---
url: https://chartbuddy.io/embed/docs/concepts/defaults.md
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> Docs index: [llms.txt](https://chartbuddy.io/embed/docs/llms.txt)

# Defaults & merging

Partial `chartData` is merged over Chartbuddy defaults when you create or update an Insight.

## Deep-merge keys

These nested objects deep-merge:

* `title`
* `subtitle`
* `legend`
* `axes`
* `canvas`
* `footnote`
* `annotations`

Other top-level keys typically replace.

## Practical tip

Start minimal (`chartType` + `seriesData` + title/subtitle/legend). Add axes or annotations only when you need them, or export a full config from the editor and trim.