Data Formats

The FamilySearch API uses the following data formats. Each data format has an associated XML and JSON version.

  • If you make a GET request, specify the data format using the Accept header.
  • If you POST something, specify the media type using the Content-Type header.

Read more about data formats (i.e., "media types") on Wikipedia.


The GEDCOM X data formats define the core data formats for genealogical data.


The FamilySearch data formats provide extensions to the GEDCOM X data formats and are specific to the FamilySearch developer platform.


The Atom data formats are used to provide lists (i.e., "feeds") of data. These feeds are used in ordered result sets, such as search results and change history.

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