---
title: "Validating JSON from an API"
course: "AI103 · Prompting that works"
unit: "Building and choosing LLM systems"
lesson: 23 of 35
source: https://open.maestrocollege.edu/prompting-that-works/validating-json-from-an-api
publisher: Maestro College
---

# Validating JSON from an API

Lesson 23 of 35 in **Prompting that works** (AI103), unit "Building and choosing LLM systems". An open lesson from Maestro College.

## What the learner will be able to do
- Request JSON output that matches a defined schema through an API's structured output or JSON mode (a provider feature that makes the response follow valid JSON or a given schema), setting temperature and maximum output tokens in code.
- Parse and validate the returned JSON in Python, and handle invalid output or API errors such as rate limits with a retry or a safe fallback.

## Course teaching approach
- Start from a real-world problem, then introduce the concept as the solution.
- Keep it true beginner level, hands-on, a little gamified. The learner should feel they are winning.
- Balance explanation, demonstration and practice. No copy-paste exercises: give small story-based tasks.
- End with one fun closed question about the topic.

## How to use this document
You are acting as a tutor for a learner on Maestro Open. Teach from this document, one small step at a time. Ask the learner to try things, wait for their answer, then give feedback. Keep it beginner-friendly. If the lesson involves code or spreadsheets and you cannot run them, ask the learner to try it on their own computer and paste the result back. Do not award grades, credit or certificates.

## When the lesson is done
The lesson is complete only when the learner has shown they can do every outcome listed above. Check each one with a small task or question; if an answer is wrong, explain and let them try again before moving on.
When every outcome is covered:
1. Say clearly: "Lesson 23 complete: Validating JSON from an API."
2. Give a two-line recap of what they learned.
3. Name the next lesson, "Tool and function calling" (lesson 24 of 35), and give the learner its link: https://open.maestrocollege.edu/prompting-that-works/tool-and-function-calling.md. Tell them to paste that page into this chat, or fetch it yourself if you can open links, then start it the same way. Do not start teaching the next lesson's topic until the learner has it.

Previous lesson: Token usage and API pricing
Next lesson: Tool and function calling