Head to head · Tax calculate · October 2026 research run
Quaderno vs Vertex O Series
Quaderno scores 59.5 (C) on agent readiness against Vertex O Series's 54.7 (C), and leads in 5 of 7 scored categories. Vertex O Series leads on security & auth and maintenance & community. Both do tax calculate.
Which one, for what
Quaderno C
Good for An agent working for a SaaS, digital-goods or e-commerce seller that needs a tax rate at checkout, a record of each sale with location evidence, and compliant invoices, including Spanish Verifactu and TicketBAI.
Ahead on
- Reliability, 91 against 65
- Agent ergonomics, 56 against 51
- Payments & pricing, 30 against 0
- Transparency & trust, 76 against 68
Watch for
One API key reads and writes everything its user can reach. Scopes exist only on Connect OAuth tokens (read_only, read_write)
Good for An agent working inside a company that already has an O Series licence, for quotes, invoice tax, tax area lookups and tax configuration across sales tax, use tax and VAT.
Ahead on
- Security & auth, 57 against 39
- Maintenance & community, 62 against 28
Watch for
No public price, free tier or self-serve signup. The security guide sends new users to the Vertex sales team for an account
Score by category
| Category | Weight this run | Quaderno | Vertex O Series | Edge |
|---|---|---|---|---|
| Reliability | 16%20 | 91 | 65 | Quaderno +26 |
| Performance | 10%pending | pending | pending | not scored in this run |
| Schema & documentation | 13%16.2 | 77 | 74 | Quaderno +3 |
| Agent ergonomics | 13%16.2 | 56 | 51 | Quaderno +5 |
| Security & auth | 14%17.5 | 39 | 57 | Vertex O Series +18 |
| Payments & pricing | 10%12.5 | 30 | 0 | Quaderno +30 |
| Task success | 10%pending | pending | pending | not scored in this run |
| Maintenance & community | 7%8.8 | 28 | 62 | Vertex O Series +34 |
| Transparency & trust | 7%8.8 | 76 | 68 | Quaderno +8 |
| Negative events | ≤15 | 0 | 0 | |
| Total | 59.5 · C | 54.7 · C |
Facts side by side
| Fact | Quaderno | Vertex O Series |
|---|---|---|
| Kind | HTTP API | HTTP API |
| Vendor | Recrea Systems, SL | Vertex, Inc. |
| Hosted endpoint | https://quadernoapp.com/api | https://calcconnect.vertexsmb.com/vertex-ws/v2 |
| Transports | HTTP | HTTP |
| Auth | OAuth or key | OAuth |
| Pricing | Paid | Paid |
| x402 | no | no |
| Licence | Proprietary service under Quaderno's terms of service. The Ruby library on GitHub is MIT | Proprietary service under a customer agreement with Vertex, Inc. that isn't published |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| Last release | 2026-07-04 | 2026-09-25 |
| Terms last updated | 2026-09-15 | no date given |
| Privacy policy last updated | 2024-05-16 | no date given |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | yes | not found in the text |
| Terms restrict benchmarking | yes | not found in the text |
| Terms or service can change without notice | yes | not found in the text |
| Arbitration or class-action waiver | not found in the text | not found in the text |
| Popularity | 15 stars | none |
Verdicts
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.
Vertex O Series
Public OpenAPI 3.0 specs cover calculation, transaction management, tax area lookup and tax configuration, and guides are served as Markdown. Access needs a sales contract. No price, free tier, sandbox signup, calculation rate limit, idempotency key or official SDK was found in the reviewed documentation.
Before you call either
Quaderno
- Call GET https://quadernoapp.com/api/authorization first. Its
hrefgives the account subdomain that every other call needs - Before retrying a failed POST /transactions, list invoices by
processor_idto check whether the sale was recorded. There is no idempotency key - Treat GET /invoices/{id}/deliver as a write. It emails the invoice to the customer
- Correct a final invoice with a credit note. DELETE on invoices returns 410 and PUT accepts only notes, tags, metadata and address fields
- Read X-RateLimit-Remaining and X-RateLimit-Reset, and page with
created_beforeandlimitup to 100
Vertex O Series
- Cache the access token for its 3,599-second life. The standard token endpoint allows 10 requests per 8 hours, and tokenguard.vertexcloud.com returns a cached token
- Send no
Authorization: Bearerheader to /oauth/token, and put the client id and secret in the body or a Basic header. Credentials in the URL are rejected - Set
saleMessageTypeto QUOTATION for an estimate. INVOICE is stored for reporting and remittance - Call GET /v2/transaction-exists/{transactionid} before retrying a failed INVOICE. No idempotency key is documented
- Delete, reverse or roll back a Cloud transaction within 90 days of calculation. Later requests can cause calculation errors or duplicates
Questions
Which is better for AI agents, Quaderno or Vertex O Series?
Quaderno scores 59.5 (C) on agent readiness against Vertex O Series's 54.7 (C), and leads in 5 of 7 scored categories. Vertex O Series leads on security & auth and maintenance & community.
Do Quaderno and Vertex O Series need an API key?
Quaderno takes an API key or an OAuth sign-in. Vertex O Series uses an OAuth sign-in.
Can an agent call Quaderno and Vertex O Series without installing anything?
Yes. Quaderno has a hosted endpoint at https://quadernoapp.com/api and Vertex O Series at https://calcconnect.vertexsmb.com/vertex-ws/v2.
Other comparisons with Quaderno or Vertex O Series
Machine-readable
- This page as Markdown
/compare/quaderno-vs-vertex-tax.md· slim.min.md· JSON.json(or sendAccept: text/markdown) - Each listing in full
/api/v1/tools/quaderno.json·/api/v1/tools/vertex-tax.json - From a terminal
anchor compare quaderno vertex-tax(the CLI) - Over MCP
compare_tools {"a": "quaderno", "b": "vertex-tax"}at/mcp, no key