{"id":4068218,"url":"https://alion.io/job/asos-principal-software-engineer","title":"Principal Software Engineer","company":{"id":39790,"name":"ASOS","domain":"asos.com","url":"https://alion.io/company/asos","size_band":"201-500","is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"SmartRecruiters","truth_index":null},"role":"Backend","role_family":"Backend","seniority":"lead","employment_type":"full_time","work_mode":"hybrid","remote_scope":null,"remote_scope_basis":null,"remote_working_hours":null,"hiring_geo_confidence":"structured","locations":["London, United Kingdom"],"countries":["GB"],"hiring_countries":[],"hiring_countries_total":0,"salary":null,"salary_estimate":null,"experience_years_min":null,"visa_sponsorship":false,"relocation_package":false,"has_equity":false,"technologies":[{"name":"Agile","optional":false},{"name":"AI Agents","optional":false},{"name":"Azure","optional":false},{"name":"C#","optional":false},{"name":"CI/CD","optional":false},{"name":"Go","optional":false},{"name":"Rest API","optional":false}],"status":"live","first_seen_at":"2026-11-11T11:50:00Z","employer_posted_date":"2026-11-11","last_verified_at":"2026-11-11T12:28:07Z","board_verified":true,"closed_at":null,"days_open":0,"trust":{"level":"ok","repost_count":null,"flags":[],"days_open":0},"description":"We're ASOS. We blend our flair for fashion with our love of cutting- edge technology, but more importantly were interested in how we can bring the best out of you.\nWe exist to give people the confidence to be whoever they want to be, and that goes for our people too. At ASOS, you're free to be your true self without judgment, and channel your creativity into a platform used by millions.\nThrough our Fashion with Integrity strategy we are driving diversity, equity and inclusion across every aspect of ASOS and ensuring every ASOSer can be their authentic self at work. We want our people to be whoever they want to be, because we believe people who bring their best selves to work, do their best work.\nAs a Principal Software Engineer, your goal is to make engineering, and our engineers, better every day. You are approachable and collaborative, and you actively nurture a diverse and inclusive workplace.\nYou work closely with engineering teams to sharpen their practices, processes and technology, and to explore new ones. You help them clear technical hurdles of any size, and when it helps, you roll up your sleeves and build alongside them.\nYour work spans the full stack: our customer-facing apps and web, and the .NET microservices, APIs and data behind them. You will help teams build consistent, reliable experiences end to end, and you will keep growing your own range as you go.\nYou will help lead ASOS into the age of agentic commerce. AI agents are changing how people discover, compare and buy fashion, and you will be at the centre of how we respond. You will turn bold ideas into working proofs of concept, work alongside leading names in the industry, and bring the best of it to life in the products millions of customers use every day.\nKey Responsibilities\nAccelerating our agentic commerce journey\nProve it fast. Lead rapid proofs of concept that test how AI agents can discover, recommend and buy fashion through ASOS. Go from idea to working prototype in weeks, learn from real results and move on quickly from what does not work.\nWork with the best. Build relationships with industry leaders, including technology partners, AI platform providers and industry groups. Bring their thinking into ASOS and make sure ASOS has a voice in how agentic commerce develops.\nBuild the foundations. Shape the technical groundwork agents will rely on: agent-ready APIs, rich product and catalogue data, identity, payments, and guardrails for trust, security and privacy. Keep ASOS aligned with emerging agent standards and protocols.\nMake change happen. Take what works from prototype to production with the teams who will own it, so promising ideas become secure, reliable and observable customer experiences.\nBring people with you. Share demos, findings and practical guidance across the engineering community, and help colleagues build confidence with agentic technology.\nStay responsible. Champion responsible AI. Customer trust, data protection and transparency come first in everything we try.\nTechnical leadership\nBe a technical authority across front-end and back-end systems: guide teams, solve problems, review and underwrite designs, and act as the point of escalation for the toughest engineering challenges.\nWork across codebases and platforms to level up each one, using shared best practice and consistent architecture where it makes sense.\nOwn and evolve the architecture of our front-end and microservice landscape. Set direction, make and record sound architectural decisions, and weigh trade-offs clearly. Shape how front ends and back ends fit together, including API design, contracts, integration patterns and the boundaries between teams and services.\nDesign for scale. Make sure our systems stay fast, available and cost-effective through peak trading periods and as the business grows.\nChampion performance, reliability, security and accessibility in everyday delivery, from the customer's device through to our services and infrastructure.\nEngineering practices and productivity\nWork with product development teams to make it as easy as possible to commit code that follows our guidelines.\nPartner with peers to find and introduce tools, technologies and ways of working that raise the quality and productivity of ASOS Engineering.\nEvaluate and introduce AI-assisted development tools, with clear guidance on security, code review and quality.\nDefine and champion good engineering practice across the community, refining existing approaches and suggesting new ones.\nQuality and delivery\nMake sure software going into production meets ASOS standards: well tested, observable, secure and of high quality. Use monitoring and telemetry to guide decisions.\nBuild and sustain highly productive teams focused on delivery, through strong collaboration and ownership.\nPeople and skills\nGrow engineers across the stack through mentoring, pairing and learning sessions, so more people can work confidently across front-end and back-end systems.\nAbout you\nWe appreciate that you may not tick all of the technical boxes listed below. If you feel like you have the right experience for the job, but don't hit every piece of criteria, we would still encourage you to apply!\nA highly experienced, senior engineer with a proven record of guiding multi-discipline teams through the full delivery lifecycle of complex, large-scale, distributed software systems.\nDeep, hands-on experience building back-end systems in .NET (C#), including REST APIs and microservices, with the ability to pick up new languages and tools quickly.\nComfort traversing front-end technologies across web and apps. You do not need to be a specialist in all of them, but you can read, review and contribute to front-end code and guide the teams who own it.\nStrong experience with microservices and distributed systems, including event-driven and asynchronous designs, service boundaries, resilience, and running them in production.\nHands-on experience building with AI, such as large language models or agents, or a strong appetite to learn fast and apply it in a commerce setting.\nA track record of prototyping quickly, then hardening what works for production.\nConfidence working with external partners and industry groups, and explaining complex technical ideas clearly to senior stakeholders.\nEnterprise-level experience building and running systems at scale: high-traffic, high-availability platforms serving millions of users, with a strong grasp of scalability, performance, resilience and cost at that size.\nExcellent architecture skills. You have designed and evolved complex systems, can explain and defend your decisions to engineers and senior stakeholders, and manage technical debt and dependencies over time.\nSolid understanding of sync and async design patterns for enterprise integration and data, which are crucial for reliable, resilient, high-performance systems.\nExperience with Agile and XP practices, and with helping teams get the most from their preferred approach.\nDeep understanding of the software development lifecycle, including quality assurance, build and deployment (CI/CD and progressive releases), and monitoring and telemetry.\nFamiliarity with the best tools and practices for each phase of delivery, such as unit testing, TDD, BDD, integration testing and performance testing.\nAwareness of application security fundamentals, including authentication, secure data handling and API protection.\nExperience designing and running cloud-native systems, ideally on Microsoft Azure.\n BeneFITS’\nEmployee discount (hello ASOS discount!) \nEmployee sample sales \n25 days paid annual leave + an extra celebration day for a special moment \nDiscretionary bonus scheme \nPrivate medical care scheme \nFlexible benefits allowance - which you can choose to take as extra cash, or use towards other benefits \nOpportunity for personalised learning and in-the-moment experiences that enable you to thrive and excel in your role","description_format":"text","description_chars":7936,"description_truncated":false,"requirements":{"experience_years_min":null,"management_years_min":null,"team_size_min":null,"manages_managers":false,"education":null,"security_clearance":false,"languages":[{"language":"English","level":"All levels","optional":false}]},"benefits":["Annual leave","Equity"],"hiring_locations":[{"name":"United Kingdom","iso":"GB","kind":"country"}],"hiring_excludes":[],"relocation_offered":false,"industries":["Commerce","E-commerce Platforms","Cosmetics & Makeup","Apparel & Fashion Brands"],"lifecycle":[{"event":"open","at":"2026-11-11T12:28:07Z"}],"visa":[{"country":"GB","licensed_sponsor":true,"adverts_offering_sponsorship_24m":0,"sanctioned_now":false,"evidence":"Licensed UK visa sponsor (Skilled Worker, Senior or Specialist Worker)","filings_12m":null,"filings_prev_12m":null,"green_card_filings_12m":null,"median_offered_wage_usd":null,"route":"Skilled Worker; 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Docs: https://alion.io/developers"}}