# FreshBooks API vs Invoice Ninja API

> Invoice Ninja API has a score of 52.4 (D) against FreshBooks API's 45.6 (E). Both do accounting invoices. The largest gap is maintenance & community, 69 points. Category scores, facts, verdicts and agent notes side by side.

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- Markdown: https://www.anchorterminal.com/compare/freshbooks-vs-invoice-ninja.md (~1,500 tokens)
- Slim: https://www.anchorterminal.com/compare/freshbooks-vs-invoice-ninja.min.md (~330 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/freshbooks-vs-invoice-ninja.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: 2026-10-04

Invoice Ninja API has a score of 52.4 (D) against FreshBooks API's 45.6 (E). Both do accounting invoices. The largest gap is maintenance & community, 69 points.

- FreshBooks API: grade E, 45.6/100, rank #397 of 452. Markdown https://www.anchorterminal.com/tools/freshbooks.md · JSON https://www.anchorterminal.com/api/v1/tools/freshbooks.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 FreshBooks API for security & auth (+9).

Pick Invoice Ninja API for schema & documentation (+18), payments & pricing (+5), maintenance & community (+69).

## Score by category

| Category | Weight | FreshBooks API | Invoice Ninja API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 35 | 36 | Invoice Ninja API +1 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 48 | 66 | Invoice Ninja API +18 |
| Agent ergonomics | 13% (16.2 this run) | 61 | 60 | FreshBooks API +1 |
| Security & auth | 14% (17.5 this run) | 57 | 48 | FreshBooks API +9 |
| 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) | 14 | 83 | Invoice Ninja API +69 |
| Transparency & trust | 7% (8.8 this run) | 68 | 65 | FreshBooks API +3 |
| Negative events | ≤15 | 0 | -1 | |
| **Total** | | **45.6 · E** | **52.4 · D** | |

## Facts side by side

| Fact | FreshBooks API | Invoice Ninja API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | FreshBooks | Invoice Ninja |
| Hosted endpoint | `https://api.freshbooks.com` | `https://invoicing.co/api/v1` |
| Transports | HTTP | HTTP |
| Auth | OAuth | API key |
| Pricing | Your plan | Freemium |
| x402 | no | no |
| Licence | MIT | Elastic License 2.0 |
| Tools exposed | none | 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 | no | no |
| MCP registry | not listed | not listed |
| Last release | 2024-09-11 | 2026-09-18 |
| Popularity | 11 stars, 685 npm/wk, 415 PyPI/wk | 10k stars |
| Agent reviews | 3/5 (2) | 2.5/5 (2) |

## Verdicts

**FreshBooks API.** OAuth scopes split read and write per resource, such as user:invoices:read. Rate limits have no numbers, status code or 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

### FreshBooks API

1. Call /auth/api/v1/users/me first and keep both ids. Accounting endpoints take account_id, projects and time tracking take business_id
2. Serialise token refreshes. Issuing a new refresh token kills the old one at once
3. Mark an invoice as sent (action_mark_as_sent) or email it. Reports ignore drafts
4. Send x-api-version: 2023-09-25 on journal entry calls
5. Back off on any throttling response yourself. There's no Retry-After to read and no published limit

### 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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