Anrok vs TaxCloud

Anrok

The public OpenAPI 3.1 spec covers 26 operations with typed error codes, and the remote MCP server uses OAuth 2.1 with six scopes and keeps voids, refunds and filing approval away from the model. Access needs a seller account arranged through sales, API keys carry no scopes, and no API changelog, SDK or subprocessor list was found.

TaxCloud

A 30-operation REST API with a public OpenAPI 3.1 contract, llms.txt, Markdown docs and a 30-day trial that needs no card. The vendor publishes no rate limit numbers, no SLA, no API changelog and no official v3 client library, and the security page names no audit or certification.

Anrok

1. Send every call as a POST with a JSON body to https://api.anrok.com, including reads such as /v1/seller/products/list
2. Call createEphemeral for a quote and createOrUpdate only when the invoice is final. createOrUpdate saves the transaction for filing
3. Reuse the same transaction id on a retry. createOrUpdate overwrites by id, so a repeat doesn't create a second record
4. Expect transactionFrozenForFiling once a transaction is on a filed return. Negate it with createNegation and write a new id with a suffix such as :s2
5. On 429 wait the number of seconds in Retry-After. The default limit is 10 requests a second per seller account

TaxCloud

1. Send X-API-KEY on every call and put the connection ID in the path, as in /tax/connections/{connectionId}/carts. A wrong ID returns 404
2. Mark nexus states active in the account first. With none active the API returns zero tax and no error
3. Use a separate test connection. There is no sandbox, and orders on a live connection go into filing
4. Pass a stable idempotencyKey on refunds, and never convert the same cart twice. A second conversion creates a duplicate liability
5. Void a wrong order before 12:00 AM Eastern on the 10th of the month after its completedDate. Later requests return 422