When your users start asking for e-invoicing, your product needs four capabilities: producing invoices conformant with the European standard EN 16931, delivering them over the network buyers use (in Europe primarily Peppol), validating documents before they go out, and optionally receiving documents for your users. The question is no longer "whether": in Estonia EN 16931 has been the primary e-invoice format since 1 July 2025 with registered buyers entitled to demand e-invoices, and Baltic B2B mandates are landing through 2028. Your options are two: become a certified Access Point yourself, or consume one through its API.
What does building it yourself actually mean?
Becoming a certified Access Point is a compliance project, not a feature ticket: OpenPeppol membership, certification, operating AS4 messaging infrastructure, running an SMP for participant management, and tracking rule-set updates on the network's release cycle. It is the right path when e-invoicing infrastructure is your product. When e-invoicing is one feature among many, this path costs quarters of engineering before the first user sees value.
What does consuming an API mean?
An integration project: your application POSTs invoice data to a certified provider's API, gets synchronous validation with actionable errors, delivery status via webhooks, and participant management as API operations. Accreditation, transport and rule maintenance stay with the provider. The timeline is a different world – with a documented API, a first test document within one working day is realistic, and production readiness is measured in weeks. The technical layers (formats, validation, statuses) are covered in our developer guides to sending e-invoices via API gift generating UBL invoices.
How to decide: three questions
First: is e-invoicing your product's core or a supporting feature? Core justifies owning infrastructure; support does not. Second: how many markets must you cover? Every country adds rules. Latvia's B2B mandate lands in 2028, Lithuania's public sector ingests via Peppol: and an API provider absorbs that variety for you. Third: who is on call at night? An Access Point is infrastructure whose outage stops your users' cash flow; ask honestly whether you want it on your pager rota.
The provider checklist
Certified Access Point status. Synchronous validation with structured errors. A sandbox with separate keys. Signed, idempotent webhooks. Participant registration and migration as API operations rather than support tickets. And documentation your developer never has to call support about: that last one predicts the quality of everything else.