JSON Schema Diff
Compare two JSON Schemas side-by-side. Shows added, removed and changed fields with semantic meaning.
Compare two JSON Schemas side-by-side. Shows added, removed and changed fields with semantic meaning.
This free JSON Schema Diff from KX Toolkit is part of our all-in-one online toolkit. It runs entirely in your browser, so your data never leaves your device for client-side operations. 100% free, forever - no paywall, no credit card, no trial.
How to use the JSON Schema Diff
- Paste your input - JSON, regex pattern, JWT, URL etc.
- Pick any flags or options the tool supports.
- Click the action button (Format, Test, Decode).
- Copy the result or download it as a file.
What you can do with the JSON Schema Diff
- Format and validate API responses while debugging.
- Test regex patterns against real input before deploying.
- Decode JWTs to inspect claims and expiry.
- Generate UUIDs for migrations, tests and seeders.
Why use KX Toolkit's JSON Schema Diff
- Browser-based: Works on Windows, macOS, Linux, iOS and Android - no install, no extension.
- Privacy-first: Client-side tools never upload your data; server-side tools delete files right after processing.
- Mobile-friendly: Full feature parity on phones and tablets - not a stripped-down view.
- Fast: Optimised for instant feedback. No artificial waiting screens, no email-gated downloads.
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Related Developer Tools
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What kind of schemas can I compare?
Any JSON Schema written as JSON. The tool focuses on the parts that matter for backward-compatibility: the property tree (added, removed, kept), the required list at every level, and the descriptive keywords on each property - type, format, pattern, enum, min/max length, minimum, maximum, items, default, $ref, const, multipleOf. It does not validate schemas against the spec, only diffs them.
How is this different from a plain text diff?
A text diff compares lines and shows what characters changed. This tool understands the schema structure: it knows that reordering properties is not a real change, that promoting a property from optional to required is a breaking change, and that an enum with one extra value is an additive change. The output groups results into Added, Removed, and Changed categories with semantic labels.
When would I use this in real work?
Reviewing an API contract change, comparing request or response schemas between two service versions, auditing whether a deployment changes the database shape, or verifying that a generated schema matches the hand-written one. It pairs well with OpenAPI specs - copy the relevant schema block from each version into the two textareas.
Does it understand $ref or external schemas?
It detects when a $ref string changes and flags it as a Changed attribute, but it does not follow the reference to compare the target schema. If your two schemas use the same $ref pointing to different definitions, the diff will miss those internal differences. For deep comparison, inline the referenced definitions before pasting.
Why is type-changing flagged as breaking?
Changing a property from integer to string forces every consumer to update their parsing and validation. Even if the tool calls it "Changed" rather than "Breaking," any type swap should trigger a major version bump in your API. The same applies to a stricter pattern, a smaller maxLength, or a removed enum value - they reject inputs that previously validated.
Is my data sent anywhere?
No. The diff runs entirely in your browser using JavaScript. Both schemas stay on this page and are never uploaded. Refreshing the page clears them. This makes the tool safe for proprietary or internal API schemas - paste freely, nothing leaves your machine.
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