Best Practices for Working with JSON

Working with JSON seems simple—just key/value pairs, right? However, as applications scale, sloppy JSON practices can lead to performance bottlenecks, security vulnerabilities, and maintenance nightmares. Here are the 5 core best practices for professional JSON development.

1. CamelCase vs. Snake_case

Consistency is key.
- JavaScript/JSON standard is camelCase (firstName, createdAt).
- Python/Database standard is often snake_case (first_name, created_at).
Rule: When building a public API, stick to camelCase. It aligns with the client-side JavaScript that will likely consume your API. If your backend is Python, convert keys at the API boundary (Serializer layer).

2. ISO 8601 for Dates

JSON has no date type. Never send dates as timestamps (milliseconds) or custom formats like "01/02/2026". Is that January 2nd or February 1st?
Rule: Always use UTC ISO 8601 strings: "2026-02-18T22:00:00Z". Every language has a built-in parser for this format, and the Z explicitly indicates Coordinated Universal Time (UTC), preventing timezone confusion.

3. Flat is Better than Nested

Deeply nested JSON objects increase complexity and parsing time.
Bad:
{"user": {"profile": {"address": {"city": "NY"}}}}
Good:
{"userId": 123, "city": "NY"}
Rule: Keep your structure as flat as reasonably possible. It makes the data easier to query and reduces the risk of undefined errors when accessing deep properties (data.user?.profile?.address?.city).

4. Handling Large Integers

In JavaScript, Number.MAX_SAFE_INTEGER is 2^53 - 1. Many database IDs (Snowflake IDs, MongoDB ObjectIDs) exceed this.
Rule: If a number is an ID or a 64-bit integer, serialize it as a string. {"id": "9823471239847129"}. This prevents browsers from rounding the last digits and corrupting your data identifiers.

5. Security: JSON Hijacking and Script Injection

Never store JSON directly in a <script> tag without sanitization.
var data = <?php echo $json; ?>;
If the JSON contains </script>, it can break out of the tag and execute XSS attacks.
Rule: Always escape user input within JSON. Better yet, load JSON via AJAX/Fetch rather than embedding it in the HTML source.