DEVELOPER WORKSPACE
Fix JSON syntax errors without uploading your payload
A formatter can make a valid API response readable. It cannot decide whether that response has the right fields for your application. Use syntax validation first, then check the shape and values against your API contract.
Open the private JSON workspace
Start with the smallest failing value
Paste a short representative object into the workspace and choose Validate. Fix one error at a time. If a large payload is failing, reduce it to the relevant object while retaining the surrounding braces. Test a copy; keep your original response available so a formatting operation cannot replace your only source.
Load a local file safely
Choose a UTF-8 JSON file up to 2 MB, or paste your payload. Loading only fills the workspace: choose Format, Minify or Validate to inspect it. If you start editing while a file is loading, your newer edits win. File contents stay in the browser frame and are not part of anonymous action measurements.
Common JSON repairs
JSON object names and string values use double quotes. A comma separates entries, but a final comma before a closing brace or bracket is invalid. Comments are not JSON syntax. Use the actual boolean true rather than the string "true" when your API expects a boolean. The formatter reports syntax errors; it does not silently repair them.
| Input | Problem | Repair |
|---|---|---|
| {"count":2,} | Trailing comma | {"count":2} |
| {'name':'Ada'} | Single-quoted strings | {"name":"Ada"} |
| {name:1} | Unquoted object name | {"name":1} |
| {"ready":True} | Incorrect boolean spelling | {"ready":true} |
Protect large identifiers
The browser tool rejects unquoted integers outside JavaScript’s safe-integer range, numeric overflow and nonzero values that underflow to zero. Keep exact identifiers as quoted strings: for example, "9007199254740993". Decimal fractions still use binary floating point, so this is not an exact-decimal accounting tool. Duplicate names remain ambiguous: this browser parser retains the last value; it does not diagnose duplicates.
{
"request_id": "9007199254740993",
"ready": true,
"items": [{"sku": "A-17", "quantity": 2}]
}Choose format, minify or validate
Format uses indentation to help you review nesting. Minify removes presentation whitespace; it is not compression or encryption. Validate checks syntax without producing a downloadable reformatted file. After changing your input, run the chosen action again. Keep secrets out of shared screenshots and links even though the tool processes the payload locally.
When a batch workflow helps
For one response, the browser workspace is enough. For a folder of files, a local batch process can report failures separately and write outputs to a new directory. The prepared offline JSON kit rejects duplicate keys and unsupported numeric ranges, preserves integer precision in Python, and refuses to overwrite existing outputs. Decimal fractions still use binary floating point; it is not an exact-decimal accounting tool. Its checkout availability is shown on the product page.
Reproduce this example
Formatting keeps the quoted orderId exact; items remains an array and paid remains false.
Load API response with a quoted large identifier
Download api-response.json — synthetic data you can save or reference. The diagnostic samples contain no real addresses, credentials or hosted streams. Scenario CSVs document inputs; the calculators do not import CSV.
Common questions
Does valid JSON mean my API request is correct?
No. A syntactically valid value can have missing fields, wrong types or values your API rejects. Validate against the API contract separately.
Why do I get a trailing-comma error?
Remove the comma directly before the closing } or ]. Keep commas between adjacent members or array values.
Does Engine1 upload my JSON?
The product workspace parses JSON in an isolated browser frame. Anonymous action names are measured by the parent page; the payload itself is not included in those events.
Try it with your own scenario
Open the private JSON workspace
The tool is free to use. Product inputs stay in the local browser workspace. Provider links, where present, are separate from the calculation.
References and scope
Updated 2026-09-24. Examples are illustrative calculations, not measured customer outcomes. Provider prices and terms must be checked at purchase time.