API/Participants

Look up a Peppol participant

GET/v1/participants/{participant_id}· API key

Answers "can this business receive Peppol invoices, and which documents does it accept?" by querying the Peppol SML and the participant's SMP live. The SML is the authoritative source; the Peppol Directory is optional for participants, so directory is null for many businesses that are nonetheless registered.

A participant that is not registered returns 200 with registered: false — absence from the network is an answer, not a missing resource.

For a UK business, the participant identifier is usually its VAT number under scheme 9932. Registrations exist both with and without the GB prefix, and Peppol treats them as different participants. So for 9932 both forms are tried, and id reports the one that is registered. Identifier values are case-insensitive; id is returned lower-cased, as Peppol hashes it.

The lookup follows the Peppol SML specification (v1.3.0, in force since November 2025): a U-NAPTR record at a base32 SHA-256 hash of the identifier, then the participant's SMP. Results are cached for up to five minutes; checked_at says when the network was last asked.

Request

curl https://api.einvoicing.dev/v1/participants/<participant_id> \  -H "Authorization: Bearer $EINVOICING_API_KEY"

<?php$client = new GuzzleHttp\Client();$response = $client->request('GET', 'https://api.einvoicing.dev/v1/participants/<participant_id>', [    'headers' => [        'Authorization' => 'Bearer ' . getenv('EINVOICING_API_KEY'),    ],]);$data = json_decode((string) $response->getBody(), true)['data'];

req, _ := http.NewRequest(http.MethodGet, "https://api.einvoicing.dev/v1/participants/<participant_id>", nil)req.Header.Set("Authorization", "Bearer "+os.Getenv("EINVOICING_API_KEY"))res, err := http.DefaultClient.Do(req)if err != nil {	log.Fatal(err)}defer res.Body.Close()

const res = await fetch("https://api.einvoicing.dev/v1/participants/<participant_id>", {  headers: {    Authorization: `Bearer ${process.env.EINVOICING_API_KEY}`,  },});const { data } = await res.json();

Parameters

Name	In	Type	Description
`participant_id`required	path	string	A Peppol participant identifier as `scheme:identifier`, where `scheme` is a four-digit EAS code. URL-encode the colon if your client requires it (`%3A`); both forms are accepted.

Response

200

The network was asked and answered.

Field	Type	Description
`data`required	Participant	What the Peppol network says about one participant identifier.

Example responseapplication/json

{  "data": {    "id": "9932:GB123456789",    "scheme": "9932",    "identifier": "GB123456789",    "registered": true,    "capabilities": [      {        "name": "Peppol BIS Billing 3.0 Invoice",        "document_type_id": "urn:oasis:names:specification:ubl:schema:xsd:Invoice-2::Invoice##urn:cen.eu:en16931:2017#compliant#urn:fdc:peppol.eu:2017:poacc:billing:3.0::2.1",        "process_id": "urn:fdc:peppol.eu:2017:poacc:billing:01:1.0"      },      {        "name": "Peppol BIS Billing 3.0 Credit Note",        "document_type_id": "urn:oasis:names:specification:ubl:schema:xsd:CreditNote-2::CreditNote##urn:cen.eu:en16931:2017#compliant#urn:fdc:peppol.eu:2017:poacc:billing:3.0::2.1",        "process_id": "urn:fdc:peppol.eu:2017:poacc:billing:01:1.0"      }    ],    "directory": {      "name": "Acme Widgets Ltd",      "country_code": "GB"    },    "checked_at": "2026-09-11T14:03:11.482Z"  }}

Errors

Every error is application/problem+json (RFC 9457). Branch on type, which is stable, never on title or detail.

Status	When
401	No key, or a key that is unknown or revoked. Problem `type` is `unauthenticated`. /problems/unauthenticated
402	The Free plan's monthly allowance for this operation is used up. This is a billing state, not a rate limit: waiting will not help until the period resets or the plan changes. Paid plans never receive it. Problem `type` is `allowance-exhausted`. /problems/allowance-exhausted
422	The identifier is not in `scheme:identifier` form with a four-digit EAS scheme. Problem `type` is `invalid-participant-id`. A well-formed identifier under a scheme nobody uses is not an error: it answers `200` with `registered: false`.
429	Too many requests in a short window. Slow down and retry after the number of seconds in `Retry-After`. Problem `type` is `rate-limited`. /problems/rate-limited
502	The Peppol SML or the participant's SMP did not answer in time. The question is still open, not answered "no". Problem `type` is `upstream-unavailable`.

Schemas

Participant

What the Peppol network says about one participant identifier.

Field	Type	Description
`id`required	string	The identifier as looked up, `scheme:identifier`.
`scheme`required	string	EAS scheme code.
`identifier`required	string
`registered`required	boolean	True when the SML resolves the participant to an SMP.
`capabilities`required	object[]	The e-invoicing document types the participant accepts: Peppol BIS Billing 3.0 and PINT Billing invoices and credit notes. Other registered types (orders, catalogues and so on) are not listed. Empty when not registered, or when the participant's SMP no longer knows it.
`name`required	string	A readable name for the document type.
`document_type_id`required	string	The Peppol document type identifier, as registered in the SMP.
`process_id`required	string	The Peppol process identifier.
`directory`required	object or null	The participant's Peppol Directory entry, when it has chosen to publish one.
`name`	string or null
`country_code`	string or null
`checked_at`required	Timestamp · date-time	RFC 3339, UTC, millisecond precision.