Senior Full-Stack Developer

Wallex is a FinTech company providing a secure cryptocurrency exchange platform and digital asset payment solutions.
With a vision to become a leading global FinTech enterprise, Wallex is recognized as one of the largest cryptocurrency exchange platforms in Iran, supporting the online trading of over 130 cryptocurrencies.

We are looking for a Senior Full-Stack Developer to build and operate the systems behind an AI-powered consumer application designed for young children and their parents. You will work across the mobile application, backend services and APIs, cloud infrastructure, and internal tools that power the product.

This is a broad engineering role with a strong focus on ownership. You will design and deliver complete features across the stack, from data models and backend services to user-facing interfaces, while taking responsibility for reliability, performance, security, and release. You will also contribute to technical direction, architecture decisions, engineering standards, and developer workflows.

You will work closely with Product, Design, Engineering, and AI and Creative teams to integrate generative capabilities into a fast, reliable, and trustworthy consumer experience.

Responsibilities:

• Design, build, and maintain cross-platform mobile applications for iOS and Android.
• Implement rich media experiences, including synchronized audio and visual content, playback controls, interactive moments, and graceful interruption and resume.
• Build core product flows including account management, onboarding, settings, content history, and subscription experiences.
• Develop web and internal-facing interfaces, including administrative and operational tools, when required.
• Deliver complete features across the stack, from data models and APIs to user-facing interfaces.
• Design, develop, and maintain backend services and APIs supporting accounts, profiles, entitlements, session state, and content delivery.
• Design and evolve relational and vector data stores, with attention to schema design, migrations, indexing, and query performance.
• Integrate internal AI and content generation services through well-defined and maintainable service contracts.
• Participate in system design and architecture decisions, considering scalability, security, latency, reliability, and cost.
• Identify and proactively address technical risks, bottlenecks, and architectural debt.
• Contribute to defining service boundaries, technical standards, and long-term platform direction.
• Own the path from development to staging and production, including CI/CD pipelines and infrastructure as code.
• Build and operate cloud infrastructure, including containerized services, messaging, storage, secrets management, and access controls.
• Implement reliable media delivery using appropriate approaches such as edge caching, signed access, prefetching, regional failover, and low-bandwidth fallbacks.
• Treat performance and reliability as core product requirements by defining, measuring, and improving latency and availability targets.
• Manage mobile release processes, including App Store and Google Play submissions, staged rollouts, over-the-air updates, and rollback strategies.
• Build and maintain observability across application and AI systems, including logging, tracing, alerting, latency monitoring, and cost visibility.
• Implement secure authentication, authorization, and data protection appropriate for a product used by children and families.
• Build privacy-related capabilities such as consent, data export, correction, deletion, and retention into the underlying systems.
• Ensure privacy and safety requirements are enforced consistently across downstream services and data stores.
• Collaborate with relevant teams to ensure requirements such as COPPA and GDPR-K are reflected in the product architecture and engineering practices.
• Drive engineering best practices across code quality, testing, observability, documentation, and deployment.
• Review code and provide constructive feedback to maintain a high technical standard across the team.
• Contribute to technical scoping, architecture discussions, and acceptance criteria before implementation begins.
• Improve developer workflows, internal tooling, and operational processes over time.
• Take ownership of technical decisions and communicate trade-offs clearly to technical and non-technical stakeholders.
• Work in short delivery cycles while maintaining a high standard of reliability and engineering quality.

Requirements:

• 5+ years of professional software development experience building and operating production systems.
• Strong proficiency in either mobile or backend development, with demonstrated capability across the other side of the stack.
• Professional experience with cross-platform mobile development using Flutter/Dart or equivalent native mobile technologies.
• Strong backend development experience using Python (FastAPI, Django, or similar) or TypeScript/Node.js.
• Proven experience designing and operating services on a major cloud platform, including containers, CI/CD, messaging, managed databases, and secrets management.
• Strong experience with PostgreSQL, including schema design, migrations, indexing, and query performance optimization.
• Experience with vector databases or vector search technologies is highly valuable.
• Experience with infrastructure as code, such as Terraform or equivalent tools, and multi-environment deployment workflows.
• Proven experience shipping and maintaining applications on both the App Store and Google Play, including managing the review and release process.
• Experience integrating LLM APIs or other probabilistic services, with appropriate handling of timeouts, retries, fallbacks, budgets, and observability.
• Solid understanding of software architecture, design patterns, distributed systems, and application security.
• Experience working in Agile development environments and short delivery cycles.
• Strong problem-solving and analytical skills with a strong sense of ownership.
• Excellent written and verbal communication skills.
• Fluency in English and Persian.

Nice to Have:

• Experience building consumer products for children or family-oriented products.
• Familiarity with children's privacy and safety requirements such as COPPA and GDPR-K.
• Experience with audio and image streaming, CDN architecture, or media-heavy consumer applications.
• Experience with latency optimization and designing for unreliable or low-bandwidth network conditions.
• Experience with over-the-air update tooling and staged mobile rollout strategies.
• Experience implementing subscription, billing, or entitlement systems.
• Familiarity with LLM observability, tracing, and per-request or per-unit cost tracking.
• Experience working with high-traffic consumer applications or systems with significant media workloads.
• Experience with event-driven architectures and messaging systems.
• Strong product or design sensibility and attention to interaction details.
• Experience working with TypeScript/React for web or internal tools.

We build, not watch — This is where you belong!