2026-08-07

Common JSON errors and how to fix them

Fix trailing commas, single quotes, unquoted keys, and other JSON parse errors. Validate JSON locally with Jigglify.

JSON parse errors are usually small mistakes that are hard to see in a minified string. Below are the issues that show up most often - and how to fix them - then validate locally so you know the payload is clean.

Trailing commas

A comma after the last property or array element is valid in modern JavaScript, but invalid in JSON. Delete the extra comma before { or ].

Single quotes

JSON strings must use double quotes. Replace 'hello' with "hello".

Unquoted keys

{ name: "Ada" } is not JSON. Quote the key: { "name": "Ada" }.

Comments

Standard JSON does not support // or block comments. Remove them, or keep a separate documented format (JSONC) and convert before sending to APIs that expect strict JSON.

How to validate quickly

Open JSON Validate mode.
Paste the payload and run Validate.
If it fails, fix the syntax (often a trailing comma), then Format for a readable view.

Validate JSON free in your browser - catch parse errors without uploading the file.
Open the free JSON tool →