Debugging a 4 MB Minified JSON API Response with Python and jq

A partner's billing webhook delivered a 4 MB single-line JSON file that failed to load with an unhelpful error pointing to line 1, column 48130. The author found the real cause, a missing comma after an event_id value, by using the error's character offset rather than its line number. They then describe a Python script that prints a window of text around the failure point and a stricter parser that rejects duplicate keys and non-standard constants. The approach adds some cost, since the strict hooks slow parsing on large documents, so it is reserved for suspicious deliveries. The article also notes that pretty-printing inflates the file by about 40 percent and suggests jq as a fallback when Python is unavailable.