post https://e-networkId.adzerk.net/udb/networkId/custom
With this you can tie Custom Properties to a specific UserKey using key/value pairs. For instance, {"Key":"Value"} could be {"favoriteColor": "blue"}. Note that each call to set custom properties will replace any existing custom properties.
The max size of a custom data object in a UserDB record is 8 KB.
We recommend using either
camelCaseorsnake_casecustom property keys as these work well with Zerkel. Howeverkebab-caseshould be avoided. Also, symbol prefixes (like$,%,:, etc.) should not be used.