Merge YAML and config files
About YAML / Config Merge
This YAML merge tool deep-merges a base file with an override and shows the merged result next to a report of every path it changed. It also merges JSON and TOML configs, and in Auto mode the two files can even use different formats.
Use it to see what a staging or production override really does to your base config, to combine Helm or Compose values files, or to check a layered settings file before you deploy it.
Runs in your browser. Nothing is uploaded.
How it works
Recursive map merge
Mappings merge at every level. Keys that exist only in the override are added, and keys on both sides are merged or resolved by the policy you pick. In Auto mode the output uses the base file's format.
Which side wins
With Override wins, a value in the override replaces the base value, the usual layered config behavior. Base wins keeps the base value on conflicts but still adds keys the base does not have.
Array policy
Arrays can take the override (replace), keep the base, concatenate both, or concatenate with duplicates removed. Unique compares objects by content, with their keys sorted.
Null as delete
With Null deletes keys on, setting a key to null in the override removes it from the result. Turn it off to keep null as a value. TOML has no null, so a TOML result cannot contain one.
Change report without values
The preview lists each changed path as a JSON Pointer with the action and the before and after types, such as change /service/port. It never shows configuration values, so the report is safe to share. Copy and Download return only the merged file.
Frequently asked questions
How do I merge two YAML files?
Paste the base file on top and the override below. The merged YAML updates as you type, with a report of added, changed and deleted paths above it.
Can the base and override use different formats?
Yes, in Auto mode. Each input is detected on its own, and the result is written in the base format.
What counts as a conflict?
Both files set the same path to different scalars, different arrays or values of a different type. Matching values and keys found on only one side are not conflicts.
Are comments preserved?
No. The merge works on parsed data and writes a new document, so comments and source formatting are lost.
Does the report reveal changed secrets?
No. It lists paths and type changes only. Old and new values are never shown.
Sources & last verified
We checked this tool's behavior and the claims on this page against the specifications below on . The tool runs in your browser, so the output you see is exactly what the engine produced.
- YAML 1.2.2 specification
- RFC 8259: The JSON Data Interchange Format
- TOML v1.0.0 specification
- RFC 7386: JSON Merge Patch
Found a wrong result or an outdated claim? Report an error and we will check it again.
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