Configuration Overlay & Merge
About Config Overlay / Merge
Config Overlay / Merge applies environment-specific settings to a base JSON, YAML or TOML mapping and shows exactly which paths were added, changed, deleted or replaced.
How it works
Deep object overlay
Mappings merge recursively, override-only keys are added and scalar or incompatible values replace the base. The output uses the base file's format when automatic detection is selected.
Array and deletion policy
Arrays can be replaced, concatenated or concatenated with semantic duplicates removed. Optional null-as-delete behavior makes JSON and YAML overlays practical for removing inherited keys.
Value-free change report
The preview lists escaped object paths, action names and before/after types without embedding configuration values. Copy and download return the clean merged configuration only.
Frequently asked questions
Can the base and override use different formats?
Yes in Auto mode. Each input is detected independently and the merged result is serialized in the base format.
Are comments preserved?
No. Overlay merging works on resolved data models, so comments and source formatting are not retained.
Does the report reveal changed secrets?
No. It includes paths and type transitions only, never old or new values.
Sources & last verified
The behaviour of this tool and the claims on this page were checked against the specifications below on . Everything runs in your browser, so the output you see is exactly what the engine produced.
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