Senior iOS Engineer (Freelance)

• Babbel is looking for a Senior iOS Engineer to help change the future of language learning within our Learning Experience teams
• This is an Individual Contributor role with team-level scope. You will work closely with product and engineering managers, designers, subject matter experts, and cross-platform engineers to build Babbel’s core learning experiences — from the learning path and exercise player to real-time speaking and conversation practice
• You own the experience end to end: it ships as a distributable Swift package consumed by Babbel’s main iOS app, and you follow it there — integration points, A/B experiments, rollout. And you’ll do this the Labs way: AI coding agents are a first-class part of how we design, build, test, and review
• Take part in all product development phases: discovery, prototyping, proposing solutions, implementing, reviewing, testing, and deploying learning experiences
• Own the engineering side of our feature workflow: shape the PRD together with product, then pick it up — write the technical spec, agree Interface Contracts with backend and partner teams, slice the backlog, and build
• Build quick prototypes to de-risk product ideas — the learnings feed the product, even when the code doesn’t
• Design and evolve the public API of our Swift package with deliberate versioning and breaking-change discipline — and land it in the main app: integration points, A/B experiments, rollout
• Collaborate closely with product managers, designers, and other cross-functional teams to define and implement features that enhance how learners progress through their learning path, exercises, and speaking practice
• Maintain and proactively improve the technology stack, build system, and the AI-agent conventions (skills, project rules, documentation) the whole team relies on
• Share what you learn: technical documentation for core features, and knowledge actively passed on to colleagues

Benefits

• 30 vacation days and flexible working hours
• BVG card or Swapfiets bike
• Jobbatical and Sabbatical options
• Many internal & external learning opportunities to choose from
• A yearly Learning & Development budget
• Visa and relocation assistance
• Full access to Babbel & Babbel Live classes
• Modern office in the heart of buzzing Berlin equipped with a family, music, faith and nap room
• Various internal communities to be part of including the Femgineers, DEI Ambassadors, Accessibility & Disability Group and more- Testing as a first-class habit: deterministic, exhaustive unit tests with controlled dependencies, snapshot tests where the UI is the contract — not coverage theater — and the CI/CD discipline to keep them green
• Experience designing or consuming evolving JSON APIs and collaborating with contract-first backend teams
• Strong, up to date Swift — including Swift 6 strict concurrency (actors, Sendable, isolation) and structured concurrency
• Comfort with ambiguity and fast iteration: directions evolve as we learn, and prototypes are a tool, not a deliverable
• An eye for good architectural decisions based on feature requirements, and knowledge of how to balance technical debt against delivery speed
• Strong opinions on state management and testable architecture — experience unidirectional-data-flow architecture, and willingness to go deep on ours
• Experience designing module boundaries, frameworks, or SDKs that other teams consume — ideally as distributable Swift packages — and the API-stability discipline that comes with it
• Deep SwiftUI experience and a solid grounding in the Apple ecosystem and Human Interface Guidelines; you think in state-driven UI and know where the framework’s sharp edges are
• An AI-first mindset — a strong must for us. You have actively embraced AI coding tools in your own work — not just autocomplete, but directing agents through real feature work and critically reviewing what they produce — and you treat prompts, skills, and project conventions as engineering artifacts maintained like code. Deep experience with our specific agent stack isn’t required — demonstrated adoption and genuine enthusiasm are
• 5+ years of experience building scalable iOS applications using Swift
• Clear, concise communication, an open mindset for feedback, and enjoyment in working closely with design and product in a lean environment
• Fluency in written and spoken English
• Experience with real-time client features — live audio capture, streaming over WebSocket/WebRTC, low-latency interactions
• Hands-on experience with agentic coding setups (e.g. Claude Code): agent skills, MCP servers, CLAUDE.md-style project conventions
• Experience working in language learning, education technology, or consumer subscription products
• Hands-on experience with The Composable Architecture and the Point-Free ecosystem (swift-dependencies, swift-sharing)
• Comfort navigating a legacy RxSwift/MVVM-C codebase — you’ll help integrate our package into Babbel’s main iOS app while it migrates to the new stack
• Experience with Tuist or other project-as-code tooling at scale (modular workspaces, binary caching)
• Experience with Swift Testing (the modern successor to XCTest)
• We are a learning company, inside and out, and we encourage you to apply even if you do not fit all the technical requirements — all candidates are assessed based on skills, qualifications, and our business needs. Please state your pronouns in your application, and let us know if you’d like to be addressed by a name other than the one appearing on your official documents