Software Engineer (ClimateTech SaaS)

Software Engineer Climate Tech / SaaS · London (Zone 1) / Hybrid · £40,000–£45,000 + Equity Most engineers spend their careers building things that won't matter in ten years. This isn't one of those roles. At Cauli, we're tackling one of the UK's most stubborn environmental problems: the 10.7 billion items of packaging waste generated every year — less than 9% of which is actually recycled. We're not tweaking the system. We're replacing it. Using IoT and AI-driven technology, we've already prevented over half a million pieces of single-use waste. Now we're scaling — and we need a software engineer who wants to help build the infrastructure that makes reuse as easy as throwaway. Why Join Cauli? We're a small, ambitious team led by founders who are deeply in the weeds with you. You'll work directly with our Head of Technology, with real ownership over meaningful parts of our product — not tickets in a backlog. We also know that asking you to take a mission-driven role means we need to reward you for the growth we're building together. That's why equity is a genuine part of your package here — not a footnote. Our equity options are meaningful. As an early team member, you'll receive options that reflect the ground-floor stage we're at. We're growing fast — and when Cauli wins, you win with us. A Note on Our Environment Let’s be transparent: this is a fast-paced, high-demand start-up environment, and it isn't for everyone. We work in a small, tight-knit team where expectations are high, priorities shift fast, and there are no large corporate safety nets or dedicated account support teams to delegate to. We need a true "do-er"—someone who excels in face-to-face client interactions, loves being out in the field, and thrives under pressure. The Role You’ll be a driving force across Cauli’s engineering, shipping new features and improvements across our mobile apps, backend, web, and hardware-connected software. Day to day, this means: Developing and maintaining the software behind our suite of technologyBuilding and evolving our mobile apps (iOS and Android), including our unified Kotlin Multiplatform (KMP) codebaseBuilding and maintaining backend services in PHP/Laravel that power our core productBuilding and maintaining our web app and Apple/Google Wallet integrations as part of our container tracking solutionSupporting our smart bin hardware software (Linux SBCs running Python)This is a broad, hands-on role — ideal if you like variety and want to see your work in the real world quickly. Who We're Looking For We're looking for someone with at least 1–2 years of professional software engineering experience. We care far more about what you've shipped and how you work than years on a CV. You might be a generalist who’s comfortable moving across mobile, backend, and web, or someone with deep strength in one area who’s excited to stretch into others. Either way, you’re someone who takes pride in clean, production-quality code — and wants the work to mean something. You'll need: Strong software engineering fundamentals and production-level experience in at least one modern language (e.g. Kotlin, PHP, Python)Comfort moving across different parts of the stack — mobile, backend, and web — rather than staying in one laneREST API design and integration experienceA genuine interest in picking up new languages, frameworks, or platforms as our needs evolveThese would make you stand out: Native Android or iOS development experience (Kotlin, Swift, or Kotlin Multiplatform)PHP/Laravel familiarityExposure to Apple Wallet / Google Wallet integrations or QR-based flowsPython familiarity, for crossover with our smart bin codebaseCI/CD experience (e.g. GitHub Actions)Experience with payment SDKs or StripeA background in hospitality, food service, sustainability, or IoT — not required, but a genuine plus What We Offer Equity Options: Competitive options as part of the salary package.Time Off: 30 days annual leave (including bank holidays) + your birthday off + Christmas shutdown (around 35 days total).Culture: A small, diverse, supportive team — regular socials, a founders-led environment, and work that matters.Perks: Company pension (NEST), Techscheme, and Cyclescheme. A Few Practicalities You must currently have the right to work in the UK. We're unable to offer visa sponsorship for this role.This role is hybrid, with time in our London Zone 1 office. How to Apply We don't use algorithms to screen people out. We want to hear your voice. To apply, send the following to jo.liang@caulibox.com with the subject line: Software Engineer Application Your CVA cover letter — tell us why you're the right person to help us end the era of single-use waste.We can't wait to hear from you!