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E-invoice validation

Validate.
Understand. Fix.

Check Peppol, XRechnung and ZUGFeRD / Factur-X invoices against EN 16931 and each format's official rules. Find the failure, understand the rule and fix the source document.

Try the Peppol validator Generate Peppol UBL from JSON

Other formats: XRechnung or ZUGFeRD / Factur-X. View plansNo account needed to try it. Anonymous documents and results are not kept.

Ironfang Finance / validation resultExample output

invoice.xml

UBL Invoice / validation completed

Invalid
XML syntaxPassed
UBL schemaPassed
EN 169311 finding
Peppol rulesPassed

BR-CO-10

Line amounts do not add up

The document-level line total must match the sum of the individual line net amounts.

Read the rule explanation
Peppol BIS Billing 3Transient XML checks

Document validation

From your document to a clear result.

Every format is checked the same way: one result brings the document checks and rule findings together, names the ruleset that checked it, and tells an invalid document apart from a service failure.

Invoices and credit notes

Check Peppol BIS Billing 3 in UBL, XRechnung in UBL or CII, and ZUGFeRD / Factur-X as a hybrid PDF or its XML. Use the free browser tools or send a request from your application.

Every validation layer

See each layer separately: the XML and its schema, the format's business rules and, for a hybrid PDF, the PDF/A and attachment checks. Distinguish an invalid document from a validation service failure.

Findings you can act on

Read the rule identifier and finding, then follow a reviewed explanation where available. Fix the source document and validate it again.

Results you can keep

Signed-in and API results are saved for 30 days, with the option to delete them sooner. Download the JSON, or turn a retained result into a signed report anyone can verify.

Your first validation

From a finding to a fix.

  1. Choose your document

    Open the validator for your format and try its sample, or upload your own invoice or credit note: XML, or a hybrid PDF for ZUGFeRD / Factur-X. No account needed.

  2. Read the findings

    Follow the verdict through each validation layer. Open the available rule explanations to understand what needs to change.

  3. Fix and validate again

    Update your source document and validate it again. Keep the result, or bring the same check into your application through the API.

Open the Peppol validator

Other formats: XRechnung or ZUGFeRD / Factur-X.

Try anonymously

New to e-invoicing? Explore the e-invoicing learning hub

Build with Ironfang Finance

  • API keys and saved validation history
  • Jobs, batches and webhooks
  • S3-compatible artifact delivery
  • SDKs, CLI and automation tooling

Try Ironfang Finance without an account. Create one when you're ready to integrate it. Free includes 250 validations each month; account generation requires a paid plan.

Create free account

Rule explanations

Understand what went wrong.

Start with the rule, follow its meaning and work back to your document. Explanations come from the same reviewed catalogue as the validator.

Browse the validation guide

BR-01

The specification identifier is missing

Invoice and CreditNote documents need a non-empty CustomizationID identifying their specification.

BR-CO-10

Line amounts do not add up

The document-level line total must match the sum of the individual line net amounts.

PEPPOL-EN16931-R004

Check the billing specification identifier

This rule checks the Peppol Billing identifier prefix and rejects a double-colon sequence in the identifier.

Other rules retain their engine finding and identifier. Explanations are shown where reviewed guidance is available. Browse all 142 rule explanations.

Developer workflow

Make validation part of your application.

Send an invoice's XML, or a ZUGFeRD / Factur-X PDF, over HTTPS and receive structured results. List saved validations, read their findings and delete results through the same API.

Use the published Python or TypeScript validation SDK, Python CLI or GitHub Action. For durable work, configure signed webhooks and S3-compatible artifact delivery with independent retries. Delivery to your endpoint or bucket does not send an invoice over Peppol.

Read the API quickstart OpenAPI contract

Integration examples for your account are in the portal.

Ironfang Finance / API workflow

Required key scope:finance:einvoices:write

Request

curl --request POST \
  'https://api.ironfang.com/finance/v1/einvoices/validate' \
  --header 'Authorization: Bearer YOUR_API_KEY' \
  --header 'Content-Type: application/xml' \
  --header 'Accept: application/json' \
  --header 'Idempotency-Key: invoice-2026-001' \
  --data-binary '@invoice.xml'

Example response - excerpt

200 OK
Content-Type: application/json

{
  "operation_id": "019f29a4-3158-7b81-8f64-f1072146de30",
  "status": "completed",
  "outcome": "valid",
  "ruleset": {
    "id": "fwrs_example_invoice_2026a"
  },
  "findings": [],
  "findings_summary": {
    "returned": 0, "total": 0,
    "cap": 1000, "truncated": false
  }
}

Send your XML file as the request body. The optional Idempotency-Key lets you retry the same request without a second validation or charge. Invalid documents also return 200, with outcome: invalid and their findings. XRechnung and ZUGFeRD / Factur-X use the V2 route; see the API quickstart.

Illustrative responses. Authenticated results are saved for 30 days. Synchronous validation does not retain uploaded XML.

Pricing

Start free. Choose your document allowance.

Validate on Free, or subscribe to generate invoices and handle more documents. Fixed monthly prices in GBP, including applicable tax. No automatic overage charges.

Free

£0/ month

250 validations / month

  • Validate documents
  • Saved results and API access
  • No card required
Start free

Build

£29/ month

5,000 operations / month

  • Validate and generate documents
  • Saved results and API access
  • One shared document allowance
Start with Build

Pro

£99/ month

25,000 operations / month

  • Validate and generate documents
  • Saved results and API access
  • One shared document allowance
Start with Pro

Platform

£299/ month

100,000 operations / month

  • Validate and generate documents
  • Saved results and API access
  • One shared document allowance
Start with Platform

How your allowance works

One completed validation counts, including a result that finds invoice errors. One successful generation counts once. Downloads and idempotent retries add no usage. Malformed requests and service failures do not use your allowance; unfinished work reserves it.

Free resets each UTC calendar month. Paid allowances follow your monthly subscription period. Account-based generation requires a paid plan. The anonymous validator and JSON playground remain free with request and rate limits.

For UK and EU businesses

Paid plans are available to businesses and sole traders established in the UK or EU. UK businesses do not need a VAT number. EU automatic checkout requires a verified VAT number and matching business details. EU businesses without a VAT number, or with verified details that need review, must be approved before paying.

Enter your business details and request any required review in the billing portal. You choose your subscription explicitly. Manage plan changes and cancellation there too; Ironfang Finance has separate payment details and invoice history.

See our terms and refund policy. Document validation and generation do not send invoices over Peppol or certify legal or tax compliance.

Questions

Know what your result means.

Do I need an account to try it?
No. The free Peppol, XRechnung and ZUGFeRD / Factur-X validators accept a sample or your own document without an account. Create an account when you want saved validation history and API integration.
When do I need a paid plan?
Free accounts include 250 validations per UTC calendar month. Choose Build, Pro or Platform to generate Peppol BIS Billing 3 documents through your account or increase your allowance. Anonymous browser tools remain free with request and rate limits.
Will I be charged if I reach my allowance?
There are no automatic overage charges. New account operations stop at the allowance until capacity is released, the period renews or you upgrade. Existing results stay available within their retention period. Subscriptions renew monthly until cancelled.
What happens to my invoice?
Synchronous validation does not retain the uploaded document. Anonymous results are transient; authenticated result JSON and findings are retained for 30 days and can be deleted sooner. Durable API jobs, when enabled, temporarily retain encrypted input until completion, cancellation or 24-hour expiry cleanup.
Can I download the result?
Yes. The Peppol validator downloads JSON and an unsigned readable report you can print or save as a PDF from your browser. Through the API, any retained result can be issued as a signed report. Downloaded copies stay under your control.
Does a passing result send or certify my invoice?
No. Validation checks supported structured-document rules. It does not send invoices over Peppol, establish participant registration or certify legal or tax compliance.
Read more about saved results and privacy Verify a signed report

Less to operate. More to ship.

Start with one document.

Try the sample, understand the findings and bring validation into your workflow.

Try the Peppol validator Create a free account

No card required for a Free account. Start with 250 validations per UTC calendar month and upgrade when you need more.