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.

We 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.

We're looking for a Mid-level iOS Engineer to join our Analytics & Experimentation Product Delivery Team and own how customer behavior is captured in our iPhone and iPad apps. This role is about building reliable, well‑governed analytics and experimentation instrumentation at scale, and working collaboratively with product and engineering teams across ASOS to make the data they depend on trustworthy. Our app is used by over 8 million active users globally, maintains an excellent App Store rating, and is built using modern iOS technologies including the latest versions of Swift. You'll be contributing to a mature, well‑supported platform where quality, reliability and user experience matter — and you'll be the iOS voice in a team that spans web, Android, back-end and analytics engineering. What you'll be doing:

• Implementing and maintaining analytics event tracking in the iOS app following iOS best practices and platform guidelines
• Working closely with product managers, analysts and data engineers to translate event specs into instrumentation, and making sure iOS events conform to the agreed schemas, naming conventions and data contracts
• Collaborating within an agile, cross‑functional team, and supporting other ASOS iOS teams who contribute tracking through our inner source model — reviewing pull requests and helping them validate their events
• Investigating and resolving data quality issues, such as discrepancies between platforms or missing and incorrectly populated properties, and taking ownership through to a permanent fix
• Supporting experimentation on iOS, including Optimizely SDK integration, experiment exposure and variant events, and the operational monitoring behind them
• Supporting code quality, maintainability and testing so that tracking changes ship safely and behavioral data stays reliable

About you

• Experience building iOS applications using Swift and the core iOS frameworks
• Experience integrating third‑party SDKs into a production iOS app analytics, experimentation or similar (e.g. Mixpanel, Optimizely) or a strong appetite to pick this up
• An understanding of how mobile events are batched, queued and flushed, and the trade‑offs between data completeness, battery and network performance
• Knowledge of common software design patterns and architecture concepts, and an interest in designing instrumentation that's consistent and easy for other teams to adopt
• An interest in writing clear, maintainable code and improving existing codebases
• Awareness of privacy and consent requirements and how they apply to customer tracking on mobile
• Comfortable debugging data problems as well as code inspecting payloads, comparing against expected output, and working with analysts to confirm a fix (SQL or Databricks familiarity is a bonus, not a must)
• Familiarity with unit testing and a willingness to contribute to test coverage
• Experience with UI automation tools

What's in it for you?

• Competitive salary, pension, and private medical care scheme
• Performance related bonus
• Flex benefits allowance - which you can chose to take as extra cash, or use towards other benefits
• 25 days paid annual leave + an extra day for your birthday
• Employee discount (hello ASOS discount!)
• Tech Develops - our internal tech focussed skills development programme to focus on your personal growth as a technologist
• Opportunity to represent ASOS at industry leading events
• Opportunity to help shape and drive our DE&I initiatives in Tech (like our WIT movement and Diversity mentoring in Tech)
• Opportunity to make an impact from day one and work with the latest in cutting edge of technology