Free Online JSON Diff Tool

How to Compare JSON Online

This online JSON diff tool compares two JSON objects side by side and highlights what was added, removed, or changed after normalization. It works well for API responses, configuration files, translation dictionaries, package.json files, feature flags, request payloads, and any structured JSON content you need to review quickly.

Why normalized JSON diff is easier to read

Raw JSON often contains formatting noise such as indentation differences, key order changes, or minified content. This tool parses each side first, validates the JSON, then formats it into a stable readable structure before generating the diff preview. With key sorting enabled, object key order stops distracting from the actual data changes.

Useful JSON diff scenarios

  • Compare API responses between two environments.
  • Review request payload changes before calling an endpoint.
  • Compare config files such as feature flags, app settings, or deployment variables.
  • Check translation JSON, i18n dictionaries, and locale file updates.
  • Review package.json, manifest files, test fixtures, or mock data changes.

Format, validate, and compare in one place

You can paste the original JSON on the left and the updated JSON on the right. Each side shows whether the JSON is valid, how many keys it contains, and how many normalized lines it becomes. If the pasted JSON is valid, you can format one side or both sides into a consistent pretty-printed version before exporting the diff report.

Local browser processing

JSON parsing, formatting, comparison, and report export all run locally in your browser. Your API payloads, config snippets, and internal data are not uploaded to a server. This makes the tool suitable for debugging, code review, release checks, and operational copy changes on a trusted device.

Export JSON diff results

After both sides are valid, you can copy the JSON diff report or download it as a TXT file. The report includes the current normalization settings together with the diff output and both normalized JSON blocks, which is useful for review notes and change records.