Invoice Ninja API by Invoice Ninja

# Fix list: Invoice Ninja API

From Anchor Terminal's listing at https://www.anchorterminal.com/tools/invoice-ninja, the October 2026 research run, assessed 1 October 2026. Grade D, 52.4 out of 100.

This is everything the published grade says the listing lacks, the biggest possible gain to the total first. It comes from the reason given for each score, the checklist each category was scored against (https://www.anchorterminal.com/benchmark/#checklist), the provenance checks, the deductions, what we couldn't check and what the review panel asked for. A fix counts at the next check, once it's public.

For a coding agent working on Invoice Ninja API: work through the items below in the product, its docs and its public pages. Each category gives the reason for its score, with the points each checklist item earned, and the checklist itself, so the gap is the items that earned less than their points. Change the product, not the wording, and keep a note of what you changed and where it's published.

## 1. Reliability, 36 out of 100, up to 12.8 more on the total

Why it scored 36: Oh Dear status page watching invoiceninja.com and invoicing.co, with no API component and only seven days of history on view (10). /history returns 404, so we couldn't read the last 90 days (5). The docs give no numbers. The source sets 1,000 requests a minute per IP and per token on the hosted service, 20 a minute on report exports and no limit when self-hosted, which we counted at half (8). 429 appears only as a row in the error table (3). No SLA, and the terms say Invoice Ninja "strives to ensure maximum uptime" (0). GA (10).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-reliability):

Hosted APIs, MCP servers, models and platforms.

- 20, a public status page with component history (Statuspage, Instatus, BetterStack or the vendor's own).
- 0 to 30, the incident record for the last 90 days on that page. 30 for a clean record or trivial incidents only, 20 for minor incidents only, 10 for one major outage (an hour or more of a core API down, or errors across the board), 0 for several. 5 when there's no history we could read, and the note says so.
- 15, rate limits documented with numbers.
- 15, documented 429 or overload handling (Retry-After, backoff guidance), and idempotency keys or safe-retry guidance where writes are involved.
- 10, an SLA published for any paid tier.
- 10, the surface agents use is generally available, not beta or preview.

Local packages, SDKs, frameworks and stdio MCP servers.

- 20, installs from an official package with supported runtimes stated.
- 25, a public CI and test suite, passing on the default branch.
- 0 to 25, open crash or regression issues relative to activity (25 for few and handled, 0 for many, old and unanswered).
- 15, semver discipline and breaking changes called out in a changelog.
- 15, version 1.0 or later, or declared stable.

Protocols are read from their reference implementations, the public facilitators or servers, spec stability and test vectors.

## 2. Security & auth, 48 out of 100, up to 9.1 more on the total

Why it scored 48: API tokens per user, created and revoked under Settings, Account Management, Integrations, in a header and never a URL. No per-token scopes (20). No read-only token. Invoices stay drafts unless the call asks otherwise (5). Returns client and product text that other people wrote, and two stored XSS advisories in March 2026 came through invoice line items and product notes, with no injection guidance for API consumers (3). Activity log and an activities report export (10). SECURITY.md with a disclosure email and advisories published on GitHub. No security.txt, bug bounty or certification found (10).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-security):

- 0 to 30, the credential model. 30 for OAuth 2.1 with scopes, or scoped and revocable keys with rotation. 20 for plain revocable API keys. 10 for one all-powerful key. 10 off when a secret can travel in a URL query string as a documented option.
- 0 to 20, read-only or least-privilege modes, and confirmation or approval for destructive actions.
- 0 to 15, prompt-injection posture where the tool returns untrusted content (documented mitigations or guidance). A tool that returns no untrusted content gets 10.
- 0 to 15, audit logs or per-call visibility for the operator.
- 0 to 20, a security programme. security.txt or a disclosure policy, a bug bounty, SOC 2 or ISO 27001, advisories handled in public.

Models are read for retention, whether API data trains models (and whether that's off by default), zero-retention options and certifications. Frameworks for telemetry defaults, approval hooks, guardrails and sandboxing.

## 3. Payments & pricing, 35 out of 100, up to 8.1 more on the total

Why it scored 35: No x402, MPP or L402 (0). Hosted plan prices are public, Pro $14 a month, Enterprise $18 to $300, Premium Business from $280 a year (10). Hosted Free (5 clients, no card) has no REST API, but self-hosting is free with every feature, which we counted at three quarters (15). The public demo at demo.invoiceninja.com takes the token TOKEN with no signup, though it's a shared demo, not your own company (10).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-payments):

The published rubric, also on the [x402 page](https://www.anchorterminal.com/x402/).

- 40, a machine payment protocol (x402, MPP or L402) on the tool's own endpoints. 10 to 30 when it covers only some endpoints or only goes through a third party, and the note says which.
- 20, per-call or per-unit pricing published without a login. 10 for public plan-only pricing, 0 for "contact sales" or prices behind a login.
- 20, a free tier or trial that doesn't need a card.
- 20, autonomous onboarding, meaning an agent can get access without a person signing up in a browser (keyless use, x402, a programmatic key API).

Payment platforms and agent wallets rarely charge for their own API over a machine protocol, so the first line has steps for them, and the highest one that applies counts. 40 when x402, MPP or L402 runs on all their own endpoints, 30 when it runs on part of their own API, 25 when their merchants can accept one, 20 for running a facilitator, 15 for paying as a buyer, and 0 when the only protocol is their own. Merchant acceptance sits above a facilitator because the platform's own customers can charge agents through it, while a facilitator settles for sellers who wire up the protocol themselves. The counter-argument (a facilitator does more for the protocol as a whole) has a point. Each note says which step applied.

Open-source software you run yourself is scored on its hosted or paid option if it has one. A free, self-hosted package with nothing to buy gets 20, 20 and 20 for the last three lines, and 0 to 40 for the first only if it ships a payment protocol.

## 4. Agent ergonomics, 60 out of 100, up to 6.5 more on the total

Why it scored 60: per_page (default 20), include for related objects and status and client filters, no field selection (15). page, per_page, sort, filter and status on index routes, plus bulk endpoints for actions across many ids (20). Laravel 422 validation errors name the field, but the docs only show the generic table (12). No idempotency keys. ?mark_sent=true and ?send_email=true are opt-in, so a plain create stays a draft (5). Official SDK in PHP only, Go from the community. Two headers on every call, X-API-TOKEN and X-Requested-With (8).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-ergonomics):

- 0 to 25, context cost. For MCP, the number and size of the tool definitions (25 for ten or fewer compact tools, 15 for 11 to 30, 5 for more than 30, plus up to 10 back for toolsets, dynamic loading or read-only subsets). For APIs, whether responses can be sized (field selection, limits, summaries).
- 20, pagination, filtering and output-size controls.
- 20, actionable, documented error responses, codes and messages an agent can recover from.
- 20, idempotency or safe retries, and for MCP the `readOnlyHint` and `destructiveHint` annotations.
- 15, sensible defaults, few required parameters, and official SDKs in at least two languages.

Models are read for tool use, structured output, prompt caching, context length, batch and SDKs. Frameworks for how much code and how many defaults a tool-calling agent with MCP needs.

## 5. Schema & documentation, 66 out of 100, up to 5.5 more on the total

Why it scored 66: OpenAPI 3 spec in the repository with 379 operations and a demo server, though its info version reads 5.12.55 while the app is at 5.13.43 (23). No llms.txt or Markdown docs (0). Path descriptions explain the chained query parameters and actions such as mark_sent, but rarely when to use one route over another (12). Typed schemas in the components, with allowed values often given in prose ("a comma separated list of invoice status strings") rather than enums (10). curl and PHP examples on each path and a generic status-code table (11). GitHub releases with notes, the API fixed at /api/v1, no API changelog of its own (10).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-schema):

APIs and MCP servers.

- 25, a machine-readable contract (a public OpenAPI file or similar; for MCP, typed JSON Schema inputs on every tool).
- 10, llms.txt or Markdown docs served for agents.
- 0 to 20, descriptions that say what a tool is for, when to use it and when not to, read from the tool definitions in the source or the API reference.
- 0 to 15, typed inputs with enums, constraints and required fields, and no free-form JSON blobs.
- 0 to 15, examples and documented error responses.
- 15, versioning and a public changelog.

Models are read from the API reference, the OpenAPI file, llms.txt, the structured-output and tool-use docs and the model cards. Frameworks from docs a model can follow, typed interfaces, examples and the API reference.

## 6. Transparency & trust, 65 out of 100, up to 3.1 more on the total

Made of editorial 54, provenance 75.

Why it scored 65: Source-available under the Elastic License 2.0, which is clear but isn't an OSI licence, so we scored between closed and open (20). Terms and privacy page both dated 14 February 2026, naming seven vendors and a DPA, but no retention periods and no address or governing law for Invoice Ninja LLC (15). No deprecation policy found, only release notes (3). Self-hosted error reporting is opt-in by checkbox and disclosed. Vendors named (Cloudflare, Linode, Google, Stripe, Postmark and others) without data locations (16).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-transparency):

- 0 to 30, source availability and licence clarity. 30 for open source under an OSI licence, 15 for closed with clear terms, 0 for unclear terms.
- 0 to 30, data handling and retention statements that agree with each other (privacy policy, DPA, retention periods, subprocessors).
- 0 to 20, a deprecation policy or notices with dates.
- 0 to 20, telemetry disclosed with an opt-out (local software), or subprocessors and data locations disclosed (hosted).

The other half of Transparency and trust is the provenance score, computed from checked facts (below). The category score is the mean of the two.

Provenance checks not met in full (half of this category, computed from checked facts):

- Endpoint on the vendor's domain: invoicing.co is not on invoiceninja.com (0 of 15)
- security.txt: not found (0 of 10)

## 7. Maintenance & community, 83 out of 100, up to 1.5 more on the total

Why it scored 83: v5.13.43 on 18 September 2026 (30). 16 tagged releases since 3 July (20). Pull requests merge within days on v5-stable. We couldn't see issue reply times from git (15). Official PHP SDK, last tagged v1.4.0 in January 2025 with commits in July 2026. No MCP server (8). PHPUnit CI across PHP 8.2 to 8.5 on every push to v5-stable and v5-develop, plus Dependabot (10).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-maintenance):

- 0 to 30, time since the last release, or the last published model or API change for a closed service. 30 within 30 days, 20 within 90, 10 within 180, 0 older.
- 20, at least three releases or dated changelog entries in the last 90 days.
- 0 to 25, responsiveness. Issues and pull requests answered on GitHub (the open issues and how recent the replies are). For closed services, a public changelog and a support or community channel that answers, 0 to 15.
- 15, presence in the official MCP registry under a verified namespace (MCP servers), or current official SDKs (APIs and models).
- 10, package health, current dependencies and CI.

Models are read for deprecation notice periods and model churn rather than release counts.

## Deductions

Each comes off the total. A fixed and documented problem counts for less at the next check.

- -1: two moderate stored XSS advisories published 22 and 23 March 2026, GHSA-98wm-cxpw-847p (invoice line items, CVSS 5.4, fixed in 5.13.4) and GHSA-xph7-9749-56mh (product notes). Fixed and disclosed in public, so the deduction is small (https://github.com/invoiceninja/invoiceninja/security/advisories)

## What we couldn't check

What we couldn't read counted as absent. Publishing it on a page a plain HTTP fetch can read (not only in a browser) lets the next check count it.

- Incident history for the last 90 days, since the status page shows seven days and /history returns 404
- Whether hosted Enterprise user permissions restrict what an API token can do
- Issue reply times on GitHub
- The white-label price wasn't on the pricing page we fetched, so $40 a year rests on the 30 September check

## Weaknesses

- No general ledger, journals or balance sheet, so the bookkeeping half of the category test can't be done
- Rate limits aren't in the docs, only in the source
- Status page shows seven days and has no history page
- No scoped or read-only API tokens
- Hosted Free plan excludes the REST API

## What costs an agent a turn today

The notes we give agents before they call it. Each one is a workaround an agent shouldn't need.

- Send X-Requested-With: XMLHttpRequest with X-API-TOKEN on every call
- Prototype against demo.invoiceninja.com with X-API-TOKEN: TOKEN before asking for real credentials
- 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
- Stay under 1,000 requests a minute per token on the hosted service and 20 a minute on report exports
- Record a supplier bill as an expense or purchase order. There's no bills resource

## What the review panel asked for

- turn prose lists into enums
- document 422 validation bodies
- read-only API tokens
- publish a security.txt

## When it's done

Send what changed and where it's published as a dispute (https://www.anchorterminal.com/builders/#disputes, or `POST https://www.anchorterminal.com/api/v1/contact` with `"kind": "dispute"`). Disputes are answered in public, and the listing is checked again by the same checklist. Paying for an audit or a listing claim changes nothing here.