Changelog

Bulk relationship writes — PATCH /objects/{object}/records/{id}/relationships/{relationship} now supports updating relationships across multiple records in one request. See relationships.
Campaign recipient unsubscribe status — Recipient objects now expose an unsubscribed_at field so you can see which contacts opted out and when.

Bulk PATCH preserves untouched attributes — PATCH /objects/{object}/records now leaves any field you didn't include in the body unchanged, matching the single-record PATCH behavior. Previously the bulk variant could null missing fields. If you built workarounds for the old behavior, you can drop them. See records.
Get a comment — GET /comments/{id} is now available in the external API for completeness alongside create/update/delete.
Empty enum options — Custom fields with enum/select types now accept an empty option set (useful for fields whose options come from upstream sources). See schema.
Relationship field validation — Tightened request validation on relationship fields; invalid payloads now return 422 with a specific error message instead of silently failing.

Custom objects — Create your own object types beyond person, company, deal, and meeting. POST /schemas/objects
Schema management — Create and update fields programmatically. POST /schemas/{entity}/properties
Bulk delete — Delete multiple records in one request. DELETE /objects/{object}/records

Comments API — Add, update, and delete comments on any record. POST /comments
Recording API — Enable/disable meeting recording and access artifacts.
CSV export — Export list rows as CSV. POST /objects/{object}/lists/{list}/rows/csv

Relationships — Link and unlink records across object types. PATCH /objects/{object}/records/{id}/relationships/{relationship}
Filter operators — New operators: Is empty, Is not empty, Greater than, Less than, One of
Pagination — Offset-based pagination for all list endpoints with meta.total_records