Senior iOS Engineer (Product Team) - Freelance

Proton

About Proton  Join Proton and build a better internet where privacy is the default Proton was founded in 2014 by scientists from CERN on a simple truth: privacy is a fundamental human right. Since then, we’ve built the world’s largest encrypted email service (Proton Mail) and expanded into Proton VPN, Proton Drive, Proton Pass, and Proton Calendar—tools used by millions globally to protect their freedom, fight censorship, and keep their data safe. In some situations, Proton has literally helped save lives! We are profitable, independent (no VC control), and selectively hire from the top ~1% of applicants. Our 500+ team members across 50+ countries come from leading organizations and elite academic backgrounds. We move fast, keep hierarchy light, and prioritize impact over optics. If you want to do meaningful work with exceptionally high-caliber people, this is it. Join us and do work you can truly be proud of. Check our open-source projects here! The Role Based in our Barcelona office, you’ll join one of several high-impact product teams across Proton Pass, Proton Wallet/Payments, and Proton VPN, helping build privacy-first products used by millions around the world. From secure password management and identity protection to encrypted financial tools and internet freedom products that help users bypass censorship and surveillance, you’ll work on technically ambitious products with real-world impact. As a senior engineer, you’ll collaborate closely with product, design, and engineers across Proton to build and ship high-quality experiences on Apple platforms, helping define what “great” looks like for privacy-focused consumer products at scale. What we are looking for * You have extensive experience building and shipping high-quality iOS applications * You care deeply about product quality, usability, and delivering exceptional user experiences * You have strong experience building maintainable, scalable, and testable mobile architectures * You are comfortable working across large codebases and collaborating across multiple teams * You have experience mentoring engineers and raising the technical bar within a team * You have a strong understanding of performance, concurrency, and mobile memory management * You are comfortable navigating ambiguity and contributing to product and technical discussions * Experience with privacy, security, encryption, sync systems, or offline-first architectures is a strong plus * Rust experience is a plus, but not required as we continue moving towards a platform-independent Rust logical core communicating with the iOS application via generic interfaces What We Offer * Work that Matters: millions of people trust Proton with their privacy. We answer only to our users — not advertisers, not investors with conflicting agendas, not governments. The work you do here is real, and the impact is measurable. (read more about our impact here) * Stock Options: at Proton, we all have the opportunity to be owners of the company. From day one, you have a real stake in what we're building. When Proton wins, you win. * Technology: you'll get the right hardware and the right software you need to do your best work. * Learning & Development: we invest in your growth because sharp people make us better. Proton is one of the fastest ways to accelerate your career because you'll be thrown into real challenges, with real ownership, from day one. * Employee Benefits: your wellbeing isn't an afterthought. We offer strong health coverage, solid retirement options, generous leave, and wellness support so you can bring your best self to work every day * In-Person Collaboration: Amazing things happen when passionate, smart, and purposeful people get together in the same room. With offices across Geneva, Zürich, Barcelona, London and more, you'll spend most of your time collaborating face-to-face with people who genuinely care about what they're building * Food: Lunch and snacks are on us every day in our offices so you can focus on the work and not on what's for lunch. * Transport: getting to the office shouldn't cost you. We cover public transport, bike allowances, or parking, whichever works for you. * Flexible Working: you own your schedule. Set hours that work for you and your team — because outcomes matter more than when the clock says you started.

Wallapop

Wallapop is a Barcelona based scale-up driven by the purpose to empower people to embrace a more conscious and human way of consumption. We believe in a world where collaborative economy is mainstream. This is what drives us. 💫 Wallapop operates in Spain, Italy and Portugal, offering a catalogue of several hundreds of millions of products and services. Powered by technical innovation and continuous improvement, we bring together the scale & trust of classifieds with the marketplace’s convenience & reach. 🌱 Our mission is to enable a connected trade ecosystem, making 2nd-hand the norm through smart use of technology.   THE CHALLENGE 🧩 Are you ready to kickstart your engineering career? We are launching our first cohort of our Full-Stack Graduate Program—an immersive, 21-month rotational journey designed to cultivate adaptable, high-impact T-shaped software engineers.   At Wallapop, we believe in building solid vertical depth in a core technology while fostering a horizontal, working fluency across the rest of our ecosystem. Over the course of 21 months, you will complete three distinct 6-month rotations through our core engineering chapters—shipping real production code used by millions—alongside a 3-month business immersion rotation: * Backend Chapter (6 months): Deep dive into robust, scalable server-side systems using Kotlin & Java (with Spring Boot, Ktor, AWS, and microservices). * Frontend (Web) Chapter (6 months): Build responsive, elegant, and modern web applications using React & Angular. * Mobile Chapter (6 months): Craft exceptional native mobile experiences on either iOS (Swift) or Android (Kotlin/Java) depending on team fit. * Business Immersion (3 months): Step outside of engineering to complete a rotation in non-engineering departments. This will allow you to get to know other parts of the business and gain an understanding of how Wallapop operates as a whole.   You will be supported by a comprehensive, three-tier mentorship model including a dedicated Anchor Engineering Manager for your entire 21-month journey, a rotating Chapter Mentor for daily pair-programming, and a Rotation Team Manager to integrate you into cross-functional agile rituals. We also treat AI-native developer tooling (GitHub Copilot, Claude, etc.) as first-class citizens to help you ramp up and contribute fast! WHAT YOU WILL DO 👇 Build and ship features on systems used by millions of buyers and sellers — real work, not training exercises. * Rotate across engineering chapters over 18 months, gaining hands-on experience in Backend (Kotlin/Java), Frontend/Web (React/Angular), and one mobile platform (iOS or Android). * Rotation in a non-engineering department over 3 months. This will allow you to get to know other parts of the business and gain an understanding of how Wallapop operates as a whole. * Work with senior and mid-level engineers and cross-functional stakeholders who will mentor you, review your code, and push you to grow. * Use AI tooling as a first-class part of your workflow — Copilot, Claude, and similar tools are how we work, not an afterthought. * Participate fully in team life: standups, planning, retros, code reviews. * Own your learning — flag blockers fast, ask questions freely, and teach back what you're learning. WHAT WE’RE LOOKING FOR 🔎 We care more about how you think and learn than about what's on your CV. We're looking for people who are genuinely curious, who want to understand systems rather than just pass tests, and who are motivated by building things that matter. * Fresh graduate — University (e.g., UPC), Grado Superior, or equivalent. This is your first professional engineering role. * Basic coding fluency — you've built things, you can debug, you understand what your code actually does. * Curiosity — you ask why, not just how. * Learning velocity — you pick things up fast and lean into unfamiliar territory. * Openness to breadth — you're not here to be a one-stack specialist. You want to understand the whole picture. * Care — you want to do software well, for the right reasons. * Fluent English — Ability to communicate clearly and effectively with English-only stakeholders across Wallapop. WHAT WE OFFER 🚀 * Permanent contract from day one — you're an engineer at Wallapop, not a trainee on a clock. * 21 months of structured rotation with real ownership at every stage. * A dedicated mentor per chapter + a stable Anchor Engineering Manager across the full program. * AI-native onboarding — you'll be set up with the tooling and context to contribute fast. * A clear path to becoming a fully fledged Full-Stack Engineer at the end of the 21-month rotation. * Competitive graduate salary. * Wallapop's standard benefits package (detailed below!). Do note that all our jobs are 📍 Barcelona based. We follow a hybrid model where flexibility rules. We commit to a minimum of 6 days per month in the office. Each team self-organizes to decide on cadence and in-person/remote rituals. Wallapop is an equal opportunity employer. We celebrate diversity and are committed to creating an inclusive environment for all employees as we want Wallapop to be a place for everyone. Additionally to the opportunity to contribute to an agile product set up and work together towards achieving our meaningful mission, we offer the following 🍭 Perks & Benefits: * Generous individual learning budget of 2k per year * Free office meals, lunch selection from different providers * Group and individual English, Catalan & Spanish lessons as part of our working day * Private Health Insurance with Alan * Flexible working hours + Intensive Fridays * Flexible remuneration to deduct from gross salary (kindergarten/food/transport check) * Gym & Wellness plan, including physiotherapist in the office * Generous referral Program & Charity Donation * Bonus for weddings & newborns * Wallapop Renta (Tax income support) * Monthly plan for free shipping, bumps & home-pick-up on our services * Work anniversary Gifts and Birthday Surprises * Contribution towards your WIFI in your monthly payroll * One-off payment based on compensation package to go towards setting up your home office * Relocation package (monetary support and legal advice) and visa sponsorship, if applicable * 26 holidays per year * TOP hardware of your choice (latest Apple or Windows)   What does the hiring process for this position look like? 👀 Intro Call - run by talent acquisition, focus on providing more information about the role and the company as well as going over your experience, motivation, and expectations. This usually takes 45-60 minutes. Conversation with an Engineer: In this step, you will meet with a member of our engineering team. We will dive deeper into your technical background and problem-solving approach to assess if you are a strong fit for the team. It is also a great opportunity for you to ask specific questions about our tech stack and the day-to-day work. In-Person Assessment Centre (Mid-September): If selected, you will be invited to our office for a collaborative assessment centre. You will participate in exercises alongside other candidates, giving you a chance to showcase your skills, meet our team, and get a real feel for how we work.

Okta

Secure Every Identity, from AI to Human Identity is the key to unlocking the potential of AI. Okta secures AI by building the trusted, neutral infrastructure that enables organizations to safely embrace this new era. This work requires a relentless drive to solve complex challenges with real-world stakes. We are looking for builders and owners who operate with speed and urgency and execute with excellence. This is an opportunity to do career-defining work. We're all in on this mission. If you are too, let's talk. Auth0 provides an unparalleled authentication experience for hundreds of millions of users worldwide. Our commitment to reliability is a key foundation of our product and our dedication to exceeding customer availability expectations is a core engineering focus. As a Senior Site Reliability Engineer, you'll join our SRE team based in Europe to ensure our production systems are not only operational but also resilient, scalable, and ready for exponential growth. This isn't just about keeping the lights on; it's about directly contributing to the platform's core resiliency and robustness. You'll be a hands-on builder, crafting solutions that make our system more reliable by design. What you’ll do: * Design and build custom software in Go to enhance the platform's reliability, resiliency, and redundancy. * Partner with engineering teams to embed reliability principles, improving the availability, performance, and observability of our services. * Use your deep understanding of infrastructure and observability principles to identify opportunities for improvement within the product and implement solutions. * Contribute to our follow-the-sun on-call rotation, providing rapid, effective response to critical incidents and using your expertise to troubleshoot, mitigate or accurately escalate production issues. Because our team is globally distributed, your on-call shifts will only occur during your standard local working hours. * Develop and refine our SRE tooling and processes, focusing on automation and operational efficiency. * Define, document, and champion reliability best practices across the organisation. What you'll need to be successful: This role requires a unique blend of a software engineer's mindset and operational expertise. You'll thrive in this role if you have: * A proactive and systematic approach to problem-solving, with a high degree of ownership. * Proven experience in a production environment supporting large-scale, mission-critical applications with a high degree of autonomy. * Proficiency in at least one programming language, with a preference for Go. You should be comfortable writing custom applications, not just scripts. * Experience with infrastructure as code (Terraform), container orchestration (Kubernetes, Docker) and GitOps (ArgoCD). * Demonstrable expertise in a major cloud provider (Azure, AWS, or GCP). * A strong grasp of microservices architecture, databases (SQL, NoSQL), and networking fundamentals, so you can understand how custom code can solve platform-level issues. * An understanding of core SRE principles, including SLIs, SLOs, and error budgets. * Experience in an on-call rotation for a 24/7 cloud-based environment. * Exceptional communication and collaboration skills, with a proven ability to work effectively in a remote, distributed team, where tasks may be self-driven. We're looking for someone who is not just looking for a job, but a career-defining opportunity to tackle complex challenges at a massive scale. If you're a curious and motivated engineer who's passionate about building reliability directly into the platform, we'd love to hear from you. #LI-Remote P17684_3303790 Below is the annual salary range for candidates located in Spain. Your actual salary will depend on factors such as your skills, qualifications, and experience. In addition, Okta offers equity (where applicable), bonus, and comprehensive healthcare coverage and financial benefits including paid time off and parental leave in accordance with our applicable plans and policies. To learn more about our Total Rewards program, please visit: https://rewards.okta.com/esp. The annual base salary range for this position for candidates located in Spain is between: €58.000—€80.000 EUR The Okta Experience * Supporting Your Well-Being  * Driving Social Impact  * Developing Talent and Fostering Connection + Community We are intentional about connection. Our global community, spanning over 20 offices worldwide, is united by a drive to innovate. Your journey begins with an immersive, in-person onboarding experience designed to accelerate your impact and connect you to our mission and team from day one. Okta is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, ancestry, marital status, age, physical or mental disability, or status as a protected veteran. We also consider for employment qualified applicants with arrest and convictions records, consistent with applicable laws. If reasonable accommodation is needed to complete any part of the job application, interview process, or onboarding please use this Form to request an accommodation. Notice for New York City Applicants & Employees: Okta may use Automated Employment Decision Tools (AEDT), as defined by New York City Local Law 144, that use artificial intelligence, machine learning, or other automated processes to assist in our recruitment and hiring process. In accordance with NYC Local Law 144, if you are an applicant or employee residing in New York City, please click here to view our full NYC AEDT Notice.