The Complete Guide to JSON Syntax Errors (With Examples and Fixes)

If you've ever stared at Unexpected token ... in JSON at position ... and had no idea what went wrong, this guide is for you. JSON looks simple — and it is. But its strictness catches developers off guard constantly. Unlike JavaScript objects, JSON has zero tolerance for syntax shortcuts. One wrong character and the entire document fails to parse. Here are the 7 most common JSON syntax errors, why they happen, and how to fix each one. Error 1: Trailing Commas The single most common JSON error. You'll hit this one more than all others combined. Broken: { "name" : "Alice" , "age" : 30 , "role" : "developer" , } The error: SyntaxError: Unexpected token } in JSON at position 56 Why it happens: JavaScript objects and arrays happily accept trailing commas. JSON does not. When you copy an object literal from your code into a .json file or an API request body, that trailing comma comes along for the ride. Fixed: { "name" : "Alice" , "age" : 30 , "role" : "developer" } JavaScript detection and