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Overview

Structured outputs enable you to enforce specific response formats from Perplexity’s models, ensuring consistent, machine-readable data that can be directly integrated into your applications without manual parsing. We currently support two types of structured outputs: JSON Schema and Regex. LLM responses will work to match the specified format, except for the following cases:
  • The output exceeds max_tokens
Enabling the structured outputs can be done by adding a response_format field in the request: JSON Schema
  • response_format: { type: "json_schema", json_schema: {"schema": object} } .
  • The schema should be a valid JSON schema object.
Regex (only available for sonar right now)
  • response_format: { type: "regex", regex: {"regex": str} } .
  • The regex is a regular expression string.
Improve Schema Compliance: Give the LLM some hints about the output format in your prompts to improve adherence to the structured format.For example, include phrases like “Please return the data as a JSON object with the following structure…” or “Extract the information and format it as specified in the schema.”
The first request with a new JSON Schema or Regex expects to incur delay on the first token. Typically, it takes 10 to 30 seconds to prepare the new schema, and may result in timeout errors. Once the schema has been prepared, the subsequent requests will not see such delay.

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Examples

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1. Financial Analysis with JSON Schema

curl -X POST "https://api.perplexity.ai/chat/completions" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "sonar-pro",
    "messages": [
      {
        "role": "user", 
        "content": "Analyze the latest quarterly earnings report for Apple Inc. Extract key financial metrics."
      }
    ],
    "response_format": {
      "type": "json_schema",
      "json_schema": {
        "schema": {
          "type": "object",
          "properties": {
            "company": {"type": "string"},
            "quarter": {"type": "string"},
            "revenue": {"type": "number"},
            "net_income": {"type": "number"},
            "eps": {"type": "number"},
            "revenue_growth_yoy": {"type": "number"},
            "key_highlights": {
              "type": "array",
              "items": {"type": "string"}
            }
          },
          "required": ["company", "quarter", "revenue", "net_income", "eps"]
        }
      }
    }
  }' | jq

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2. Extract Contact Information with Regex

curl -X POST "https://api.perplexity.ai/chat/completions" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "sonar",
    "messages": [
      {
        "role": "user",
        "content": "Find the direct email address for the investor relations contact at Tesla Inc."
      }
    ],
    "response_format": {
      "type": "regex",
      "regex": {
        "regex": "[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,}"
      }
    }
  }' | jq

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Best Practices

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Generating responses in a JSON Format

For Python users, we recommend using the Pydantic library to generate JSON schema. Unsupported JSON Schemas Recursive JSON schema is not supported. As a result of that, unconstrained objects are not supported either. Here’s a few example of unsupported schemas: 
# UNSUPPORTED!

from typing import Any

class UnconstrainedDict(BaseModel):
   unconstrained: dict[str, Any]

class RecursiveJson(BaseModel):
   value: str
   child: list["RecursiveJson"]
Links in JSON Responses: Requesting links as part of a JSON response may not always work reliably and can result in hallucinations or broken links. Models may generate invalid URLs when forced to include links directly in structured outputs.To ensure all links are valid, use the links returned in the citations or search_results fields from the API response. Never count on the model to return valid links directly as part of the JSON response content.

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Generating responses using a regex

Supported Regex
  • Characters: \d, \w, \s , .
  • Character classes: [0-9A-Fa-f] , [^x]
  • Quantifiers: *, ? , +, {3}, {2,4} , {3,}
  • Alternation: |
  • Group: ( ... )
  • Non-capturing group: (?: ... )
Unsupported Regex
  • Contents of group: \1
  • Anchors: ^, $, \b
  • Positive lookahead: (?= ... )
  • Negative lookahead: (?! ... )
  • Positive look-behind: (?<= ... )
  • Negative look-behind: (?<! ... )
  • Recursion: (?R)

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Perplexity’s JSON Schema Implementation

Perplexity’s structured outputs implementation has several key differences compared to other providers:

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Simplified Schema Definition

  • Optional naming: Unlike other providers that require explicit schema names, Perplexity automatically handles schema naming with sensible defaults
  • Flexible strictness: Schema validation is handled automatically without requiring manual strictness configuration
  • Streamlined syntax: You only need to provide the core schema object without additional wrapper fields
Other Providers: 
{
  "response_format": {
    "type": "json_schema",
    "json_schema": {
      "name": "financial_data",
      "strict": true,
      "schema": { /* your schema */ }
    }
  }
}
Perplexity: 
{
  "response_format": {
    "type": "json_schema", 
    "json_schema": {
      "schema": { /* your schema */ }
    }
  }
}

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Enhanced Error Handling

  • Clear error messages: When schemas fail validation, you’ll receive specific, actionable error messages
  • Recursion protection: Built-in safeguards prevent infinite recursion in complex nested schemas
  • Constraint validation: Automatic detection and clear messaging for unsupported features like unconstrained objects

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Schema Compatibility

While Perplexity supports standard JSON Schema syntax, some advanced features may not be available:
  • Recursive schemas are not supported for performance and reliability reasons
  • Unconstrained objects (like dict[str, Any]) are automatically detected and rejected
  • Complex reference patterns may require simplification
This approach prioritizes reliability and performance while maintaining compatibility with most common JSON Schema use cases.

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Structured Outputs for Reasoning Models

When using structured outputs with reasoning models like sonar-reasoning-pro, the response will include a <think> section containing reasoning tokens, immediately followed by the structured output. The response_format parameter does not remove these reasoning tokens from the output, so the final response will need to be parsed manually. Sample Response: 
<think>
I need to provide information about France in a structured JSON format with specific fields: country, capital, population, official_language.

For France:
- Country: France
- Capital: Paris
- Population: About 67 million (as of 2023)
- Official Language: French

Let me format this information as required.
</think>
{"country":"France","capital":"Paris","population":67750000,"official_language":"French"}
For a reusable implementation to extract JSON from reasoning model outputs, see our example utility on GitHub.