Common JSON Validation Mistakes Developers Make
JSON powers modern APIs, web applications, mobile apps, and cloud services.
Yet many developers still lose valuable debugging time because of simple validation mistakes.
The most common issues include:
Missing Commas
A single missing comma can break an entire payload.
Trailing Commas
Unlike JavaScript objects, JSON does not allow trailing commas.
Invalid Quotes
JSON requires double quotes for keys and string values.
Incorrect:
'name': 'John'
Correct:
"name": "John"
Inconsistent Data Types
A field expected as a number should not suddenly become a string.
Bad:
{
"age": "25"
}
Better:
{
"age": 25
}
Nested Structure Errors
Large JSON files often contain misplaced brackets that are difficult to detect manually.
Using a formatter and validator before sending data to production can save hours of troubleshooting and prevent API failures.