#263 · Developer Tool

YAML Merge Key Resolver

Expand common YAML merge keys into explicit mappings so inherited configuration is visible during review. The resolver reads block-style anchor mappings, finds <<: *alias entries, copies missing keys at the merge location, and keeps local keys as overrides. Its output removes the merge line while retaining the surrounding YAML layout. A summary shows which anchors were used and how many properties were inserted, making configuration diffs less opaque.

Developer Input

Block-style YAML
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How to use this developer tool

  1. Paste or upload the block-style yaml you want to inspect.
  2. Run Resolve Merge Keys, or press Ctrl/Cmd + Enter.
  3. Read the summary, diagnostics, and reported counts before using the output.
  4. Copy the result or download it in the shown format.

What this developer tool does

The resolver captures mapping blocks attached to named anchors and replaces single-alias merge keys with copied key-value lines at the target indentation. Keys already present in the target mapping win.

Only direct block mappings and the standard single alias form <<: *name are expanded. Local entries are collected before insertion, so their order does not change override behavior.

Use the result as a review aid. Confirm advanced merge arrays, nested anchor graphs, flow mappings, and tagged values with your application YAML parser.

Example

The Sample button loads a representative block-style yaml. Running it produces the same kind of expanded yaml shown in the result panel, including counts that are calculated from the supplied text rather than fixed examples.

defaults: &defaults
  retries: 3
  timeout: 30
service:
  <<: *defaults
  timeout: 45
  enabled: true

Use cases

  • Review configuration changes before committing them.
  • Diagnose format-specific problems in CI or deployment inputs.
  • Create a copy-ready result for documentation or another developer tool.
  • Check generated files without exposing project data to a remote service.

Tips for reliable output

  • Start with the smallest input that reproduces a problem.
  • Keep a copy of the original before replacing configuration files.
  • Read warnings and limitations, even when the main result succeeds.
  • Validate the output again with the parser used by your application.
  • Use UTF-8 when saving downloaded text.

Processing details

The scanner preserves original scalar text and comments on copied lines. It changes only recognized merge-key lines and does not coerce values through JSON.

Merge arrays such as <<: [*base, *extra], aliases that point to sequences, and anchors declared in flow style are rejected instead of partially expanded.

Frequently asked questions

Does YAML Merge Key Resolver upload my input?

No. Processing runs in your browser, and the page does not send the supplied text to an API.

What input should I use with YAML Merge Key Resolver?

Paste plain YAML text; line endings and Unicode content are accepted.

Will the output cover every edge of the format?

Merge arrays such as <<: [*base, *extra], aliases that point to sequences, and anchors declared in flow style are rejected instead of partially expanded.

What happens when the input is invalid?

The run stops and the error area identifies the first problem the tool can locate. No partial result is presented as complete.

Can I save the result?

Yes. Copy the output, download the primary result, or use the structured JSON or CSV download when those buttons appear.

Tool details

CategoryData & Format Tools
InputBlock-style YAML
Primary outputExpanded YAML
Runs locallyYes
Data & Format ToolsBrowse JSON, YAML, TOML, XML, and structured-data utilities.Open category →