How it works

Overview

When a licence number is submitted, SIA Checker queries the public register and normalises the result into a consistent JSON response, removing the need to deal directly with upstream instability or structural changes.

Upstream servers

Licence data is sourced from the gov.uk public register, operated by the Security Industry Authority.

Availability and response times depend on these upstream servers. To provide reliable access, SIA Checker applies caching and internal retries to reduce the impact of temporary issues.

Licence results are cached for 24 hours. Repeated requests for the same licence within this period return cached data and do not consume additional quota.

Request behaviour

Verification requests normally complete in under one second for fresh data and in milliseconds when cached.

Each request has a 5-second time budget. If processing takes longer, the connection is released with 202 Accepted and a PENDING status. This indicates that licence data is still being collected from the upstream server.

Retry the same request until results are returned. Retrying can be done at any pace.

If the upstream servers are temporarily unavailable, the API may return SERVICE_UNAVAILABLE. In this case, retry the request later – results will be returned once the upstream service is healthy again.

Upstream errors

In rare cases, licence data cannot be extracted due to upstream changes. When this happens, the API returns PARSE_ERROR.

Please report such cases to help@siachecker.co.uk so they can be investigated.