Compare JSON by keys and values, not line position

Direct answer

How does semantic JSON comparison differ from a text diff?

Diff Anything parses JSON before comparing it, so formatting and property order do not create meaningless line changes. Lists of records are matched by an id field automatically, numbers compare by value, and applying a change keeps the target file's comments and layout. Pro profiles can retain ignored paths, keyed or unordered array behavior, case rules, numeric tolerances, and review state.

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Formatting noise

Key order and spacing are not changes.

A line diff of two JSON files often shows hundreds of changes after a serializer sorts keys differently or changes the indentation. Diff Anything parses both documents first and compares the values, so the same data written in a different order or layout produces no differences.

When a value changes type, for example from the string "1" to the number 1, it is reported as a type change instead of an ordinary value change. Numbers are compared by value, so 1, 1.0 and 1e0 are equal, and numbers too large or precise for ordinary arithmetic keep their exact digits. To treat small differences as equal, set a Numeric tolerance above 0.

Files with // or /* */ comments or trailing commas are accepted. If a document repeats a key, the last value is used and a warning names the duplicate. When only one file repeats the key, that warning counts as a difference.

Arrays

Match array items by a key instead of by position.

Arrays are where most JSON diffs go wrong. When every item of an array is an object with a unique id, _id, uuid or key field, Diff Anything pairs the items by that field automatically. Locations then read like $.users[id=2].role, an inserted record is reported as added instead of shifting every record after it, and a list whose records only moved shows one note, such as "Array members at $.users were reordered".

Other arrays are compared by index. If both hold the same items in a different order, the result reports one reorder instead of a change at every position. For lists of records identified by another field, add an Array keys rule such as $.orders = orderNumber, and locations read like $.orders[orderNumber=1042].total. When every object shares a unique field such as name, Recommended rules offers it as a one-click suggestion, for example "Compare $.servers by name".

If a key is missing from an item or repeated, an Array keys rule cannot be used and the comparison falls back to array indexes with a warning. For lists where order does not matter, such as tags, add the path to Unordered array paths.

Semantic rules

Hide fields you expect to change.

Open Semantic rules to tell the comparison what to leave out. Ignore paths removes volatile fields such as $.metadata.generatedAt. Ignore case at paths compares string values at those paths without letter case. Numeric tolerance treats numbers within a fixed absolute difference as equal.

A path is either exact or ends in .* to cover everything below it. Recommended rules looks at the current result and suggests array keys, ignored order, case rules, volatile fields such as generatedAt, and numeric tolerances, so you can add a rule with one click. Rules are part of the free plan; saving them in a profile for the next run needs Pro.

• Ignore paths
• Unordered array paths
• Ignore case at paths
• Array keys (one path = key per line)
• Numeric tolerance

Apply and CLI

Copy a change into the other file.

Select a difference and use Right → left or Left → right to copy it into the other file. Only that value is written: the target keeps its comments, trailing commas, indentation and line endings.

The command line compares JSON on the free plan with the default rules, and --exit-code returns 1 when the files differ. Semantic rules set in the app are not read by the command line.

Best for

Where this workflow fits.

• Configuration files whose key order changes
• API responses with volatile fields or unordered collections
• Sensitive JSON that should remain on the local machine

No accounts, cloud comparison service, analytics, or telemetry.

Relevant capabilities

What Diff Anything brings to the job.

Practical workflow

From setup to a reviewed result.

1. Open both JSON files

   Choose files or paste JSON. Auto opens them in JSON mode in the Tree view; the Semantic tab lists every difference.

2. Remove known noise

   Add Ignore paths for timestamps and request ids, or accept a suggestion from Recommended rules.

3. Key your arrays

   Records with an id, _id, uuid or key field are paired automatically. For other records, add an Array keys rule or accept a suggestion such as Compare $.servers by name.

4. Review and copy changes

   Filter by Added, Removed, Changed or Types, mark items reviewed, and copy the values you want across.

Useful in practice

Direct answers

Questions about JSON diff tool.

Go deeper

Choose sources, understand automatic detection, and select the engine that answers the question you are actually asking.

Related guides

Understand the workflow from another angle.