**Model:** Remote / Hybrid / On-site (to be defined) **Employment Type:** CLT or PJ (to be defined) **Team:** Daily collaboration with an international team, **primarily Japan (JST)** **Languages:** **Intermediate English required** \| **Japanese (basic to intermediate) is a strong differentiator** What We’re Looking For We are building a team to develop and evolve a highly critical product (modern architecture, extensive integrations, real security requirements). We seek a **genuinely senior engineer**: autonomy, technical rigor, product vision, and an excellent delivery standard. Responsibilities * Design and implement **full-stack solutions**, focusing on **security, performance, observability, and resilience**. * Build and maintain production-grade **mobile applications** (releases, stability, telemetry, performance). * Build and evolve **backends and integrations** (APIs, events, message queues, real-time systems). * Define and reinforce **Secure SDLC practices**: threat modeling, rigorous code reviews, security and quality automation. * Collaborate with the international team (JST), clearly documenting and discussing engineering decisions. Requirements (Mandatory) **Experience and Maturity** * **5–7+ years** of software development experience with significant production deliveries. * Experience with critical systems and complex integrations (fintech/banking is a differentiator but not mandatory if security expertise is exceptionally strong). **Mobile / Frontend** * Advanced proficiency in **React Native + TypeScript**. * Solid experience with **Expo** (including build/release; EAS preferred). * Mastery of mobile app architecture: modularization, state management, performance, offline support, deep links, push notifications. **Backend** * Strong production experience with **Python** (FastAPI/Django/Flask or equivalent). * Best practices for APIs: versioning, idempotency, authentication, rate limiting, caching, migrations. **Security (must be practical, not theoretical)** * OWASP (Web/API/Mobile), hardening, API protection, secret management. * Well-implemented authentication/authorization (OAuth2/OIDC/JWT, RBAC/ABAC). * Applied cryptography (TLS, hashing/signing, secure storage, key management — at least solid foundational knowledge and practical application). **Languages** * **Intermediate English required** (technical meetings, alignment sessions, documentation). * **Basic/intermediate Japanese** as a differentiator (frequent interaction with Japanese team members). **UX/UI (intermediate level required)** * Strong UI sensibility: consistency, visual hierarchy, accessibility, and ability to collaborate with designers (Figma/Design System). Strong Differentiators (high impact for this product) *(This is where the “elite profile” comes in.)* **Architecture and Scalability** * **Event-driven** systems (Kafka / RabbitMQ / NATS), **WebSockets**, and real-time systems. * **gRPC**, **GraphQL**, contracts (OpenAPI), and resilience patterns (circuit breaker, retries, backoff). * Databases and caching: **PostgreSQL**, **Redis**, modeling/indexing/concurrency. **Observability and Reliability** * **OpenTelemetry**, Prometheus/Grafana, Sentry/Datadog, distributed tracing, SLO/SLI. * Experience handling incidents, conducting postmortems, and driving continuous improvement. **Infra/DevOps** * Docker, **Kubernetes**, CI/CD (GitHub Actions/GitLab CI), **Terraform**, environment management (dev/stage/prod). * Secrets and keys: **Vault**, KMS (AWS/GCP), rotation practices and policies. **Advanced Mobile** * Performance profiling, crash analytics, JSI/Hermes, native modules (Kotlin/Swift when needed). * Advanced mobile security: secure storage, device attestation (Play Integrity/DeviceCheck), abuse prevention. **Web3/Blockchain (if applicable to your roadmap)** * Wallet integrations (WalletConnect/deep links), signatures, providers, indexers. * Familiarity with account abstraction/MPC/multisig is a differentiator. **Flutter** * Flutter as an alternative/auxiliary stack (differentiator, not mandatory). How We Evaluate (Selection Process) * **Stage 1 — Video Call (Technical Interview)** * Objective discussion about real-world experience, architecture, security, technical decisions, and collaboration with international teams. * **Stage 2 — Practical Challenge (individual or team-based)** You will receive an **existing code/project** (which we’ll share) to **enhance, refactor, and elevate standards**: quality, security, architecture, testing, and/or performance (scope depends on your profile). * **Next Steps** Will be communicated **only upon passing prior stages**. To Apply Submit your LinkedIn/CV and, if available, GitHub/portfolio. If possible, highlight: * Production apps built with React Native/Expo * Practical examples of AppSec/applied security * Systems with complex and/or real-time integrations * Participation in architectural and quality decisions Job Type: Full-time Pay: Up to R$32,000.00 per month Work Location: Remote