Lead Node.js Developer / Tech Lead (Anti-Fraud System) - remote friendly (EMEA)

You'll define the technical vision and lead the development of the core of our intelligent anti-fraud system, solving challenging engineering problems such as:

Real-time Scoring Engine:

• Design and scale a flexible rules engine that evaluates the risk of each transaction with a p99 latency of just a few milliseconds. This includes complex cascading checks - from digital fingerprinting to behavioral pattern analysis.
• Architect a system that analyzes data slices over various time windows to detect anomalies, conversion drops, and coordinated attacks at the merchant, gateway, or regional level.

High-Performance Analytics:

• Build and optimize a powerful analytics subsystem responsible for processing millions of transactions post-factum to power rich dashboards and visualizations.

Complex Data Models & Customer Profiling:

• Manage dozens of interconnected entities (transactions, merchants, terminals, customers) and design logic for asynchronous profile aggregation based on indirect attributes - to create a unified 360° customer view.

You will make architectural decisions that directly impact the security and financial efficiency of our clients' businesses, under high load and strict fault-tolerance requirements.

Key Responsibilities

• Architect and strategically evolve core services of the anti-fraud platform.
• Make key technical decisions and conduct Design and Code Reviews.
• Mentor and technically develop the engineering team, establishing best development practices.
• Optimize system performance: identify bottlenecks, refactor critical code areas, and perform profiling.
• Design and develop data pipelines using Kafka, Flink, and ClickHouse to ensure end-to-end data delivery and processing.
• Design robust messaging architectures with RabbitMQ and Kafka ensuring guaranteed delivery, idempotency, and correct event ordering.
• Design scalable database schemas and write high-performance queries for PostgreSQL and ClickHouse (including use of ReplacingMergeTree and AggregatingMergeTree engines).

• 10+ years of commercial development experience, including at least 3 years as a Tech Lead or Architect.
• Proven experience designing and launching complex, high-load systems from scratch.
• Expert-level proficiency in Node.js, TypeScript, and NestJS - with deep understanding of the event loop, garbage collection, and framework internals.
• A polyglot engineer with production experience in several languages (e.g. Java, Go, Python) and ability to choose the right tool for the job.
• Deep understanding of database internals (PostgreSQL, ClickHouse); experience optimizing queries using EXPLAIN and designing schemas for heavy workloads.
• Professional-level expertise in RabbitMQ and Kafka at an architectural level: understanding of patterns (Saga, CDC, Outbox), replication, and fault tolerance.
• Experience designing advanced caching and state management scenarios with Redis.
• Experience with stream processing systems (Apache Flink, Spark Streaming) and solid understanding of Change Data Capture (CDC) concepts.
• Degree in Computer Science or a related technical field.
• Experience building anti-fraud systems is a major plus.
• Fluent in Russian (B2 or higher) - required for daily communication within the team.

AI-Related Requirements (Critical)

• You don't just use AI - you evangelize it within the team, develop best practices, and evaluate the impact of new tools.
• Strong understanding of modern LLMs and ability to select appropriate tools for code generation, data analysis, or rapid prototyping.
• Experience working in Cursor IDE or building similar AI-assisted development workflows.

• Competitive salary based on your experience and expertise.
• Fully remote work format with flexible start times.
• High level of autonomy and direct impact on the product and company's technical strategy.
• Work on a technically complex and meaningful product in the fast-paced fintech domain.
• A team of strong engineers focused on quality and results.
• A modern, carefully selected tech stack - with zero legacy.
• Budget for education, international conferences, and professional literature.
• Corporate access to cutting-edge LLM models.

SmartCore is a fintech holding building infrastructure for the next generation of payments. Our solutions cover the entire financial operations cycle - from core banking and processing to cards, wallets, and anti-fraud systems. Our product is a high-load, multi-component system that analyzes millions of transactions in real time, detects complex fraud schemes, and provides our clients with advanced risk management tools. We operate at the intersection of Big Data, real-time processing, and complex business logic, where the cost of an error is measured in millions - and a few milliseconds of delay matter. We are now looking for an experienced Technical Lead ready to take ownership of the architecture and development of core components of our anti-fraud platform and lead a team of engineers.