JSON Basics: Formatting, Validation and Common Errors
Updated 2 August 2026 · 5 min read
The five JSON mistakes that break APIs, and a clean workflow to validate, clean and minify payloads.
The most common errors
Almost every invalid JSON document has one of these:
- Trailing commas after the last item
- Single quotes instead of double quotes
- Unquoted keys
- Comments (JSON does not allow them)
- Unescaped line breaks inside strings
Format for humans, minify for machines
Pretty-printed JSON is easier to review and diff. Minified JSON is smaller to send. The API-Ready JSON workflow does both: validate → format → clean → minify.