Software Development Engineer in Test (SDET)

London Hybrid | Series A AI Infrastructure Startup

It is hard to build a reliable system. It is even harder to prove that it is reliable.

Our client is redefining how enterprise software is tested. Their AI native platform automates test data, test case generation, and environment provisioning, enabling engineering teams to ship faster while reducing compliance and operational risk. Trusted by Tier 1 banks and global financial institutions, the company has recently completed a successful Series A round backed by leading global investors.

With rapid enterprise adoption and a hybrid architecture spanning SaaS control plane and on premises agent data plane, they are now hiring a Software Development Engineer in Test to take ownership of quality engineering at scale.

This is a deeply technical SDET position focused on building robust automated systems, not manual testing.

Reporting to the Head of Engineering, the SDET will define and own the end to end test strategy across both cloud and agent components. The platform operates across distributed, database heavy, and security sensitive environments, meaning quality must be embedded at every layer of the stack.

The successful candidate will design, implement, and maintain multi layer automation across UI, API, contract, integration, and distributed system scenarios. This includes building and maintaining UI automation frameworks using Playwright or Selenium, alongside backend automation in Kotlin or Java using JUnit, Testcontainers, REST assured, or Ktor based tests.

A key responsibility will be validating behaviour across multiple database engines including PostgreSQL, MySQL, and SQL Server. The SDET will write complex SQL queries, validate joins and window functions, analyse query plans, and test indexing strategies, transaction handling, connection management, replication topologies, and backup and restore flows. This is a hands on database intensive role requiring strong technical depth.

The role also involves building a protocol level test harness for remote agent communication. This includes simulating asynchronous communication, injecting failures, modelling network instability, and running chaos style scenarios to validate resilience under real world conditions. Ensuring agents running inside customer networks remain secure, performant, and compliant is a critical part of the mission.

Quality gates and trend reporting will be embedded into the GitHub Actions CI CD pipeline to ensure automated validation on every release. The SDET will also implement observability driven testing practices, leveraging logs, traces, and metrics to detect regressions, performance bottlenecks, and edge case failures that traditional assertions may not capture.

Collaboration is essential. The SDET will work closely with Product Managers and Solution Architects to refine acceptance criteria, surface technical risks early, and validate complex enterprise workflows. As the company grows, this role offers a clear progression path toward leading and building out a broader quality engineering function.

This opportunity will suit a strong engineer who happens to specialise in testing. Candidates should have hands on experience within cloud native or hybrid architectures and feel comfortable validating distributed systems and asynchronous protocols.

Experience with Docker and Kubernetes to spin up realistic test topologies is important, as is familiarity with CI CD tooling such as GitHub Actions. Exposure to observability stacks such as OpenTelemetry, Prometheus, and Grafana will be highly advantageous, particularly where these tools are used to derive intelligent test assertions.

Security, compliance, or data privacy testing experience is a plus given the nature of the customer base and the environments in which the platform operates.

In return, the company offers a competitive salary, meaningful equity, hybrid working between home and London offices, up to one month per year working from anywhere, generous annual leave including your birthday off, private medical cover, a dedicated learning and development budget, regular team offsites, and strong family leave policies.

Above all, this is an opportunity to engineer reliability into mission critical enterprise systems within a high growth AI infrastructure business.

If you are an SDET who wants to build sophisticated automation, validate complex distributed systems, and shape quality at the heart of a scaling product, this is a role worth exploring.