Senior / Lead Fullstack Engineer

About The RoleAplazo is building the financial layer for Latin America's commerce — and we're doing it with a tech team that's small enough to move fast but large enough to tackle genuinely hard problems.We're looking for a Senior or Lead Full Stack Engineer who is equally at home designing a backend service and shipping a polished mobile application. You'll own features end-to-end, work across a modern stack, and be part of a team that ships to millions of users across Mexico.At E2 (Senior), you independently own features and deliver high-quality, production-ready code across the stack. You're the kind of engineer who finishes what they start, writes code others can learn from, and raises quality standards around you.At E3 (Lead), you're the technical anchor of your squad. You own systems, drive architecture decisions, and make the engineers around you meaningfully better. You've been through enough production incidents, rewrites, and tech debt battles to know that the best solution isn't always the most elegant one — it's the one that gets shipped, maintained, and evolved.What You'll BuildEnd-to-end product features — from database schema to API design to the mobile experience users interact withInternal tools, merchant-facing platforms, and customer-facing mobile flowsObservability from day one — SLOs, alerts, dashboards — so you know when something's broken before users doSystems designed to be handed off: documented, tested, and legible to the engineer who touches it six months laterWhat You'll DoDesign and implement features across mobile and backend, owning the full surface areaContribute to (E2) or lead (E3) architecture and design decisions — write proposals, present trade-offs, make callsConduct rigorous code reviews — catching correctness issues, security gaps, and opportunities to mentorRespond to and resolve production incidents, and leave runbooks better than you found themUse AI tools daily — not as a crutch, but as a force multiplier for speed, testing, and explorationHelp engineers around you grow, especially through pairing, thoughtful feedback, and honest code review (E3)What We're Looking ForTechnical3+ years of fullstack experience (5+ for E3), ideally in B2C productsStrong backend skills: Java/Spring as the primary stack; Python or Go a plusStrong mobile skills: Flutter/Dart — comfortable building real production apps, not just gluing widgets togetherSolid experience with APIs (REST, GraphQL), databases (PostgreSQL, MongoDB), and cloud infrastructure (AWS: ECS, Lambda)Familiarity with microservices and event-driven architecturesGood testing instincts — unit, integration, and enough end-to-end to actually trust your buildsComfortable with CI/CD pipelines, observability tools (DataDog), and deployment in cloud environmentsAwareness of how payments platforms work — the flows, the constraints, the failure modes that matter in a BNPL or fintech productAI FluencyWe use AI tools as serious development infrastructure, not productivity theater. We expect you to:Use AI tools (Claude, Copilot, ChatGPT) daily — for coding, debugging, refactoring, and writing testsBuild and share reusable prompts or workflows that raise the team's baseline (E2)Apply AI strategically for architecture exploration, large-scale refactors, and prototyping (E3)Think critically about where AI helps and where it misleads — and teach others the differenceStay current on AI capabilities that are relevant to fintech and developmentCommunicationWrites clear technical documentation — the kind that actually gets readExplains trade-offs to engineers and non-engineers alike, without condescension or jargonFluent in Spanish; working English for cross-team collaboration with our India and international colleaguesMindsetProduct-minded: you understand the business outcome behind the ticket you're working onComfortable moving between mobile and backend as needed — no "that's not my domain" on a fullstack teamStrong ownership: you see problems through to resolution, including the unglamorous partsComfortable with uncertainty and changing priorities in a fast-scaling companyNice to HaveWeb development experience (Angular or React, TypeScript, HTML/CSS)Hands-on experience building or integrating payments systems (PSPs, payment rails, BNPL)On-call experience and genuine comfort with production ownershipContributions to shared libraries, tooling, or internal platformsExperience transitioning teams or codebases across tech stacksOur StackBackend: Java/Spring Python Go Mobile: Flutter (Dart) Web: Angular React TypeScript HTML/CSS (nice to have) Data: PostgreSQL MongoDB BigQuery GraphQL Infrastructure: AWS (ECS, Lambda) GCP (PubSub) Pulumi Jenkins CodeMagic Observability: DataDog AI tools: Claude OpenAI GitHub CopilotWhy AplazoWe're a Series B fintech on a mission to make financial access fair and simple for millions of people in Latin America. We connect buyers and merchants through a BNPL product that actually works — and we're building the technical infrastructure to support the next decade of that growth.What You'll Find HereA small, senior engineering team that moves fast and argues about the right thingsReal ownership: you'll ship features that reach millions of users, not work on internal tooling for yearsA culture that takes AI seriously — we run a company-wide hackathon with agentic AI as the theme, and we expect engineers at all levels to be fluentA team that invests in learning — through engineering workshops, architecture reviews, and direct exposure to hard production problemsAn honest engineering culture: we write RFCs, do real code reviews, and have the hard conversations before shippingOur tech vision: be the most beloved and innovative tech organization in Latin America. We're serious about it.Pro TipHow do we review your CV? Help us find you!We filter applications with the help of AI. To ensure your profile is properly evaluated, we recommend describing your experience using the keywords from this job posting.#Ly-remotePersonal data collected during the recruitment process will be processed in accordance with the Privacy Notice of Aplaz, S.A. de C.V. (“Aplazo”), available at our Privacy and Policy Notice.Aplazo does not discriminate on the basis of race, religion, skin color, sex, gender, age, ethnic or national origin, marital status, disability, social or economic status, sexual preferences, or any other condition or characteristic. Selection is based solely on the qualifications and merits of the candidates.