E-Rechnung API (XRechnung & ZUGFeRD Validator)

The E‑Rechnung API provides a REST endpoint for validating German XRechnung (CII/UBL) and ZUGFeRD invoices against the official KoSIT Schematron rules. Users can POST an invoice file or PDF and receive JSON indicating validity, detected format, and detailed rule violations with IDs and German explanations. The service offers 50 free validations per month via an API key, with optional paid plans for higher volume.

E-Rechnung API (XRechnung & ZUGFeRD Validator) is listed with 1 API on the APIs.io network. Tagged areas include Company, Validation, German, Invoicing, and XRechnung.

The E-Rechnung API (XRechnung & ZUGFeRD Validator) catalog on APIs.io includes 1 Spectral governance ruleset.

E-Rechnung API (XRechnung & ZUGFeRD Validator)’s developer surface includes documentation and 7 more developer resources.

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8.8/100 minimal ▬ flat Agent 2/100 human only Full breakdown ↓
scored 2026-11-13 · rubric v0.28.0 · Show this score on your site →

1 API

Company Validation German Invoicing XRechnung ZUGFeRD

Kin Score

Kin Score How this is scored →
scored 2026-11-13 · rubric v0.28.0

Composite quality — 8.8/100 · minimal

Contract Quality 0.0 / 21

Developer Ergonomics 1.6 / 17

Access Clarity 0.0 / 17

Operational Transparency 0.0 / 11

Contract Governance 1.9 / 10

Discoverability 5.3 / 9

Regulatory Posture 0.7 / 15

Agent readiness — 2/100 · human only

Machine-Readable Contract 0 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Pagination 5 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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Agent readiness — checks not met, largest first (exact, from this profile):

Machine-Readable Contract +18 pts — api_specs includes an OpenAPI document Ask about this →
MCP Server +12 pts — deployment.mode + probe verdict on the mcp/ manifest, not the pointer; an unprobed slug falls back to authorship Ask about this →
Machine-Readable Auth +10 pts — a served openid-configuration/oauth-authorization-server carrying `issuer` (served), else the securitySchemes class in the provider OpenAPIs — bound (mutualTLS, DPoP, Signature) > negotiable (oauth2 authorizationCode/clientCredentials, openIdConnect) > bearer (http bearer, apiKey) Ask about this →
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented) Ask about this →
Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes Ask about this →
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0 Ask about this →

12 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Contract Quality scores 0.0 — up to +25.0 composite points Ask about this →
Access Clarity scores 0.0 — up to +20.0 composite points Ask about this →
Developer Ergonomics scores 9.5 — up to +18.1 composite points Ask about this →

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

Not sure how this applies to your stack? Ask about any one item. Kin Lane reads every question, looks at your profile and your situation, and replies with what a fix would take — scoped to that one area, priced up front, yours whether you ship it or not. Ask a question →

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from the provider profile at artifacts.apis.io/erechnung-konverter/apis.yml: open an issue on github.com/api-evangelist/erechnung-konverter to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 1

Individual APIs this provider publishes, each with its own machine-readable definition.

E-Rechnung API

Validate German XRechnung and ZUGFeRD invoices via REST.

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs. Counts are the severity each rule declares, not results of running them.

E-Rechnung API (XRechnung & ZUGFeRD Validator) API Rules

8 rules · 6 error-severity 1 warn-severity 1 info-severity

SPECTRAL

Security Posture 1

Authentication, domain security, vulnerability disclosure, and trust-center signals.

E-Rechnung API (XRechnung & ZUGFeRD Validator) Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access (API Evangelist recommendations) 1

Recommended x-agentic-access execution contracts for AI agents.

E-Rechnung API (XRechnung & ZUGFeRD Validator) Agentic Access

2 operations · 2 acting

AGENTIC

Resources

Documentation 1

Reference material describing how the API behaves

Documentation

Documentation

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

Design & Contract 2

Pagination, idempotency, versioning, errors, and events

Spectral

Spectral

Conformance

Conformance

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Company 1

The organization behind the API

Website

Website

Other 2

Properties that don't map to a standard resource type

Hosts

Hosts

Vendors

Vendors

Source (apis.yml)

aid: erechnung-konverter
name: E-Rechnung API (XRechnung & ZUGFeRD Validator)
description: The E‑Rechnung API provides a REST endpoint for validating German XRechnung (CII/UBL) and ZUGFeRD invoices against
  the official KoSIT Schematron rules. Users can POST an invoice file or PDF and receive JSON indicating validity, detected
  format, and detailed rule violations with IDs and German explanations. The service offers 50 free validations per month
  via an API key, with optional paid plans for higher volume.
url: https://raw.githubusercontent.com/api-evangelist/erechnung-konverter/refs/heads/main/apis.yml
x-type: company
x-source: harvest:new-submission
x-tier: profiled
x-tier-reason: enrichment pass 2026-10-20 (modular-v1; was harvest)
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source:
  - security
  generated: '2026-11-13'
  method: derived
specificationVersion: '0.20'
created: '2026-10-20'
modified: '2026-10-20'
tags:
- Company
- Validation
- German
- Invoicing
- XRechnung
- ZUGFeRD
tags_raw:
- Company
- API
- Validation
- German
- Invoicing
- XRechnung
- ZUGFeRD
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: AgenticAccess
  url: agentic-access/erechnung-konverter-agentic-access.yml
- type: Spectral
  url: rules/erechnung-konverter-rules.yml
- type: Conformance
  url: conformance/erechnung-konverter-conformance.yml
- type: Hosts
  url: hosts/erechnung-konverter-hosts.yml
- type: Vendors
  url: vendors/erechnung-konverter-vendors.yml
- type: DomainSecurity
  url: security/erechnung-konverter-domain-security.yml
- type: Website
  url: https://erechnung-konverter.vercel.app
- type: Documentation
  url: https://erechnung-konverter.vercel.app/e-rechnung-api
apis:
- name: E-Rechnung API
  description: Validate German XRechnung and ZUGFeRD invoices via REST.
  humanURL: https://erechnung-konverter.vercel.app/e-rechnung-api
  baseURL: https://erechnung-konverter.vercel.app
  aid: erechnung-konverter:e-rechnung-api
x-submission-notes: Free REST API validating XRechnung/ZUGFeRD e-invoices against KoSIT Schematron; API key; 50 free/month.
x-submission-probe: root 200; docs 200 (68KB); openapi.json 200 OpenAPI 3.1.0, 2 paths, server on own vercel host; soft-404
  404 (clean).
x-enrichment:
  date: '2026-10-20'
  status: enriched
  artifacts_added: 11
  pass: modular-v1
  engine: identity=local,contract=local,surfaces=local,docs=local,regulatory=local

E-Rechnung API (XRechnung & ZUGFeRD Validator) — frequently asked questions

Does E-Rechnung API (XRechnung & ZUGFeRD Validator) have an API?

Yes. APIs.io lists 1 API from E-Rechnung API (XRechnung & ZUGFeRD Validator), including E-Rechnung API.

Is the E-Rechnung API (XRechnung & ZUGFeRD Validator) ready for AI agents?

E-Rechnung API (XRechnung & ZUGFeRD Validator) has a Kin Score of 8.8 out of 100 (minimal) and an Agent Readiness score of 1.8 (human-only), scored by API Evangelist on 2026-11-13.

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