Is the JSON lesson free?

The interactive JSON lesson is part of Pro (₹299/month). The first 5 lessons of the track are free — no account or card needed.

How long does the JSON lesson take?

About 5 minutes end-to-end. It's a hands-on lesson — you read a paragraph, edit the code, and run it in the same tab.

Do I need to install Python to try the JSON lesson?

No install required. PyRun runs real CPython in your browser via Pyodide (Python compiled to WebAssembly). Works on Chrome, Firefox, Safari, and Edge — desktop or mobile.

What level is the JSON lesson?

Intermediate level. Best after finishing the Beginner track (syntax, control flow, functions, data types).

JSON

Intermediate
5 min
Fundamentals
intermediate · data
Try it

Lesson 22 of 43

In this track

You’ll be able to

Parse JSON strings into Python objects with json.loads
Serialize Python objects to JSON with json.dumps
Handle nested JSON data returned from APIs
Deal with dates, sets, and other non-JSON-native types

Why this matters

Every REST API, config file, and log aggregator (Datadog, ELK) speaks JSON. Python's json module can't serialize datetime, Decimal, or set out of the box — a TypeError that hits every new backend engineer. orjson is 5-10x faster for hot paths.

Common pitfalls

Serializing datetime or Decimal directly — pass a custom default= handler or use pydantic/orjson.
Using json.loads on untrusted large payloads without a size cap — memory-exhaustion DoS vector.
Round-tripping floats and expecting exact equality — JSON has no Decimal; keep money as strings.

Intermediate · 6 minModules & ImportsHow Python finds code. import, from, as.Intermediate · 9 minRegular ExpressionsPattern matching for text — find, extract, validate.Intermediate · 7 minContext Managers (`with`)Acquire and release resources cleanly. The `with` block, demystified.

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You’ll be able to

Parse JSON strings into Python objects with json.loads
Serialize Python objects to JSON with json.dumps
Handle nested JSON data returned from APIs
Deal with dates, sets, and other non-JSON-native types

Why this matters

Common pitfalls

Serializing datetime or Decimal directly — pass a custom default= handler or use pydantic/orjson.
Using json.loads on untrusted large payloads without a size cap — memory-exhaustion DoS vector.
Round-tripping floats and expecting exact equality — JSON has no Decimal; keep money as strings.

You’ll be able to

Why this matters

Common pitfalls

Related lessons

You’ll be able to

Why this matters

Common pitfalls

Related lessons