GuidesHow to Fix Trailing Commas in JSON
How to Fix Trailing Commas in JSON
Updated 2026-07-23 · SparkJSON
A trailing comma is a comma after the last item in an object or array. JavaScript allows it; JSON does not. SparkJSON reports the exact line and column so you can delete the comma and re-validate instantly.
Why trailing commas happen
They sneak in from JS/TS objects, Python dicts printed casually, or hand-edited configs. Linters for JS often allow trailing commas even though JSON.stringify never emits them.
Fix workflow
Paste into SparkJSON’s validator. Read the error pointing at the comma before `}` or `]`. Remove it, re-run validation, then format for readability.
FAQ
- Are trailing commas ever valid in JSON?
- Not in standard JSON. Some JSON5/JSONC supersets allow them, but interchange JSON for APIs should stay strict.