JSON Merge Patch tester
Apply a JSON Merge Patch to a document and inspect the result before updating an API.
Up to 1,000,000 characters, 50,000 values and 64 nesting levels per document. UTF-8 file imports are limited to 1 MB. Processing runs in a local worker with a 10-second timeout and a bounded work budget. Duplicate keys and numbers that cannot be preserved safely are rejected. Paste the original JSON document. Use the second editor for the merge patch or target document. Up to 1,000,000 characters. Review the settings before running.
Your result
How to use JSON Merge Patch tester
- Paste the original JSON document and the merge patch, or open two UTF-8 JSON files.
- Apply the patch and inspect the result. No API request is sent.
- Copy the result or download the complete JSON and report.
Useful next steps
Null removes an object member
In a merge patch, a null-valued object member removes that member. To store an explicit null, use another update format. A non-object patch, including a root null or an array, replaces the whole target.
Arrays are replaced in full
JSON Merge Patch does not update individual array positions. It also works on data rather than formatting, so whitespace and key order can change. The report retains the original document and patch text.