Find common JSON errors with a small example

Reduce the failing input and fix syntax before investigating an application-level problem.

Start with quotes and commas

A common mistake is writing JavaScript object syntax as JSON. An unquoted key or single-quoted string may work in JavaScript source but fails in JSON. A comma belongs between items, never after the final item.

Use the small valid example below as a starting point. Add fields one by one until the failing section is isolated. Keep confidential data out of support messages.

{"name":"Ada","count":3,"enabled":false,"note":null}

Escape characters inside strings

A quotation mark inside a string needs a backslash. A literal line break inside a string is invalid; represent it with the escape sequence \n. Backslashes themselves need escaping.

Do not replace all quotes automatically: that can corrupt text values. Check the exact context around an error and make the smallest necessary correction.

{"note":"Say \"hello\"","path":"C:\\data","lines":"one\ntwo"}

Syntax and data meaning are different

A value such as "3" is a string, while 3 is a number. Both are valid JSON, but they are not interchangeable for every API. null, an empty string and an absent key also have different meanings.

The formatter validates syntax only. If parsing succeeds but an application rejects the file, inspect the application’s schema or error response. Dates and URLs are strings and need their own checks.

Use controlled error tests

Try a missing closing bracket, a trailing comma and an unquoted key. Each should produce an error without a download or a success result. Then restore the valid example and confirm both generated files parse.

The processor runs in a worker and can be cancelled. Inputs over 10 MB are rejected, and processing is stopped after 30 seconds. These are resource limits, not evidence about your data’s correctness.