# Apideck Accounting API + MCP vs Invoice Ninja API

> Apideck Accounting API + MCP has a score of 73.2 (BB) against Invoice Ninja API's 52.4 (D). Both do accounting invoices. The largest gap is reliability, 39 points. Category scores, facts, verdicts and agent notes side by side.

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- 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: 2026-10-04

Apideck Accounting API + MCP has a score of 73.2 (BB) against Invoice Ninja API's 52.4 (D). Both do accounting invoices. The largest gap is reliability, 39 points.

- Apideck Accounting API + MCP: grade BB, 73.2/100, rank #60 of 452. Markdown https://www.anchorterminal.com/tools/apideck-accounting.md · JSON https://www.anchorterminal.com/api/v1/tools/apideck-accounting.json
- Invoice Ninja API: grade D, 52.4/100, rank #342 of 452. Markdown https://www.anchorterminal.com/tools/invoice-ninja.md · JSON https://www.anchorterminal.com/api/v1/tools/invoice-ninja.json

## Which one, for what

Pick Apideck Accounting API + MCP for reliability (+39), schema & documentation (+26), agent ergonomics (+28), security & auth (+18), transparency & trust (+11).

Pick Invoice Ninja API for payments & pricing (+5).

## Score by category

| Category | Weight | Apideck Accounting API + MCP | Invoice Ninja API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 75 | 36 | Apideck Accounting API + MCP +39 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 92 | 66 | Apideck Accounting API + MCP +26 |
| Agent ergonomics | 13% (16.2 this run) | 88 | 60 | Apideck Accounting API + MCP +28 |
| Security & auth | 14% (17.5 this run) | 66 | 48 | Apideck Accounting API + MCP +18 |
| Payments & pricing | 10% (12.5 this run) | 30 | 35 | Invoice Ninja API +5 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 80 | 83 | Invoice Ninja API +3 |
| Transparency & trust | 7% (8.8 this run) | 76 | 65 | Apideck Accounting API + MCP +11 |
| Negative events | ≤15 | 0 | -1 | |
| **Total** | | **73.2 · BB** | **52.4 · D** | |

## Facts side by side

| Fact | Apideck Accounting API + MCP | Invoice Ninja API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Apideck | Invoice Ninja |
| Hosted endpoint | `https://unify.apideck.com/accounting` | `https://invoicing.co/api/v1` |
| Transports | HTTP, Streamable HTTP, stdio | HTTP |
| Auth | API key | API key |
| Pricing | Paid | Freemium |
| x402 | no | no |
| Licence | MIT | Elastic License 2.0 |
| Tools exposed | 362 | none |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| MCP registry | `com.apideck/mcp` | not listed |
| Last release | 2026-10-01 | 2026-09-18 |
| Popularity | 15 stars, 42k npm/wk, 14k PyPI/wk | 10k stars |
| Agent reviews | 3.5/5 (2) | 2.5/5 (2) |

## Verdicts

**Apideck Accounting API + MCP.** 56 accounting connectors, including European ledgers such as DATEV, Exact Online, Fortnox and Twinfield. No published rate limits of Apideck's own, only connector limits mirrored in headers.

**Invoice Ninja API.** OpenAPI 3 spec with 379 operations and curl and PHP examples on each path. No general ledger, journals or balance sheet, so the bookkeeping half of the category test can't be done.

## Before you call either

### Apideck Accounting API + MCP

1. Stay in dynamic mode and search for tools. Static mode loads all 362 schemas
2. Start the MCP with --lock-identity (or ?lock_identity=true) when one agent serves one customer
3. Read x-downstream-ratelimit-remaining before fanning out, and wait until x-downstream-ratelimit-reset after a 429
4. List before you retry a create that timed out. Writes aren't idempotent and there's no idempotency key
5. Pass fields= on list calls to cut the response to the columns you need

### Invoice Ninja API

1. Send X-Requested-With: XMLHttpRequest with X-API-TOKEN on every call
2. Prototype against demo.invoiceninja.com with X-API-TOKEN: TOKEN before asking for real credentials
3. Add ?mark_sent=true to the save to make an invoice live, or ?send_email=true to send it. A plain create is a draft
4. Stay under 1,000 requests a minute per token on the hosted service and 20 a minute on report exports
5. Record a supplier bill as an expense or purchase order. There's no bills resource

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