Methodology: how we identify Peppol Access Point providers
1. SML DNS lookup (every participant)
Every Peppol participant is discoverable through the official Peppol Service Metadata Locator (SML), a public DNS system operated by the European Commission. We compute each participant's SML hostname (a Base32-encoded SHA-256 hash of the participant identifier) and query its NAPTR record, which points to the SMP server operated by the participant's service provider. This is the same lookup every Access Point performs to deliver a document.
2. SMP metadata for shared/national SMPs
For most participants the SMP host uniquely identifies the provider. But some countries run a centralised national SMP (e.g. Norway's ELMA) shared by many providers, and some SMP hosts are multi-tenant aggregators. There, the hostname is not enough, so we fetch the participant's SMP metadata over HTTPS and read the AS4 endpoint URL and the Access Point certificate. The certificate subject contains the provider's legal name and its unique Peppol Access Point seat ID — the most authoritative provider signal available.
3. Classification & caching
Unique SMP hosts number in the low hundreds, so we maintain a curated map from SMP host / endpoint domain / certificate to the provider's business name. Participants are then classified against this map. New unknown hosts are flagged automatically and added manually.
Limitations
- White-label SMP platforms may host several service providers; counts then reflect the platform operator, not the reseller.
- A participant that has left the network no longer resolves in SML and is excluded.
- Growth charts count new participant registrations attributed to the provider they currently use; provider migrations can shift historical figures.
- All data comes from public Peppol infrastructure (SML DNS and SMP endpoints). No private or commercial data source is used.
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