deep ResearchOpenAI | 92 |
| 9 | Claude Opus 4.5Anthropic | 90 |
| 10 | Gemini 3 Pro PreviewGoogle | 90 |
| 11 | GPT-5OpenAI | 90 |
| 12 | Gemini 3 Flash PreviewGoogle | 89 |
| 13 | Claude Sonnet 4.6Anthropic | 89 |
| 14 | Claude Sonnet 4.5Anthropic | 89 |
| 15 | o3 ProOpenAI | 88 |
| 16 | Grok 4.1 FastxAI | 87 |
| 17 | Grok 4xAI | 86 |
| 18 | Grok 4.20 BetaxAI | 86 |
| 19 | o3OpenAI | 86 |
| 20 | Gemini 3.1 Pro PreviewGoogle | 86 |
JSON mode constrains the model's output to always produce syntactically valid JSON. Unlike asking the model to "respond in JSON" via prompting - which can fail with extra text or malformed brackets - JSON mode enforces structure at the decoding level, giving you 100% parseable responses every time.
Production systems need reliable, machine-readable output. JSON mode lets you pipe model responses directly into APIs, databases, and downstream services without brittle regex parsing or error-prone string extraction. This is the foundation of reliable AI-powered backends.
Extract structured entities from unstructured text - names, dates, addresses, product details, sentiment labels - and receive them as clean JSON objects. Combined with a JSON schema, you can enforce exact field names and types for consistent, predictable extraction at scale.
Generate blog posts, product descriptions, or social media content where each piece is returned as a structured JSON object with title, body, tags, and metadata fields. This enables automated content pipelines where every output slots directly into your CMS or publishing system.
Without JSON mode, models may wrap output in markdown code fences, add preamble text, or produce subtly invalid JSON. In production, these edge cases cause silent failures. JSON mode removes the entire class of formatting bugs.
Skip writing and maintaining output validation logic, retry mechanisms for malformed responses, and regex-based extractors. JSON mode lets you trust the output format and focus on business logic instead.
Models with both JSON mode and function calling (197 models on this page) are the best choice for AI agents and automation. JSON mode handles output structure, function calling handles actions - together they enable fully automated, reliable AI workflows.
Structured JSON output means the AI model guarantees its response follows a specific JSON schema. This is essential for building reliable applications that parse AI responses programmatically, without worrying about formatting errors.
GPT-4o, Claude 3.5, Gemini 2.0, and most modern LLMs support JSON output mode. Some offer strict schema validation (guaranteed conformance), while others provide best-effort JSON formatting.
JSON mode ensures the response is valid JSON. Structured outputs go further — they guarantee the JSON matches a specific schema you define, including required fields, types, and nested structures.