Senior Software Engineer

ob descriptionResale is growing rapidly, with the global second-hand clothing market expected to grow from around $288bn today to nearly $400bn by 2030. Yet the work of listing, managing, and selling individual items is still manual, expensive, and inefficient. Listing Monster is building the professional resale platform for people who buy and sell goods at scale — from full-time resellers to charities and ambitious side businesses.We’re a small, experienced team building practical software that solves real commercial problems using AI. We care about thoughtful engineering, clean solutions, and real progress — not hype.We’re growing and looking for a Senior Product Engineer to help us scale both our platform and the way we deliver functionality to customers.This is a hands-on engineering role for someone who has built and shipped production software at meaningful scale before, and knows what good looks like.Who This Role Is ForThis role is ideal for someone who has already spent several years building real products used by real customers.You are someone who has:A strong academic background in Computer Science, maths or a related disciplineHas worked on and scaled production systems with meaningful usageHas helped teams ship faster and understands that done doesn’t end with the releasing of codeThinks deeply about product impact, not just technical implementationEnjoys improving systems, processes, and engineering cultureCan take ownership of ambiguous problems and move them forwardHas experience in architecting distributed systemsStrong understanding of databasesWe’re looking for someone who can help us create an amazing product by making better technical decisions, improve delivery, and raise the level of engineering across the company.What You’ll Actually Be DoingYou’ll be:Helping us architect the overall platformBuilding and shipping important product featuresHelping scale our platform as usage growsImproving how quickly and reliably we get functionality to customersWorking across the product, backend, frontend, AI, and operations parts of the systemIdentifying bottlenecks in our product and engineering processesImproving reliability, observability, performance, and maintainabilitySupporting and mentoring more junior developersHelping turn customer and business needs into well-designed technical solutionsThis is not a role where you’ll just be handed tickets.We’ll expect you to understand the product, challenge assumptions, spot risks early, and help us build the right things in the right way.What We’re Looking ForEssentialStrong experience building and maintaining Software as a ServiceExcellent programming fundamentalsComfortable working with UX and Product ManagementComfortable working across a modern web application stackGood judgement around architecture, trade-offs, and technical debtExperience shipping customer-facing product featuresClear communication and strong ownershipAbility to work independently in a small teamA pragmatic approach to engineering — thoughtful, but not over-engineeredStrong signalsYou’ve helped scale a product, platform, or engineering team beforeYou’ve worked in a startup or scale-up environmentYou’ve a strong understanding of observability and shipping codeYou’ve made meaningful contributions to architecture or technical directionYou’ve mentored junior engineersYou care about product outcomes, not just code qualityWhat Success Looks LikeIn this role, success means helping us move faster without becoming fragile.You’ll help us:Refine our product offeringShip useful functionality to customers more frequentlyKeep the platform reliable as usage growsMake better technical decisions earlierReduce unnecessary complexityImprove engineering standards and habitsBuild systems that are easier to change over timeWe want someone who has seen what good looks like at scale and can help us bring the right lessons into our stage of growth.Salary & LocationSalary: £100k-£130k depending on experienceLocation: Onsite in our London office at least 3 days per week, SE1 9PGBenefits: Private healthcare, 25 days holiday, pensionWhat It’s Like to Work HereSmall team, low egoDirect communicationPragmatic engineering decisionsReal customers using what we buildWe’re a startup, which means things evolve — but we’re not chaotic. We plan carefully and build deliberately.You’ll have a meaningful say in how the platform develops, how the engineering team works, and how we turn ideas into reliable customer-facing functionality.There’s a lot to build, and we’re looking for someone who can help us do it well.