# Numeral vs Zamp

> Zamp and Numeral score within a point of each other on agent readiness, 49.5 (D) and 49.3 (D). Numeral leads on schema & documentation, agent ergonomics, security & auth and maintenance & community. Both do tax calculate. Category scores, facts, verdicts and agent notes side by…

- Canonical: https://www.anchorterminal.com/compare/numeral-vs-zamp
- Markdown: https://www.anchorterminal.com/compare/numeral-vs-zamp.md (~2,300 tokens)
- Slim: https://www.anchorterminal.com/compare/numeral-vs-zamp.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/numeral-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

Zamp and Numeral score within a point of each other on agent readiness, 49.5 (D) and 49.3 (D). Numeral leads on schema & documentation, agent ergonomics, security & auth and maintenance & community. Both do tax calculate.

- Numeral: grade D, 49.3/100, rank #611 of 722. Markdown https://www.anchorterminal.com/tools/numeral.md · JSON https://www.anchorterminal.com/api/v1/tools/numeral.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

### Numeral (D)

Good for: An agent working for a seller or platform that has a Numeral account and needs tax at checkout, committed transactions for filing, and read access to nexus, registrations and filings through MCP.

Ahead on:
- Schema & documentation, 87 against 44
- Agent ergonomics, 71 against 64
- Security & auth, 47 against 40
- Maintenance & community, 60 against 42

Watch for: No status page, uptime SLA or numeric rate limit was found. The product page says rate limits can be removed on request

### 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.

Ahead on:
- Reliability, 72 against 25
- Payments & pricing, 20 against 10
- Transparency & trust, 50 against 45

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

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 | Numeral | Zamp | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 25 | 72 | Zamp +47 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 87 | 44 | Numeral +43 |
| Agent ergonomics | 13% (16.2 this run) | 71 | 64 | Numeral +7 |
| Security & auth | 14% (17.5 this run) | 47 | 40 | Numeral +7 |
| Payments & pricing | 10% (12.5 this run) | 10 | 20 | Zamp +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 60 | 42 | Numeral +18 |
| Transparency & trust | 7% (8.8 this run) | 45 | 50 | Zamp +5 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **49.3 · D** | **49.5 · D** | |

## Facts side by side

| Fact | Numeral | Zamp |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Numeral Two, Inc. | Zamp Inc. |
| Hosted endpoint | `https://api.numeralhq.com` | `https://api.zamp.com` |
| Transports | HTTP, Streamable HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Paid | Paid |
| x402 | no | no |
| Licence | Proprietary service under Numeral's terms of service. The Go, Python and Node SDKs are Apache-2.0 | 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 |
| Tools exposed | 14 | none |
| Read-only variant documented | yes | no |
| llms.txt | yes | yes |
| Last release | 2026-09-15 | 2026-08-31 |
| Terms last updated | no date given | no date given |
| Privacy policy last updated | no document linked | 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 | not found in the text | yes |
| Terms or service can change without notice | not found in the text | not found in the text |
| Arbitration or class-action waiver | yes | not found in the text |
| Popularity | 0 stars, 9 npm/wk, 19 PyPI/wk | none |

## Verdicts

**Numeral.** Docs are written for agents, with a public OpenAPI spec for 32 operations, Markdown pages, llms.txt and a remote MCP server whose 14 tools are read-only by default. No status page, numeric rate limit or SLA was found, the API ignores idempotency keys, and API access is sold on a custom plan after a demo.

**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

### Numeral

1. Send `X-API-Version: 2026-03-01` on every call to `https://api.numeralhq.com`. Merchant, platform and certificate endpoints reject requests without it
2. Commit with a stable `reference_order_id`. On `REFERENCE_ORDER_ID_ALREADY_EXISTS` look up the existing transaction, because `Idempotency-Key` is ignored
3. Commit before the calculation's `expires_at`. If it has expired, calculate again and commit the new `calculation_id` with the original `reference_order_id`
4. Send `amount` as the line total in minor units to `/tax/calculations` and as the per-unit price to `/tax/platform/calculations`
5. Start with an `sk_test_` key. Certificate endpoints and MCP certificate tools are live only and answer `TESTMODE_NOT_SUPPORTED` or `live_mode_required`

### 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, Numeral or Zamp?

Zamp and Numeral score within a point of each other on agent readiness, 49.5 (D) and 49.3 (D). Numeral leads on schema & documentation, agent ergonomics, security & auth and maintenance & community.

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

Both need an API key.

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

Yes. Numeral has a hosted endpoint at https://api.numeralhq.com and Zamp at https://api.zamp.com.


## For agents

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

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