JSON Schema Diff Tool
Compare two JSON Schemas side by side. Detect added, removed, and changed properties, types, and constraints for API versioning.
How ZeroData protects your privacy
- ✓ No Uploads: Processing happens entirely via client-side JavaScript.
- ✓ No Storage: We do not have a database. We physically cannot save your data.
- ✓ No Tracking: We don't log what you process or track your inputs.
- ✓ Verifiable: Check your DevTools Network tab. You will see 0 outbound requests.
Why JSON Schema Diffing Matters for API Development
APIs evolve. Fields get added, types change, validation rules tighten. Without a systematic way to track these changes, you risk deploying breaking changes that crash client applications. JSON Schema diffing provides a structured, automated way to answer the question: "What changed between version 1 and version 2 of this API?"
This tool performs a deep, recursive comparison of two JSON Schemas and produces a clear, color-coded report of every structural change. It's designed for the real-world workflow of reviewing API PRs, planning migrations, and writing changelogs.
Understanding Breaking vs Non-Breaking Changes
Not all schema changes are equal. Non-breaking changes are safe to deploy without updating clients: adding optional properties, relaxing constraints (increasing maxLength, widening enum values), or adding new formats. Breaking changes will cause existing clients to fail: removing properties, changing types (integer → string), adding required fields, or restricting enum values.
This tool flags both types — the 'Removed' and 'Changed' indicators help you quickly identify breaking changes that need careful rollout or versioning.
Deep Recursive Schema Comparison
Real-world schemas have nested objects, arrays of objects, and deeply nested validation rules. This tool walks the entire schema tree recursively, comparing properties at every level, checking items schemas for arrays, and tracking the full dotted path (e.g., user.address.city) for each change.
Related JSON Schema Tools
Validate your schemas with the JSON Schema Validator, generate schemas from sample data with the JSON to JSON Schema Converter, or convert schemas to TypeScript interfaces using the JSON Schema to TypeScript Generator. For general text comparison, use the Diff Checker.
100% Client-Side — Your Schemas Stay Private
API schemas often contain proprietary business logic and internal data structures. This tool processes everything in your browser — no data is transmitted, stored, or logged. The diff engine runs entirely in JavaScript memory, and schemas are discarded when you close the tab.
How to Use the JSON Schema Diff Tool
- Paste your old JSON Schema into the 'Schema A' panel on the left.
- Paste your new JSON Schema into the 'Schema B' panel on the right.
- Click 'Compare Schemas' to generate the diff report.
- Review the color-coded results: green for added, red for removed, yellow for changed.
- Click 'Export as Markdown' to copy the diff as a markdown table for documentation.
Common Use Cases
- Reviewing API schema changes before deploying a new version to production.
- Detecting breaking changes in OpenAPI / Swagger schema definitions during code review.
- Generating changelog entries for API versioning documentation.
- Validating that a schema migration preserves backward compatibility with existing clients.
- Comparing auto-generated schemas from different versions of a TypeScript or database model.
Frequently Asked Questions
What is a JSON Schema diff and why do I need it?
A JSON Schema diff compares two versions of a JSON Schema to identify structural changes — added or removed properties, type changes, updated constraints (minLength, enum values, required fields), and modified validation rules. This is critical for API versioning: it tells you exactly what changed between v1 and v2 of your API contract, helping you assess backward compatibility and plan client-side updates.
What types of changes does this tool detect?
The tool detects: added properties (in new schema but not old), removed properties (in old but not new), type changes (e.g., integer to string), constraint changes (minLength, maxLength, minimum, maximum, pattern, enum values), required field changes (added or removed from the required array), $ref changes, additionalProperties changes, and format changes. It handles nested objects recursively.
Can this tool detect breaking changes?
Yes. The following changes are generally considered breaking: removing a property, changing a property type, adding a new required field, narrowing enum values, or setting additionalProperties from true to false. The diff report highlights these as 'Removed' or 'Changed', helping you identify backward-incompatible modifications.
Does this tool support nested schemas and arrays?
Yes. The diff engine recursively walks into nested objects (type: object with properties) and array items schemas (items). Changes at any depth are reported with their full dotted path (e.g., address.city.type), making it easy to trace exactly where the change occurred.
Is my schema data safe?
Yes. This tool runs 100% in your browser. No schema data is sent to any server. The comparison runs entirely in JavaScript within your browser. You can verify this using the Network tab in your browser's Developer Tools.
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