# TaxJar vs Zamp

> TaxJar scores 57.6 (C) on agent readiness against Zamp's 49.5 (D), and leads in 6 of 7 scored categories. Both do tax calculate. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/taxjar-vs-zamp
- Markdown: https://www.anchorterminal.com/compare/taxjar-vs-zamp.md (~2,150 tokens)
- Slim: https://www.anchorterminal.com/compare/taxjar-vs-zamp.min.md (~580 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/taxjar-vs-zamp.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

TaxJar scores 57.6 (C) on agent readiness against Zamp's 49.5 (D), and leads in 6 of 7 scored categories. Both do tax calculate.

- TaxJar: grade C, 57.6/100, rank #470 of 722. Markdown https://www.anchorterminal.com/tools/taxjar.md · JSON https://www.anchorterminal.com/api/v1/tools/taxjar.json
- Zamp: grade D, 49.5/100, rank #609 of 722. Markdown https://www.anchorterminal.com/tools/zamp.md · JSON https://www.anchorterminal.com/api/v1/tools/zamp.json

## Which one, for what

### 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:
- Reliability, 84 against 72
- Payments & pricing, 30 against 20
- Maintenance & community, 64 against 42
- Transparency & trust, 71 against 50

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

### Zamp (D)

Good for: An agent working for a US or Canadian seller that wants Zamp's team to register, file and remit, and needs calculation and transaction sync through a small API.

Watch for: No OpenAPI file for the API. The one file on the docs host is the documentation platform's plant store sample


## Score by category

| Category | Weight | TaxJar | Zamp | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 84 | 72 | TaxJar +12 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 48 | 44 | TaxJar +4 |
| Agent ergonomics | 13% (16.2 this run) | 61 | 64 | Zamp +3 |
| Security & auth | 14% (17.5 this run) | 43 | 40 | TaxJar +3 |
| Payments & pricing | 10% (12.5 this run) | 30 | 20 | TaxJar +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 64 | 42 | TaxJar +22 |
| Transparency & trust | 7% (8.8 this run) | 71 | 50 | TaxJar +21 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **57.6 · C** | **49.5 · D** | |

## Facts side by side

| Fact | TaxJar | Zamp |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | TaxJar (Stripe) | Zamp Inc. |
| Hosted endpoint | `https://api.taxjar.com/v2` | `https://api.zamp.com` |
| Transports | HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Paid | Paid |
| x402 | no | no |
| Licence | Proprietary service under TaxJar's terms of service and API licence agreement. The official API clients on GitHub are MIT | Proprietary service under Zamp's Standard Terms and Conditions, which form part of a signed Order Form. The sandbox has its own Developer trial terms |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| Last release | 2026-09-02 | 2026-08-31 |
| Terms last updated | 2026-05-14 | no date given |
| Privacy policy last updated | 2022-01-07 | 2025-02-11 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | not found in the text | yes |
| Terms restrict benchmarking | yes | yes |
| Terms or service can change without notice | not found in the text | not found in the text |
| Arbitration or class-action waiver | not found in the text | not found in the text |
| Popularity | 57 stars, 95k npm/wk, 50k PyPI/wk | none |

## Verdicts

**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.

**Zamp.** A free 30-day sandbox key needs no card or sales call, and the docs are served as Markdown with llms.txt and a published limit of 1,000 requests a minute. There is no OpenAPI file, SDK, API changelog or published price, production keys come with a sales-led account, and the site footer says SOC 2 compliance is in progress.

## Before you call either

### 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

### Zamp

1. Call `POST /calculations` for a quote and `POST /transactions` only when the sale is final. Put the returned `taxDue` in `taxCollected` when posting
2. Keep transaction and line item ids to 25 characters. A repeated `POST /transactions` with an existing id returns 409 `CONFLICT`, so a retry doesn't create a second record
3. For a refund, post a new transaction with `parentId` set to the sale's id and a negative `quantity`. Never send a negative `amount` on a line item
4. Send `shipToAddress.state` and `country` set to CA for Canadian orders. `POST /addresses` validates US addresses only
5. Page lists with `limit` (1 to 100, default 10) and `cursor` until `nextCursor` is null. `GET /transactions` returns only transactions written with the same key
6. Don't store sensitive or personal data in the sandbox. Trial data is deleted after 30 days and the trial terms forbid live customer data

## Questions

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

TaxJar scores 57.6 (C) on agent readiness against Zamp's 49.5 (D), and leads in 6 of 7 scored categories.

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

Both need an API key.

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

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


## For agents

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

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