# Quaderno vs TaxJar

> Quaderno scores 59.5 (C) on agent readiness against TaxJar's 57.6 (C), and leads in 3 of 7 scored categories. TaxJar leads on agent ergonomics and maintenance & community. Both do tax calculate. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/quaderno-vs-taxjar
- Markdown: https://www.anchorterminal.com/compare/quaderno-vs-taxjar.md (~1,950 tokens)
- Slim: https://www.anchorterminal.com/compare/quaderno-vs-taxjar.min.md (~680 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/quaderno-vs-taxjar.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-08

Quaderno scores 59.5 (C) on agent readiness against TaxJar's 57.6 (C), and leads in 3 of 7 scored categories. TaxJar leads on agent ergonomics and maintenance & community. Both do tax calculate.

- Quaderno: grade C, 59.5/100, rank #377 of 629. Markdown https://www.anchorterminal.com/tools/quaderno.md · JSON https://www.anchorterminal.com/api/v1/tools/quaderno.json
- TaxJar: grade C, 57.6/100, rank #417 of 629. Markdown https://www.anchorterminal.com/tools/taxjar.md · JSON https://www.anchorterminal.com/api/v1/tools/taxjar.json

## 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 84
- Schema & documentation, 77 against 48
- Transparency & trust, 76 against 71

Watch for: One API key reads and writes everything its user can reach. Scopes exist only on Connect OAuth tokens (read_only, read_write)

### TaxJar (C)

Good for: An agent working for a US seller that needs sales tax on an order at checkout and a record of orders and refunds for state reporting, with exempt customers handled by ID.

Ahead on:
- Agent ergonomics, 61 against 56
- Maintenance & community, 64 against 28

Also in its favour:
- Free to start without a card

Watch for: No OpenAPI spec or llms.txt was found. The taxjar/openapi repository on GitHub holds only a README


## Score by category

| Category | Weight | Quaderno | TaxJar | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 91 | 84 | Quaderno +7 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 77 | 48 | Quaderno +29 |
| Agent ergonomics | 13% (16.2 this run) | 56 | 61 | TaxJar +5 |
| Security & auth | 14% (17.5 this run) | 39 | 43 | TaxJar +4 |
| Payments & pricing | 10% (12.5 this run) | 30 | 30 | even |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 28 | 64 | TaxJar +36 |
| Transparency & trust | 7% (8.8 this run) | 76 | 71 | Quaderno +5 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **59.5 · C** | **57.6 · C** | |

## Facts side by side

| Fact | Quaderno | TaxJar |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Recrea Systems, SL | TaxJar (Stripe) |
| Hosted endpoint | `https://quadernoapp.com/api` | `https://api.taxjar.com/v2` |
| Transports | HTTP | HTTP |
| Auth | OAuth or key | API key |
| 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 TaxJar's terms of service and API licence agreement. The official API clients on GitHub are MIT |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| Last release | 2026-07-04 | 2026-09-02 |
| Terms last updated | 2026-09-15 | 2026-05-14 |
| Privacy policy last updated | 2024-05-16 | 2022-01-07 |
| 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 | yes |
| 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 | 57 stars, 95k npm/wk, 50k PyPI/wk |

## 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.

**TaxJar.** A 21-operation REST API with a no-card 30-day trial, caller-chosen transaction IDs that make order pushes safe to repeat, and no status-page incident since March 2026. No OpenAPI spec or llms.txt was found, the API changelog stops at January 2022, tokens carry no scopes, and calculation is US-only for new accounts.

## Before you call either

### 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

### TaxJar

1. Send `x-api-version: 2022-01-24` on every call. Accounts opened before 3 February 2022 default to an older version with weaker validation
2. Pass `nexus_addresses[]` or keep nexus states in the account. Without nexus the API returns zero tax and reports no error
3. Create orders with your own `transaction_id`. On 422 the order already exists, so send a PUT to update it
4. Post JSON with `Content-Type: application/json`. Form-encoded arrays such as `line_items[]` can return 406
5. Cache calculations and skip states without nexus. Each calculation or rate lookup counts as a tenth of an order, errors included

## Questions

### Which is better for AI agents, Quaderno or TaxJar?

Quaderno scores 59.5 (C) on agent readiness against TaxJar's 57.6 (C), and leads in 3 of 7 scored categories. TaxJar leads on agent ergonomics and maintenance & community.

### Do Quaderno and TaxJar need an API key?

Quaderno takes an API key or an OAuth sign-in. TaxJar needs an API key.

### Can an agent call Quaderno and TaxJar without installing anything?

Yes. Quaderno has a hosted endpoint at https://quadernoapp.com/api and TaxJar at https://api.taxjar.com/v2.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/quaderno-vs-taxjar.json, and with the fewest tokens: https://www.anchorterminal.com/compare/quaderno-vs-taxjar.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "quaderno", "b": "taxjar"}`. From a terminal: `anchor compare quaderno taxjar`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/quaderno.json and https://www.anchorterminal.com/api/v1/tools/taxjar.json

## Other comparisons with Quaderno or TaxJar

- [Anrok vs Quaderno](https://www.anchorterminal.com/compare/anrok-vs-quaderno.md)
- [Anrok vs TaxJar](https://www.anchorterminal.com/compare/anrok-vs-taxjar.md)
- [Avalara AvaTax vs Quaderno](https://www.anchorterminal.com/compare/avalara-vs-quaderno.md)
- [Avalara AvaTax vs TaxJar](https://www.anchorterminal.com/compare/avalara-vs-taxjar.md)
- [Quaderno vs Vertex O Series](https://www.anchorterminal.com/compare/quaderno-vs-vertex-tax.md)
- [TaxJar vs Vertex O Series](https://www.anchorterminal.com/compare/taxjar-vs-vertex-tax.md)