API changelog
Every change to the Kintsugi API and every release, newest first. Breaking changes carry the mark. Tenanted releases are dated, and you choose one with the Api-Version header.
Changes
2026-10-05
Saves California and Idaho portal access codes with registration credentialsRegistrations
PUT /registrations/{registration_id}/credentials accepts jurisdictionSpecificFields: cdtfaThirdPartyAccessSecurityCode for a California registration and accessCode for an Idaho registration, named as in the credentials reveal response. Only the keys you send change, and leaving the field out or sending null keeps the saved values. The codes are stored encrypted, are never returned by this endpoint, and can be read back with POST /registrations/{registration_id}/credentials/reveal. An unsupported key or a blank value answers 422. A code for a different state than the registration's answers 400, as does a registration that does not yet have its business name, registration type and sales tax id on file.
2026-09-22
Requires a request body to deregister a registrationRegistrations
Deregistering now records when and why the registration closes. POST /v1/registrations/{registration_id}/deregister requires a JSON body with closure_date, reason and final_return_acknowledged, so a request with no body, which succeeded before, is now rejected with 422. The 2026-07-21 release changed the same way, with the fields closureDate, reason and finalReturnAcknowledged.
- Send
closure_date: the date the registration closes with the jurisdiction, as YYYY-MM-DD. Past and future dates are accepted. - Send
reason:FULL_BUSINESS_CLOSUREorCLOSING_NEXUS_IN_STATE. - Send
final_return_acknowledged: true, confirming that a final return is still owed.
Releases
2026-07-21
LatestTenanted APIIntroducing the Tenanted API
A fresh foundation for building on Kintsugi. The Tenanted API is versioned by date, and you choose the release you build against. It speaks one consistent dialect from end to end: clean paths, camelCase fields, exact decimal amounts, and a single error format. And it is built for scale, with one credential reaching every organization it owns.
Compared with v1
| Topic | v1 | 2026-07-21 |
|---|---|---|
| Versioning | The /v1 path prefix | The Api-Version header, dated YYYY-MM-DD. Optional; without it, a request runs against the launch release |
| Paths | /v1/transactions | /transactions |
| Authentication | x-api-key | Api-Key. Endpoints that manage people accept a signed-in session token instead |
| Choosing an organization | x-organization-id, required on almost every request | One credential reaches every organization it owns. Narrow a request with Organization-Id, Connection-Id, or Entity-Id |
| Field names | snake_case | camelCase |
| Money and rates | Decimal strings out, numbers or strings in | Decimal strings at a fixed scale: amounts to 2 places, rates to 9 |
| Timestamps | No single documented format | RFC 3339 in UTC, always ending in Z |
| Errors | Shapes vary by endpoint | One envelope everywhere: code, message, requestId, and errors |
| Portfolio | Not available | Portfolio and Portfolio Reseller endpoints, for partner accounts |
Moving an integration from v1
- Send
Api-Version: 2026-07-21with every request, so your integration stays on this release until you decide to move. - Drop
/v1from your paths. - Send your key as
Api-Key, and replacex-organization-idwithOrganization-Idwherever you target one organization. - Rename fields to camelCase, and read every amount as a decimal string, never a float.
- Branch on the error
code, not the message or the HTTP status, and quoterequestIdwhen you contact support.
Creating a transaction answers 202 Accepted straight away, and tax is calculated just after. Check processingStatus before you read the tax totals.
v1
LegacyThe original Kintsugi API, versioned in the path. It remains the default in these docs and is documented exactly as before, so existing integrations can keep running with confidence. New integrations should start on the Tenanted API.