Deep merge two JSON objects — the second object overwrites and extends the first. Useful for combining configuration files, API responses, or default settings with overrides.
Paste two JSON objects separated by a blank line. The second object will be merged into the first. Nested objects are recursively merged.
JavaScript spread ({...a, ...b}) only does shallow merge. Our deep merge recursively combines nested objects while preserving existing keys from the first object.
Arrays from the second object replace arrays in the first. They are not merged element-by-element. For array concatenation, modify the output manually.