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Free JSON Diff Checker Online

Paste two JSON objects to see exactly what changed — added keys in green, removed in red, changed values in yellow. Deep diff, free, no signup.

JSON is compared server-side. Input is processed and immediately discarded — nothing is stored.
Original JSON
Modified JSON
Paste JSON into both panes and click Compare.
Tip: Ctrl+Enter / Cmd+Enter triggers Compare from anywhere in the panes.

About JSON Diff Checker

JSON Diff Checker is a free server-side tool that compares two JSON objects and highlights exactly what changed. Paste the original and modified JSON into the two panes and click Compare. Added keys appear in green, removed keys in red, and changed values in yellow. Unchanged lines are hidden by default to keep the output clean — toggle "Hide unchanged lines" off to see the full structure.

Two display modes: side-by-side shows the original and modified JSON in parallel columns, making it easy to spot structural differences at a glance. Unified mode shows a single column with + and - prefixes, similar to the output of git diff. The Copy and Download buttons export the current diff view as plain text.

Common use cases

  • Compare API responses before and after a code change to confirm the output is correct.
  • Verify that a JSON config migration preserved all expected keys and changed only the intended values.
  • Debug a regression by comparing the JSON output from two different build versions.
  • Check that a JSON serialization library round-trips data without silent field drops or type coercions.
  • Review infrastructure-as-code diffs: compare a Terraform state file before and after a terraform apply.

Frequently asked questions

What is a JSON diff checker?

A JSON diff checker compares two JSON objects and highlights the differences: keys present in the second object but not the first (added, shown in green), keys present in the first but not the second (removed, shown in red), and keys present in both but with different values (changed, shown in yellow). Unchanged keys are shown without highlighting or hidden entirely.

Does it handle nested JSON?

Yes. The comparison is recursive — it walks into nested objects and arrays at every level. A changed value deep inside a nested structure is highlighted at its exact level, not as a change to the entire parent object.

What does "Ignore key order" do?

When enabled, {"a":1,"b":2} and {"b":2,"a":1} are treated as identical because they contain the same key-value pairs regardless of order. When disabled (the default), key ordering is considered significant and a key appearing in a different position shows as changed.

What is the input size limit?

Each pane accepts up to 1 MB of JSON. Inputs over 1 MB return an error. For very large JSON files, consider splitting the comparison by extracting specific sub-objects and comparing those sections individually.

Is my JSON data sent to a server?

Yes — the comparison runs server-side to support accurate recursive diffing of arbitrarily deep structures. Your JSON is processed in memory and discarded immediately after the response is sent. Nothing is written to disk or retained between requests.

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