At some point in every B2B SaaS project, someone asks: "can we skip tax for EU business customers?". And then you spend a friday afternoon finding out... yes, you can, but you need to validate their VAT numbers first. And that opens a whole thing.

This is what I found, from my experience with VAT number in our global SaaS service.

Option 1: VIES directly

"VIES" is the official EU VAT database. It's run by the European Commission and it's free to use! Those are the good parts.

The bad is that it's a SOAP API from around 2003 and it really shows... You write raw XML, send over HTTP, and parse XML back. Error states come back as HTTP 200:s with fault codes buried in the body. Some member countries return full company names. Others return nothing. Germany is known for returning MS_UNAVAILABLE during regular business hours for no obvious reason.

Here's a minimal request:

curl -s https://ec.europa.eu/taxation_customs/vies/services/checkVatService \
 -H "Content-Type: text/xml" \
 -d '<?xml version="1.0" encoding="UTF-8"?>
<soapenv:Envelope
 xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
 xmlns:urn="urn:ec.europa.eu:taxud:vies:services:checkVat:types">
 <soapenv:Body>
 <urn:checkVat>
 <urn:countryCode>SE</urn:countryCode>
 <urn:vatNumber>556543123401</urn:vatNumber>
 </urn:checkVat>
 </soapenv:Body>
</soapenv:Envelope>'

It works. Just budget time for XML parsing, error handling, and tests for the unavailable-state edge cases.

Pros: free, no rate limits, no third party in the chain
Cons: XML, inconsistent responses per country, no UK support (post-Brexit), needs defensive error handling

Option 2: VatLayer / Abstract API / Vatstack

A bunch of services wrap VIES in a REST API, which solves the XML problem. The docs are good and the responses are consistent.

The catch is that most charge from the very first request. No real free tier. If you're running validations in development and staging too, costs add up before you've even shipped. I also noticed one service routing all lookups through a single US region, which adds unnecessary latency and possible compliance issue for European customers.

Pros: clean REST API, no XML
Cons: cost starts from day one, EU-only coverage on most plans

Option 3: TaxVett

TaxVett is what I ended up using lately. Free lookups every month, no credit card needed, and it covers not just EU but also UK. And for the future there's also Norway, Australia and Singapore in the same API. For our service with companies globally that's is very useful.

The request is simple:

curl -X POST https://api.taxvett.com/v1/validate \
 -H "X-Api-Key: YOUR_KEY" \
 -H "Content-Type: application/json" \
 -d '{"number": "SE556543123401"}'

Response:

{"valid":true,"number":"SE556543123401","country":"SE","regime":"eu_vat","verification_method":"live_registry","company_name":"Acme AB","company_address":"Stockholm, Sweden"}

Country is auto-detected from the number prefix, so you don't need to pass it unless the format is ambiguous. If VIES is unavailable for a specific country, you get a proper error back in the same JSON shape rather than a silent success.

For UK numbers, it routes to HMRC instead of VIES. There's a separate post on UK VAT validation here if you need that specifically.

Pros: free to start, REST API, consistent response across all countries, covers UK/AU/NO/SG too
Cons: third-party dependency, paid plans kick in at higher volumes (from 9 EUR/month)

How do I integrated in Node.js?

async function validateVatNumber(vatNumber: string): Promise<{
 valid: boolean;
 companyName?: string;
}> {
 const response = await fetch("https://api.taxvett.com/v1/validate", {
 method: "POST",
 headers: {
 "X-Api-Key": process.env.TAXVETT_API_KEY!,
 "Content-Type": "application/json",
 },
 body: JSON.stringify({ number: vatNumber }),
 });

 if (!response.ok) {
 // 422 = format invalid, 404 = not found in registry
 return { valid: false };
 }

 const data = await response.json();
 return {
 valid: data.valid,
 companyName: data.company_name,
 };
}

When valid is true, I also prefill the company name in the checkout form. Saves the customer a step and feels polished.

The batch endpoint?

If you need to validate existing customers in bulk, there's also a batch endpoint:

curl -X POST https://api.taxvett.com/v1/validate/batch \
 -H "X-Api-Key: YOUR_KEY" \
 -H "Content-Type: application/json" \
 -d '{
 "numbers": [
 {"number": "SE556543123401"},
 {"number": "DE123456789"},
 {"number": "FR12345678901"}
 ]
 }'

I batch 50 per request. Each one counts against your quota separately, which matters if you're on the free plan.

What to pick?

If you're EU-only and happy with XML and error handling: VIES directly is totally fine and free.

If you want a clean API and are selling into multiple regions: a wrapper is worth it! TaxVett is the only one I found with a real free tier, that made it easy to evaluate without committing.