JSON

JSON is a text format for data that looks almost like Python lists and dictionaries, and the json module converts between the two.

Last updated: 30 Sep, 2026 · Python 3.14

To use a model's answer rather than only display it, you ask the model for JSON. Files, from Reading and writing files, often hold JSON too.

Syntax:

json.loads(text)     # JSON text -> Python value
json.dumps(value)    # Python value -> JSON text
json.load(f)         # from an open file
json.dump(value, f)  # to an open file

Reading JSON text with json.loads

import json

answer = '{"category": "billing", "priority": 4}'
data = json.loads(answer)

print(type(answer))
print(type(data))
print(data["priority"] + 1)

<class 'str'>
<class 'dict'>
5

answer is a string that looks like a dictionary. json.loads, load from a string, reads it and builds the real dictionary, so data["priority"] is a number you can add to.

Writing JSON text with json.dumps

result = {"id": 3, "category": "billing", "reply": None, "urgent": True}
print(json.dumps(result))
print(json.dumps(result, indent=2))

{"id": 3, "category": "billing", "reply": null, "urgent": true}
{
  "id": 3,
  "category": "billing",
  "reply": null,
  "urgent": true
}

json.dumps goes the other way. Look at what changed: JSON writes None as null and True as true, and always uses double quotes. indent=2 spreads it over lines for people to read.

Loading the tickets file

The five tickets the rest of the course uses live in a file:

[
  {
    "id": 1,
    "customer": "Asha",
    "text": "I was charged twice for one order"
  },
  {
    "id": 2,
    "customer": "Ben",
    "text": "My parcel has not arrived"
  },
  {
    "id": 3,
    "customer": "Chen",
    "text": "Can I get a refund for the blue mug?"
  },
  {
    "id": 4,
    "customer": "Dara",
    "text": "How do I change my password?"
  },
  {
    "id": 5,
    "customer": "Eli",
    "text": "The parcel arrived but the box was crushed"
  }
]

Five dictionaries in a list, each with an id, a customer and the text they wrote. Reading the file gives that list back.

with open("tickets.json") as f:
    tickets = json.load(f)

print(len(tickets))
for ticket in tickets:
    print(ticket["id"], ticket["text"])

5
1 I was charged twice for one order
2 My parcel has not arrived
3 Can I get a refund for the blue mug?
4 How do I change my password?
5 The parcel arrived but the box was crushed

json.load, without the s, reads from an open file. The file becomes a list of dictionaries, the shape from Lists of dictionaries.

Saving a summary with json.dump

counts = {"tickets": len(tickets), "customers": [t["customer"] for t in tickets]}

with open("summary.json", "w") as f:
    json.dump(counts, f, indent=2)

with open("summary.json") as f:
    print(f.read())

{
  "tickets": 5,
  "customers": [
    "Asha",
    "Ben",
    "Chen",
    "Dara",
    "Eli"
  ]
}

json.dump writes to an open file, and reading the file back shows the JSON it wrote.

JSON vs Python spelling

Where JSON shows up in AI code

• Asking a model to answer in JSON, then reading the answer with json.loads.
• The body of almost every web API request and response.
• Saving results, settings and test cases to files.

Related

• Previous: Reading and writing files
• Next: Stand-in model
• Reference: The json module in the Python docs