Senior Software Engineer

Most IoT monitoring companies buy their sensors, rent their network, and build a dashboard on top. We design the sensors, run the network, calibrate the devices in our own lab, and build the platform. If you like big data and real problems that don't stop at the API boundary, this is the job for you!About usInvisible Systems has spent over twenty years helping organisations prove compliance, cut energy use, and protect what they store. Our platform monitors legionella risk, cold chain for food and pharmaceuticals, energy usage, and environmental conditions for customers including Greggs, Greencore, Movianto, the NHS and the Irish Prison Service. Our hardware is designed and manufactured in Britain, and we're accredited to ISO 9001, 14001, 27001, 45001 and 50001.The roleWe've recently launched Hub, our next-generation data and automation platform that ingests sensor readings, metadata and diagnostics from almost any source and turns them into actions, insights, data visualisations and audit-ready compliance reports. It's TypeScript throughout: Next.js on the front end, Hono APIs, MongoDB and Redis behind it, all running on AWS Fargate and Lambda.Hub will eventually replace our established platform, which continues to serve customers in the meantime. You'll work across both - roughly 90% greenfield development building out new features in Hub and delivering on our roadmap, and 10% keeping the existing service dependable and helping shape a migration that doesn't interrupt live monitoring.You'll also get closer to the metal than most platform roles allow. The LoRaWAN network, its gateways, fleets of control devices and the secure comms links to our cellular providers are all ours.When a vaccine fridge drifts out of range or a water outlet stops being flushed, our platform is how someone finds out. Reliability and data integrity genuinely matter here, and your work will have a real-world impact.What we're looking forStrong commercial TypeScript experience with a back-end focusDemonstrable systems engineering experienceExperience working with high volume, real-time, event driven systemsExperience working with large data sets (100M+ datapoints)Solid React or Next.js experienceExperience designing and operating HTTP APIs in Node.jsPractical MongoDB - schema design, indexing, aggregation, and interpreting performance metricsA track record of owning production systems, not just shipping into themSound judgement on a young platform: knowing which decisions to make now and which to deferComfortable using AI led development workflowsWhat we offer£60k - £80k DOE + bonus + equityCompany pension contributionsHybrid working, at least two days per week in the officeBudget available for training and personal developmentThe processOur process has two stages: an introductory call first and then a more in-depth technical conversation in person.