> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.merge.dev/merge-unified/supplemental-data/field-mapping/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.merge.dev/_mcp/server.

# Field Mapping

> Build once. Connect to every API, tool, and LLM. Ship products and agents to production without owning the integration stack.

## Docs

- [Field Mapping](https://docs.merge.dev/merge-unified/supplemental-data/field-mapping/overview.md): How Field Mapping works — create target fields on Common Models, then map third-party custom fields to them at the integration or Linked Account level.
- [Quickstart video](https://docs.merge.dev/merge-unified/supplemental-data/field-mapping/quickstart-video.md): Video walkthrough of Field Mapping setup — creating target fields, configuring mappings, and accessing mapped data.
- [Target fields](https://docs.merge.dev/merge-unified/supplemental-data/field-mapping/target-fields.md): How to create and manage target fields — the custom fields you define on Common Models that third-party data gets mapped into.
- [Mapping across an integration](https://docs.merge.dev/merge-unified/supplemental-data/field-mapping/mapping-across-an-integration.md): How to create integration-wide Field Mappings that apply to all Linked Accounts using a given integration (e.g., all Salesforce accounts).
- [Mapping for a Linked Account](https://docs.merge.dev/merge-unified/supplemental-data/field-mapping/mapping-for-a-linked-account.md): How to create Field Mappings scoped to a single Linked Account, for cases where field names or structures differ between customers.
- [Advanced mapping](https://docs.merge.dev/merge-unified/supplemental-data/field-mapping/advanced-mapping.md): How to use JSONata expressions to transform, filter, or reformat third-party field values before they land on your target fields.
- [AI data transformations](https://docs.merge.dev/merge-unified/supplemental-data/field-mapping/ai-data-transformations.md): How to use Merge's AI assistant to auto-generate JSONata transformation expressions for Field Mapping, instead of writing them manually.
- [Access mapped data](https://docs.merge.dev/merge-unified/supplemental-data/field-mapping/access-mapped-data.md): How to read mapped field values from the API and view mapping configurations in the Merge Dashboard.