# Fonoa vs Numeral

> Fonoa scores 51.7 (D) on agent readiness against Numeral's 49.3 (D), and leads in 2 of 7 scored categories. Numeral leads on schema & documentation, agent ergonomics, payments & pricing and maintenance & community. Both do tax calculate. Category scores, facts, verdicts and…

- Canonical: https://www.anchorterminal.com/compare/fonoa-vs-numeral
- Markdown: https://www.anchorterminal.com/compare/fonoa-vs-numeral.md (~2,200 tokens)
- Slim: https://www.anchorterminal.com/compare/fonoa-vs-numeral.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/fonoa-vs-numeral.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

Fonoa scores 51.7 (D) on agent readiness against Numeral's 49.3 (D), and leads in 2 of 7 scored categories. Numeral leads on schema & documentation, agent ergonomics, payments & pricing and maintenance & community. Both do tax calculate.

- Fonoa: grade D, 51.7/100, rank #575 of 722. Markdown https://www.anchorterminal.com/tools/fonoa.md · JSON https://www.anchorterminal.com/api/v1/tools/fonoa.json
- 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

## Which one, for what

### Fonoa (D)

Good for: An agent working for a company that already has a Fonoa contract and needs tax ID validation, VAT or GST calculation, or e-invoice reporting across many countries through one API.

Ahead on:
- Reliability, 66 against 25

Watch for: No self-serve signup. Sandbox, demo and production keys are issued by Fonoa after contact by email or the sales form

### 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 68
- Agent ergonomics, 71 against 64
- Payments & pricing, 10 against 3
- Maintenance & community, 60 against 49

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


## Score by category

| Category | Weight | Fonoa | Numeral | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 66 | 25 | Fonoa +41 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 68 | 87 | Numeral +19 |
| Agent ergonomics | 13% (16.2 this run) | 64 | 71 | Numeral +7 |
| Security & auth | 14% (17.5 this run) | 47 | 47 | even |
| Payments & pricing | 10% (12.5 this run) | 3 | 10 | Numeral +7 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 49 | 60 | Numeral +11 |
| Transparency & trust | 7% (8.8 this run) | 48 | 45 | Fonoa +3 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **51.7 · D** | **49.3 · D** | |

## Facts side by side

| Fact | Fonoa | Numeral |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Fonoa Technologies Limited | Numeral Two, Inc. |
| Hosted endpoint | `https://api.fonoa.com` | `https://api.numeralhq.com` |
| Transports | HTTP | HTTP, Streamable HTTP |
| Auth | API key | API key |
| Pricing | Paid | Paid |
| x402 | no | no |
| Licence | Proprietary service. The API contract is not published. The public Terms of Service took effect on 14 May 2020 and name older seller sites | Proprietary service under Numeral's terms of service. The Go, Python and Node SDKs are Apache-2.0 |
| Tools exposed | none | 14 |
| Read-only variant documented | no | yes |
| llms.txt | yes | yes |
| Last release | 2026-10-02 | 2026-09-15 |
| Terms last updated | no document linked | no date given |
| Privacy policy last updated | no date given | no document linked |
| Customer content may train models |  | not found in the text |
| Terms restrict automated access |  | not found in the text |
| Terms restrict benchmarking |  | not found in the text |
| Terms or service can change without notice |  | not found in the text |
| Arbitration or class-action waiver |  | yes |
| Popularity | none | 0 stars, 9 npm/wk, 19 PyPI/wk |

## Verdicts

**Fonoa.** The API reference is served as Markdown with an OpenAPI definition on each endpoint page, and e-invoicing submissions are idempotent by `transaction_id`. API keys are issued by Fonoa staff after contact, no price, rate limit or changelog is published, and the only public terms date from May 2020 and cover older seller sites.

**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.

## Before you call either

### Fonoa

1. Send the key in the `Ocp-Apim-Subscription-Key` header. Use the sandbox key at https://sandbox.fonoa.com and the production key at https://api.fonoa.com
2. Treat validations and e-invoicing submissions as asynchronous. POST, then poll the GET endpoint or wait for the webhook, and avoid tight polling
3. Reuse the same `transaction_id` on a retry of `/v1/transactions`. A transaction already processed is not processed again
4. Commit a calculation with POST `/tax/v2/calculations/<uuid>/commit` only when the sale is final. The commit adds it to revenue tracking
5. Ask the Fonoa contact to configure webhooks. There is no API for it, and always fetch `resource_url` as given in the webhook

### 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`

## Questions

### Which is better for AI agents, Fonoa or Numeral?

Fonoa scores 51.7 (D) on agent readiness against Numeral's 49.3 (D), and leads in 2 of 7 scored categories. Numeral leads on schema & documentation, agent ergonomics, payments & pricing and maintenance & community.

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

Both need an API key.

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

Yes. Fonoa has a hosted endpoint at https://api.fonoa.com and Numeral at https://api.numeralhq.com.


## For agents

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

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