specification: API Commons Rate Limits
specificationVersion: '0.1'
provider: Scottish and Southern Electricity Networks
providerId: ssen
generated: '2026-07-27'
method: probed
created: '2026-07-27'
modified: '2026-07-27'
source: >-
  Live response headers observed on
  https://ssentransmission.opendatasoft.com/api/explore/v2.1/catalog/datasets on
  2026-07-27, plus the 429 quota response schema declared in
  openapi/ssen-transmission-opendatasoft-explore-v2.1-openapi.json.
description: >-
  Only one of SSEN's four public APIs signals rate limits in a machine-readable
  way: the Transmission Open Data Explore API, which runs on the Opendatasoft
  platform and returns X-RateLimit-* headers on every response and an RFC-style
  quota body on 429. The observed anonymous allowance was 100 calls with a daily
  reset window. The CKAN Distribution Action API, the Power Track outage API and
  NeRDA publish no rate-limit headers and no documented quota.
tags:
  - Rate Limiting
  - Open Data
  - Electricity
sources:
  - https://ssentransmission.opendatasoft.com/api/explore/v2.1/catalog/datasets
  - openapi/ssen-transmission-opendatasoft-explore-v2.1-openapi.json
headers:
  limit: X-RateLimit-Limit
  remaining: X-RateLimit-Remaining
  reset: X-RateLimit-Reset
  datasetLimit: X-RateLimit-dataset-Limit
  datasetRemaining: X-RateLimit-dataset-Remaining
  datasetReset: X-RateLimit-dataset-Reset
  deprecation: ODS-Explore-API-Deprecation
responseCodes:
  throttled: 429
throttleResponse:
  contentType: application/json; charset=utf-8
  fields: [errorcode, error, call_limit, limit_time_unit, reset_time]
  example:
    errorcode: 10002
    limit_time_unit: day
    call_limit: 10000
    reset_time: '2021-01-26T00:00:00Z'
  note: >-
    Example values above are the ones published verbatim in the OpenAPI 429
    response example; the live allowance observed on the SSEN portal differs
    (see limits[]).
limits:
  - name: Anonymous Explore API calls (SSEN Transmission portal)
    api: SSEN Transmission Open Data Explore API
    scope: client
    metric: requests_per_day
    limit: 100
    timeFrame: day
    observed: '2026-07-27'
    evidence: 'X-RateLimit-Limit: 100, X-RateLimit-Remaining: 94, X-RateLimit-Reset: 2026-07-28 00:00:00+00:00'
    note: >-
      Reset is an absolute UTC midnight timestamp, so the window is a calendar
      day. A per-dataset counter is exposed separately via the
      X-RateLimit-dataset-* headers.
payload_limits:
  - endpoint: /catalog/datasets/{dataset_id}/records
    constraint: returns a limited number of records per call (paginate with limit/offset)
    workaround: use the /exports endpoints, which the spec states have no such limitation
unmetered_or_undocumented:
  - api: SSEN Distribution Data Portal API (CKAN)
    rate_limit_headers: none observed
    documented_quota: none published
  - api: SSEN Power Track Real Time Outage API
    rate_limit_headers: none observed
    documented_quota: none published
  - api: SSEN NeRDA API
    rate_limit_headers: not testable anonymously (API key required)
    documented_quota: none published in the NeRDA API Guide