Head to head · Tax calculate · October 2026 research run
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.
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 this run | Numeral | Zamp | Edge |
|---|---|---|---|---|
| Reliability | 16%20 | 25 | 72 | Zamp +47 |
| Performance | 10%pending | pending | pending | not scored in this run |
| Schema & documentation | 13%16.2 | 87 | 44 | Numeral +43 |
| Agent ergonomics | 13%16.2 | 71 | 64 | Numeral +7 |
| Security & auth | 14%17.5 | 47 | 40 | Numeral +7 |
| Payments & pricing | 10%12.5 | 10 | 20 | Zamp +10 |
| Task success | 10%pending | pending | pending | not scored in this run |
| Maintenance & community | 7%8.8 | 60 | 42 | Numeral +18 |
| Transparency & trust | 7%8.8 | 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
- Send
X-API-Version: 2026-03-01on every call tohttps://api.numeralhq.com. Merchant, platform and certificate endpoints reject requests without it - Commit with a stable
reference_order_id. OnREFERENCE_ORDER_ID_ALREADY_EXISTSlook up the existing transaction, becauseIdempotency-Keyis ignored - Commit before the calculation's
expires_at. If it has expired, calculate again and commit the newcalculation_idwith the originalreference_order_id - Send
amountas the line total in minor units to/tax/calculationsand as the per-unit price to/tax/platform/calculations - Start with an
sk_test_key. Certificate endpoints and MCP certificate tools are live only and answerTESTMODE_NOT_SUPPORTEDorlive_mode_required
Zamp
- Call
POST /calculationsfor a quote andPOST /transactionsonly when the sale is final. Put the returnedtaxDueintaxCollectedwhen posting - Keep transaction and line item ids to 25 characters. A repeated
POST /transactionswith an existing id returns 409CONFLICT, so a retry doesn't create a second record - For a refund, post a new transaction with
parentIdset to the sale's id and a negativequantity. Never send a negativeamounton a line item - Send
shipToAddress.stateandcountryset to CA for Canadian orders.POST /addressesvalidates US addresses only - Page lists with
limit(1 to 100, default 10) andcursoruntilnextCursoris null.GET /transactionsreturns only transactions written with the same key - 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.
Other comparisons with Numeral or Zamp
Machine-readable
- This page as Markdown
/compare/numeral-vs-zamp.md· slim.min.md· JSON.json(or sendAccept: text/markdown) - Each listing in full
/api/v1/tools/numeral.json·/api/v1/tools/zamp.json - From a terminal
anchor compare numeral zamp(the CLI) - Over MCP
compare_tools {"a": "numeral", "b": "zamp"}at/mcp, no key