API version

Address Validation

Search Suggestions

Customer Tax Registration

Upsert customer tax registration

Customers

Get customers Create customer Get customer by external id Get customer by id Update customer Get transactions by customer id Create transaction by customer id

Exemptions

Get exemptions Create exemption Get exemption by id Get attachments for exemption Upload exemption certificate

Filings

Get filings Get filings by registration id Get filing by id Approve filing

Nexus

Get nexus for org Get physical nexus Create physical nexus Get physical nexus categories Update physical nexus Delete physical nexus Get nexus details for id

Products

Get products Create product Get product categories Get product by id Update product

Registrations

Get registrations Create registration Get jurisdiction specific fields List registration jurisdictions Get registration by id Update registration Upload registration attachment Deregister registration Get oss countries for registration

Tax Estimation

Transactions

Get transactions Create transaction Archive transaction by id Get transaction by external id Get transactions by filing id Create credit note by transaction id Update credit note by transaction id Get transaction by id Update transaction Set transaction tax only

API reference / v1

Finish connecting a freshbooks business isn't part of v1

This endpoint is only in the Tenanted API. v1 has no equivalent.

View in 2026-07-21 v1 reference home

Finish connecting a freshbooks business (2026-07-21) | Kintsugi API Reference