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JSON Checker

Paste JSON to validate it, fix syntax issues faster, and optionally format, minify, or normalize (sort keys). Everything runs locally—no uploads.

Category: Developer · URL: /tools/json-checker.html
Input JSONTip: Ctrl/⌘ + Enter = Format
Strict JSON rules: double quotes for keys/strings, no comments, no trailing commas.
OutputReadonly
Related tools:
Privacy: runs locally in your browser. No uploads, no tracking scripts.

How to use

Use this tool to verify and clean JSON before you ship it into an API, config, or file.

  1. Paste your JSON into the input box.
  2. Click Validate to check if it parses (errors include line/column).
  3. Click Format to pretty-print or Minify to compact.
  4. Use Sort + Minify to normalize key order for stable diffs.
  5. Click Copy Output to copy the result.
Keywords this page targets (natural cluster): json checker, json validator, validate json online, json syntax checker, json formatter, pretty print json, json minifier, minify json online, json linter, find json error line column, sort json keys, normalize json, compact json, check json array, check json object, json parser online, fix invalid json, json beautifier, json to single line, json canonicalize
Secondary intents covered: Validate whether pasted text is valid JSON, Locate the error position with line/column and nearby snippet, Pretty-print JSON with configurable indentation, Minify JSON to a single line for APIs or storage, Sort object keys recursively to create stable diffs, Copy the cleaned output to clipboard quickly, Load sample JSON to test parsing behavior, Confirm the top-level type (object/array) and basic stats

FAQ

Does this JSON checker upload my data?

No. Validation and formatting run locally in your browser.

Does it support comments or trailing commas?

No—this is strict JSON. Remove comments and trailing commas to validate successfully.

How do I find where the JSON error prevents parsing?

When parsing fails, the tool shows the error plus a best-effort position with line/column and a small snippet.

What is the difference between Format and Minify?

Format adds indentation and line breaks for readability; Minify removes extra whitespace to produce compact JSON.

What does “Sort + Minify” do?

It sorts object keys recursively, then outputs compact JSON—useful for stable diffs and consistent snapshots.

Can JSON have duplicate keys?

It can appear in text, but parsers typically keep the last value for a duplicated key; avoid duplicates to prevent surprises.

Will this preserve number precision?

JSON numbers are parsed as JavaScript Numbers; very large integers may lose precision when parsed and re-stringified.