API reference

ZerraLedger REST API

REST, JSON, OpenAPI 3.1. Built for direct integration into carbon accounting platforms, corporate travel systems, and ERP sustainability modules. No proprietary SDKs required.

Base URL https://api.zerraledger.com/v1

Authentication

All requests require a Bearer token in the Authorization header. Tokens are issued per-organisation during sandbox onboarding. Request access →

Provenance guarantee: Every certificate reference returned by the API is timestamped against source registry data at ingestion. No derived or estimated values enter the pipeline. The full audit trail — from API response back to the government-issued certificate — is available on every request via the provenance object.

GET /certificates

Returns a paginated list of SAF certificates ingested from supported registries. Filter by scheme, vintage period, fuel pathway, or issuing authority.

Parameter	Type	Required	Description
scheme	string	Optional	Filter by scheme code: `AU_GO`, `CORSIA`, `EU_REFUELEU`, `UK_SAF`, `SG_CAAS`
period	string	Optional	Vintage period, e.g. `2025-Q4` or `2025`
pathway	string	Optional	Fuel pathway code (HEFA, AtJ, PtL, etc.)
limit	integer	Optional	Page size, max 100. Default 20.
cursor	string	Optional	Pagination cursor from previous response

GET /certificates/{id}

Returns full detail for a single SAF certificate, including provenance metadata, fuel pathway attributes, issuing authority, and scheme-specific fields.

Parameter	Type	Required	Description
id	string	Required	ZerraLedger certificate ID (e.g. `AU-GO-2025-04821`)

POST /certificates/reconcile

The core reconciliation endpoint. Maps SAF certificates from a given scheme against a compliance obligation, returning coverage percentage, gap in CO₂ tonnes, certificate references, and eligibility flags. The primary integration point for carbon accounting platforms and travel systems.

Parameter	Type	Required	Description
scheme	string	Required	Source certificate scheme: `AU_GO`, `CORSIA`, etc.
obligation	string	Required	Target obligation scheme: `CORSIA`, `EU_REFUELEU`, etc.
route	string	Required	IATA route pair, e.g. `SYD-LHR`
period	string	Required	Reporting period, e.g. `2025-Q4`
volume_tonnes	number	Optional	Total SAF volume to reconcile against. If omitted, derived from route uplift data.

Response — 200 OK

{
  "status": "reconciled",
  "certificate_id": "AU-GO-2025-04821",
  "coverage_pct": 87.4,
  "gap_tonnes_co2": 12.6,
  "scheme_verified": true,
  "double_count_flag": false,
  "provenance": {
    "source": "CER_GO_REGISTRY",
    "ingested_at": "2025-10-14T03:12:44Z"
  }
}

GET /schemes

Returns all supported SAF schemes with their current status, coverage regions, certificate types, and reporting period conventions.

GET /schemes/{code}/eligibility

Returns fuel pathway eligibility rules for a specific scheme — which production pathways (HEFA, AtJ, PtL, etc.) are eligible, volume limits, co-processing restrictions, and any scheme-specific constraints.

Parameter	Type	Required	Description
code	string	Required	Scheme code: `AU_GO`, `CORSIA`, `EU_REFUELEU`, `UK_SAF`, `SG_CAAS`

POST /obligations/check

Checks compliance status for a given operator, period, and obligation scheme. Returns overall compliance status, shortfall volumes, and recommended certificate sourcing actions.

Parameter	Type	Required	Description
operator_icao	string	Required	ICAO airline designator code
obligation	string	Required	Obligation scheme code
period	string	Required	Reporting period

GET /routes/{iata}/exposure

Returns Scope 3 SAF obligation exposure for a given route pair — which schemes apply, estimated SAF volumes required per period, and available certificate pools from each applicable jurisdiction.

Parameter	Type	Required	Description
iata	string	Required	IATA route pair, e.g. `SYD-LHR`
period	string	Optional	Reporting period. Defaults to current quarter.

OpenAPI 3.1 specification and sandbox access available on request.

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