What “Unexpected Token” Actually Means
A message such as Unexpected token } in JSON at position 418 means the parser reached a character that cannot legally appear at that point. The visible token is often the symptom, not the original cause. A missing comma just before the closing brace, for example, can make the brace look guilty.
Start a few characters before the reported position and look for the expected separator. In an object that is usually a comma or colon; in an array it is usually a comma or closing bracket.
Turn Character Positions Into Useful Locations
Minified JSON may contain thousands of characters on one line, so a numeric position is hard to scan. Paste it into a formatter that preserves the original error context or use an editor that can jump to a character offset.
Once the document is formatted, inspect the current object and its parent. An unmatched quote early in a string can make the parser misread many later characters, so repair from the first error and validate again.
Fix one error at a time. Parser messages often change after each repair because the first error prevented the parser from reaching later ones.
Separate Syntax Errors From Schema Errors
A syntax validator answers whether the text is valid JSON. It does not know whether an API expects an email, a UUID, or a number in a particular field.
After the syntax becomes valid, compare the result to an example payload or JSON Schema. This second step catches correctly formatted but semantically invalid data.