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Programming Foundations
Phase 0Module 9 of 14

JSON

AI systems constantly exchange structured data. JSON is readable, lightweight, and works in every programming language.

JSON is a standardized form every department fills out the same way — whether you're in Python, JavaScript, or Go.

Visual Workflows

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Overview

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Key Takeaways

  • 1.JSON is the universal data format for AI — every LLM request, response, tool schema, and config file uses it.
  • 2.Objects {key: value}, arrays, strings, numbers, booleans, null.
  • 3.Keys need double quotes.
  • 4.Python uses json.dumps and json.loads.

Real Example

Scenario

You need the LLM to call a weather function with a city name.

What you would do

Define the tool schema in JSON, send it with the chat request, and the LLM returns JSON with the function name and arguments.

Practice Task

Run: python -c "import json; d={'role':'user','content':'hi'}; print(json.dumps(d))" then parse it back with json.loads. Confirm the output uses double quotes on keys.

Commands

Commands to Remember

  • python -c "import json; print(json.dumps({'a':1}))" # convert Python dict to JSON string
  • python -c "import json; print(json.loads('{\"a\":1}'))" # parse JSON string to Python dict

Cheat Sheet

Quick recap

quick ref
  • Universal format for all AI APIs — objects, arrays, strings, numbers
  • Keys must use double quotes — no trailing commas or single quotes
  • Used for LLM requests, chat messages, tool schemas, and configs
  • Python: json.dumps (object → string) · json.loads (string → object)
  • Validate structure with Pydantic or JSON Schema
  • LLMs may wrap JSON in markdown fences — strip before parsing

Common Mistakes

  • Not validating JSON from LLM outputs
  • Single quotes in JSON (invalid)
  • Forgetting to strip markdown fences