Structured Outputs
glossary beginner 3 min
Sources verified Dec 27, 2025
Getting AI to return data in predictable, typed formats instead of free-form text.
Simple Definition
Structured Outputs means getting AI to return data in a specific format (JSON, TypeScript objects) that your code can reliably parse, instead of free-form text that might be unpredictable.
Technical Definition
A technique for constraining AI responses to match a predefined schema:
// Instead of parsing: "The user John Doe, age 25, lives in NYC"
// Get: { name: "John Doe", age: 25, city: "NYC" }
const UserSchema = z.object({
name: z.string(),
age: z.number(),
city: z.string()
});
Popular tools:
- Zod (TypeScript/JavaScript)
- Pydantic (Python)
- Instructor (wrapper for both)
- OpenAI's JSON mode / Claude's structured output
Why It Matters
Without structured outputs:
- AI might say "John is 25" or "Age: twenty-five" or "25 years old"
- Parsing is fragile and error-prone
- Edge cases break your code
With structured outputs:
- AI always returns
{ "age": 25 } - Type-safe at compile time
- Schema validation catches errors
- Code is reliable and testable
Key Takeaways
- Structured outputs = AI returns typed data, not free-form text
- Use Zod (TS) or Pydantic (Python) for schema definition
- Enables reliable parsing and type safety
- Schema-first development treats the schema as a contract
Sources
Tempered AI — Forged Through Practice, Not Hype
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