Avalara AvaTax vs Quaderno

Avalara AvaTax

The REST API has a public Swagger file with 491 operations, a Markdown page per endpoint and a 90-day trial with no card. Production rate limits and prices per transaction are not published, the API patch notes stop at April 2023, and the tax calculation service was degraded for about 23 hours on 5 and 6 October 2026.

Quaderno

A public OpenAPI 3.1 spec covers 92 operations, with a free sandbox and a status page showing no incident since July 2025. The API key has full account access, there are no idempotency keys, and the newest public API version is dated October 2024.

Avalara AvaTax

1. Omit type or send SalesOrder for an estimate. A type ending in Invoice is recorded, and commit set to true locks it for reporting
2. Retry a timed-out invoice with CreateOrAdjustTransaction, not CreateTransaction, which errors when a committed transaction has the same code
3. Use sandbox-rest.avatax.com with sandbox credentials for tests. Production is rest.avatax.com and the two accounts are separate
4. Add $include=SummaryOnly or LinesOnly to shrink transaction responses, and page lists with $top (1,000 at most) and $skip
5. Call /api/v2/utilities/ping first. It answers without credentials and shows whether the credentials sent were accepted

Quaderno

1. Call GET https://quadernoapp.com/api/authorization first. Its href gives the account subdomain that every other call needs
2. Before retrying a failed POST /transactions, list invoices by processor_id to check whether the sale was recorded. There is no idempotency key
3. Treat GET /invoices/{id}/deliver as a write. It emails the invoice to the customer
4. Correct a final invoice with a credit note. DELETE on invoices returns 410 and PUT accepts only notes, tags, metadata and address fields
5. Read X-RateLimit-Remaining and X-RateLimit-Reset, and page with created_before and limit up to 100