Fix “Unexpected end of JSON input” (no upload)

What the error actually means

This error means the parser reached the end of the text while still expecting more JSON. In practice, the JSON is truncated or incomplete.

It’s common when copying from logs, cutting off a response, or accidentally deleting the last closing bracket or quote.

• Array not closed: missing ] at the end.
• Object not closed: missing } at the end.
• String not closed: missing the closing ".

How to locate the missing part quickly

Start by checking the last 5–20 characters. If the tail ends with a comma, colon, or an opening bracket, that’s a strong signal of truncation.

Then validate a smaller snippet: remove the last few lines and see if the error shifts. The goal is to find the first point where the structure becomes incomplete.

• Look at the very end first (most truncations happen there).
• Search for unmatched {/} and [/] counts.
• If you copied from a UI, check if it collapsed long fields or truncated output.

Validate locally before converting

If you’re converting JSON to CSV, you need strict JSON first. Validate locally, fix the structure, and only then export.

A local validator is safer for sensitive payloads because there is no upload step, even for large or private datasets.

Trust note: All processing happens locally in your browser. Files are never uploaded.

FAQ

Can this error be caused by trailing commas? Not usually. Trailing commas typically trigger an “Unexpected token” error earlier, while this one points to incomplete input.

How do I avoid it next time? Copy via “raw” view when possible, or download the response to avoid UI truncation and hidden ellipses.

const text = input.trim();
const value = JSON.parse(text);
console.log(Array.isArray(value) ? 'array' : typeof value);