Senior / Lead Fullstack Engineer

M8l; United States; Remote; USD 49,000 - 81,000; Full time

Job summary

Aplazo is hiring a Senior or Lead Full Stack Engineer to build end-to-end features for a BNPL fintech platform serving millions across Latin America. You will own backend services and mobile apps, design APIs, and contribute to architecture decisions while maintaining high production quality.

You’ll work remotely in Mexico with a senior, fast-moving team that ships frequently and emphasizes ownership. You will leverage Java/Spring on the backend, Flutter/Dart on mobile, and modern web tech with

Qualifications

• 3+ years of fullstack experience (5+ for E3), ideally with B2C products.
• Strong backend skills: Java/Spring; Python or Go is a plus.
• Strong mobile skills: Flutter/Dart and production apps.
• APIs (REST/GraphQL), databases (PostgreSQL, MongoDB), and cloud (AWS).
• Experience with microservices, event-driven architectures, and CI/CD.
• Testing: unit, integration, and end-to-end; observability with DataDog.
• Spanish fluency; working English for cross-team collaboration.
• Familiarity with payments/fintech flows is a plus.

Responsibilities

• Design and implement features across mobile and backend end-to-end.
• Contribute to or lead architecture decisions and trade-offs.
• Conduct rigorous code reviews to improve quality and security.
• Respond to production incidents and improve runbooks.
• Leverage AI tools daily to accelerate development and testing.
• Mentor peers and help engineers grow through pairing and feedback.

Skills

Full-stack development

Backend development

Mobile development

APIs (REST, GraphQL)

Cloud (AWS)

Databases (PostgreSQL, MongoDB)

Testing (unit/integration)

CI/CD

Spanish language

Tools

DataDog

PubSub

Pulumi

Jenkins

CodeMagic

Job description

Remote in Mexico.

About the Role

Aplazo 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 Build

• End-to-end product features — from database schema to API design to the mobile experience users interact with

• Internal tools, merchant‑facing platforms, and customer‑facing mobile flows

• Observability from day one — SLOs, alerts, dashboards — so you know when something's broken before users do

• Systems designed to be handed off: documented, tested, and legible to the engineer who touches it six months later

What You'll Do

• Design and implement features across mobile and backend, owning the full surface area

• Contribute to (E2) or lead (E3) architecture and design decisions — write proposals, present trade-offs, make calls

• Conduct rigorous code reviews — catching correctness issues, security gaps, and opportunities to mentor

• Respond to and resolve production incidents, and leave runbooks better than you found them

• Use AI tools daily — not as a crutch, but as a force multiplier for speed, testing, and exploration

• Help engineers around you grow, especially through pairing, thoughtful feedback, and honest code review (E3)

What We're Looking For

Technical

• 3+ years of fullstack experience (5+ for E3), ideally in B2C products

• Strong backend skills: Java/Spring as the primary stack; Python or Go a plus

• Strong mobile skills: Flutter/Dart — comfortable building real production apps, not just gluing widgets together

• Solid experience with APIs (REST, GraphQL), databases (PostgreSQL, MongoDB), and cloud infrastructure (AWS: ECS, Lambda)

• Familiarity with microservices and event‑driven architectures

• Good testing instincts — unit, integration, and enough end-to-end to actually trust your builds

• Comfortable with CI/CD pipelines, observability tools (DataDog), and deployment in cloud environments

• Awareness of how payments platforms work — the flows, the constraints, the failure modes that matter in a BNPL or fintech product

AI Fluency

We 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 tests

• Build 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 difference

• Stay current on AI capabilities that are relevant to fintech and development

Communication

• Writes clear technical documentation — the kind that actually gets read

• Explains trade-offs to engineers and non‑engineers alike, without condescension or jargon

• Fluent in Spanish; working English for cross‑team collaboration with our India and international colleagues

Mindset

• Product‑minded: you understand the business outcome behind the ticket you're working on

• Comfortable moving between mobile and backend as needed — no "that's not my domain" on a fullstack team

• Strong ownership: you see problems through to resolution, including the unglamorous parts

• Comfortable with uncertainty and changing priorities in a fast‑scaling company

Nice to Have

• Web 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 ownership

• Contributions to shared libraries, tooling, or internal platforms

• Experience transitioning teams or codebases across tech stacks

Our Stack

Backend: 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 Copilot

Why Aplazo

We'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 here:

• A small, senior engineering team that moves fast and argues about the right things

• Real ownership: you'll ship features that reach millions of users, not work on internal tooling for years

• A 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 fluent

• A team that invests in learning — through engineering workshops, architecture reviews, and direct exposure to hard production problems

• An honest engineering culture: we write RFCs, do real code reviews, and have the hard conversations before shipping

Our tech vision: be the most beloved and innovative tech organization in Latin America. We're serious about it.

Personal 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.

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