**Important:**

Free fields that are added must be present in your API dataset of the endpoint that we provide.

You can find the endpoints in de flow > endpoints

You can't map free fields that are in Meta_data.**How to read / write the free field from the raw data:**If we look at the data below:

{

"object1":{

"key1":"1",

"key2":"value2",

"freeField1":"valueOfFreeField1"

}

}

Here we see an object (called object1) in an object (the two outer curly brackets). If we now want to use the field ‘freeField1’ in our Data Mapping, we can write this as follows:**object1.freeField1**

If we want to use the value of the field ‘freeField1’ in our Data Mapping, we can write this as follows:

**object1.freeField1.value**So, for every object (written with the two curly brackets, { and }), we write this out with dots between the keys.

Now, in a data structure you also have to deal with arrays:

{

"object1":{

"key1":1,

"key2":"value2",

"freeField1":"valueOfFreeField1"

},

"array1":[

{

"key3":3,

"key4":"value4",

"freeField2":"valueOfFreeField2"

}

]

}

If we now want to use the field ‘freeField1’ in our Data Mapping, we can write this as follows:**array1:freeField1**

If we want to use the value of the ‘freeField2’ field in our Data Mapping, we can write this as follows:

**array1:freeField2.value**

So, for every array (written with the two square brackets, [ and ]), we write this out with a colon ( : ) between the keys.

**How to connect the free fields: **Integration > Flow > Data Mapping

if the field is not available in the dropdown (see image below) you can type it in the field. Make sure you describe the field exactly as it comes from your API.

Also note that the middle column is leading, in the above example we see that a gender and birthday field can be applied in our core. if you want to add a field and it is not available in our core (middel column), you can use the following core function for it: contacts.*.customFields.freeStringField0