I'm building a workflow tool and need an AI API that outputs JSON

If you need an AI API that reliably outputs JSON, the best option is usually to use a model/API with structured output support rather than just asking the model to “return JSON.”

Good options

• OpenAI API: supports JSON mode / structured outputs and is a strong fit for workflow tools.
• Anthropic Claude: can produce JSON, but structured guarantees depend on the integration pattern.
• Google Gemini: also supports structured output in some setups.

What to look for

For workflow automation, you typically want:

• Valid JSON every time
• Schema enforcement if possible
• Support for nested objects, arrays, enums
• Ability to map output directly into your tool’s steps

Recommended approach

Use an API feature that lets you define a JSON schema, for example:

• required fields
• data types
• allowed values
• no extra keys

That’s much safer than prompting alone.

Example shape

{
  "task": "send_email",
  "recipient": "user@example.com",
  "subject": "Welcome",
  "body": "Thanks for signing up."
}

If you want, I can help you with either:

1. a specific API recommendation, or
2. a sample request/response JSON schema for your workflow tool.