Senior Software Engineer

Senior Software Engineer – Internal Developer Tooling Location: Krakow, Poland or Sofia, Bulgaria Function: Platform Engineering / Developer Tooling Level: Senior (4–8 years) We're hiring a Senior Software Engineer to join a Platform team building the internal tooling that empowers engineering teams across the organization. You'll design, build, and maintain high-impact developer tools — CLI applications for environment setup, CI/CD modernization frameworks, data access libraries, and self-service platform capabilities — that directly accelerate how engineers ship software. This is a hands-on role where architecture instincts matter as much as writing clean code. You'll own tools end-to-end: from spotting friction in developer workflows, through design and build, to adoption and ongoing support. What You'll Work On Tooling & Developer Experience: Build and evolve applications that streamline environment provisioning, configuration, and everyday developer workflows.CI/CD Modernization: Design next-generation CI/CD pipelines and drive adoption of modern GitOps workflows and reliable deployment practices.Data Access Libraries & SDKs: Develop internal libraries providing consistent, secure, performant access to data stores — abstracting complexity away from consuming teams.Internal Tooling & Automation: Identify repetitive pain points across engineering and build reusable tooling to eliminate them. Responsibilities Architect and deliver internal tools and libraries that are well-defined, modular, secure, scalable, and actively maintained.Contribute across the full development lifecycle — architecture, prototyping, testing, development, and support.Drive modern engineering practices through code and design reviews; champion DevOps principles and high-quality telemetry.Evaluate emerging technologies through proof-of-concept work and recommend adoption where they fit.Lead design discussions and align teams on architectural decisions for shared platform components.Mentor junior engineers through coaching, pairing, and code/design reviews. AI Proficiency Proficient integrating AI coding assistants, CLIs, and MCPs into daily development workflows.Uses AI effectively across the SDLC — planning, design, implementation, debugging, deployment, and observability.Builds reusable AI tooling (agent rules, skills, internal MCPs) that compounds team productivity, with sound judgment on when AI is (and isn't) the right tool.Balances AI-driven velocity with engineering rigor — automated testing, structural guardrails, and CI checks to validate AI-generated code. What We're Looking For Required 4–8 years of professional software engineering experience building production systems at scale.Bachelor's degree or higher in Computer Science, Engineering, or a related field.Deep proficiency in Python — OOP, design patterns, packaging, dependency management, and building maintainable libraries and CLI tools.Demonstrated ability to design well-structured, loosely coupled systems and make trade-offs between simplicity, extensibility, and performance.Hands-on experience with cloud platforms (Azure, AWS, or GCP).Experience with Docker, Kubernetes, and CI/CD pipelines (GitHub Actions, Jenkins, or similar); exposure to GitOps (Flux, ArgoCD) is a plus.Experience with relational databases (PostgreSQL, MSSQL) and NoSQL/key-value stores, with the ability to design clean data access abstractions.Strongly Preferred Experience building internal developer tools, platform SDKs, or CLI frameworks.Experience with data platform technologies (Spark, PySpark, Databricks, Airflow, or Dagster).Exposure to modern data architectures (Delta Lake, Iceberg, data catalogs).Hands-on experience with observability tooling (Datadog, Grafana/Prometheus, OpenTelemetry, Statsig).Track record of driving developer adoption of platform tools and improving engineering productivity. Tech Environment Cloud: Azure (primary), AWS | Orchestration: Kubernetes | Data Platforms: Spark, Databricks, PySpark | IaC: Terraform | Observability: Datadog, Grafana/Prometheus | CI/CD: GitHub Actions | Languages: Python (primary) NB: We value strong fundamentals and adaptability over specific tool expertise