Debug an API JSON response — without pasting it into random websites
API responses carry tokens, emails, and production records. Format and validate them locally in your browser, where nothing is ever uploaded.
Why local debugging matters
The fastest way to debug a JSON response is to paste it into an online formatter. The problem: many of those tools send your payload to their backend, where it can sit in logs and analytics. A response copied from a staging or production environment often contains auth tokens, customer records, or internal IDs — exactly the data you do not want leaking.
The safe loop is local-first: the JSON Formatter parses and pretty-prints entirely in your browser. You get the same formatted output and the same syntax-error positions, and the payload never leaves your device.
The workflow, step by step
- 1
Copy the exact response body — DevTools → Network → Response, or the output of your HTTP client.
- 2
Paste it into the JSON Formatter. Formatting and validation run instantly as you type.
- 3
Read the first reported syntax error and its position — trailing commas, quotes, and stray HTML are the usual suspects.
- 4
Compare the parsed shape with what your client expects, then copy the clean JSON or the minimal failing fragment.
Debug your response now
Open the formatter, paste the payload, and see the problem in seconds. Local-only, free, and no signup.
Open JSON FormatterFrequently asked questions
How do I debug an API JSON response?
Copy the raw response body from DevTools (Network tab → Response) or your HTTP client, paste it into the JSON Formatter, and read the validation output. The formatter pretty-prints the payload and points at the exact position of syntax errors, so you can see whether the problem is your client or the server.
Is it safe to paste an API response that contains real data?
On most online tools, no — the payload is sent to their server and can be logged. The Simply Tools JSON Formatter works the opposite way: parsing happens entirely in your browser with JavaScript, so responses containing tokens, emails, or production records never leave your device.
Why does my API return invalid JSON?
The usual culprits: an HTML error page returned with a 200 status (check whether the body starts with <!), a proxy injecting a login redirect, trailing commas, single quotes instead of double quotes, unescaped newlines inside strings, or a UTF-8 BOM at the start of the body. The validator pinpoints the first character position that breaks parsing.
The HTTP status is 200 — why is the body still an error?
Some APIs return status 200 with an error object in the body, and misconfigured servers return an HTML login or error page with 200. Always check the Content-Type header (application/json vs text/html) and the shape of the body. The formatter shows immediately whether you received JSON at all.