get https://{youraccountname}.api-us1.com/api/3/customObjects/records//
{
"record": {
"id": "1fba439a-208e-48e6-bd23-f6c97c3e0519",
"externalId": "test-obj-1",
"schemaId": "6449c3f3-b68d-46d1-850b-c8aea998ce1b",
"fields": [
{
"id": "my-number-field",
"value": 100
}
],
"relationships": {
"primary-contact": [
"14"
]
},
"createdTimestamp": "2021-04-16T16:12:22.222685095Z",
"updatedTimestamp": "2021-04-16T16:13:12.022671090Z"
}
}