Designing and delivering the COVID Pass API to deliver urgent access for 20 million people
- National-scale delivery
- Architecture
- Inclusive design
Executive summary
National digital services must operate at pace, under scrutiny and at population scale, while remaining accessible, secure and aligned to public policy. When services underpin public trust, failure is not an option.
This case study shows how investing in strong architecture, inclusive design and delivery discipline enables government services to adapt rapidly to policy change while maintaining reliability. The same principles apply across regulated environments where national-scale delivery depends on resilience, accessibility and confidence in execution.
The problem we solved
NHSX was tasked by the Department of Health and Social Care with delivering the COVID Pass API for use by citizens across the UK.
At the outset of the COVID certification programme, the proposed solution relied on a proprietary application programming interface that did not fully align with government technology and service standards. There was an urgent need to deliver a national digital service that could operate at scale, meet accessibility requirements and adapt quickly to evolving policy, all under intense public and political scrutiny.
In parallel, an inclusive letter service had been delivered by a third party but was not meeting requirements. NHSX needed a partner who could stabilise delivery, redesign the service and ensure it could support a rapidly changing policy landscape without compromising reliability or trust.
What we did
Answer Digital partnered with NHSX to lead the design and delivery of the COVID Pass API and Letter Service.
We took over responsibility for the inclusive letter service, providing architectural leadership and rebuilding the solution to meet national standards for availability, security and accessibility. Working closely with policy, service design and delivery teams, we shaped the end-to-end user journey and identified opportunities to improve how citizens accessed COVID certification.
Delivery was structured to support rapid iteration and frequent policy change, with repeatable deployment and strong quality controls built into the process. We aligned delivery to the Government Digital Service Standard and used early prototyping, controlled trials and phased releases to de-risk complex features and gather user feedback before scaling nationally.
The long-term impact
The COVID Pass service was successfully delivered and transitioned within 16 weeks, exceeding service level agreements and supporting over 100,000 citizens per week requesting letters at peak demand.
The service adapted to ongoing policy changes, including eligibility rules, age thresholds, overseas vaccinations, boosters and devolved administration requirements. It passed Government Digital Service assessment and received international recognition for its delivery.
The programme introduced antifraud measures through barcode verification, simplified policy management through centralised rules integration and improved service efficiency through an event-driven approach.
Answer Digital’s work was recognised with the Digital Leaders Impact Award for Pandemic Innovation in 2022.
Beyond immediate delivery, the service established a resilient, standards-aligned foundation for national digital services operating under high pressure and public scrutiny.
How we can help you do the same
If your organisation needs to deliver national or large-scale digital services under regulatory, policy or public pressure, we can help.
Answer Digital works with public sector organisations to design and deliver secure, inclusive services that scale safely, adapt to change and maintain trust. We focus on creating delivery confidence where the stakes are high and failure is not an option.