• Contribute to the architecture of high-load services and grow the existing C# / .NET Core codebase. • Build new product features and integrations, including the AI layer (voice, real-time, and — on the horizon — video and emotion recognition). • Design and operate async pipelines on RabbitMQ: delivery guarantees, idempotency, error handling, backpressure. • Work with MS SQL schema and queries under load: indexes, execution plans, hot-path optimization. • Hold the bar on code quality across the team: code review, testing, observability, engineering standards; influence technical decisions beyond your immediate area.

• Lead technical decisions for major platform capabilities and translate business needs into practical technical roadmaps. • Serve as a domain expert, defining scalable and maintainable domain boundaries and service architectures. • Design, build, and evolve backend capabilities and APIs across multiple systems and domains. • Take ownership of end-to-end product features, including scalability, reliability, and operational excellence. • Drive engineering best practices through hands-on coding, mentorship, and technical leadership. • Collaborate closely with product, engineering, and business stakeholders to deliver impactful solutions. • Communicate complex technical concepts clearly to both technical and non-technical audiences. • Promote modern software engineering practices including Domain-Driven Design (DDD), SOLID, GRASP, and API-first architecture.

• Conduct investigations, explorations, or code experiments to gain knowledge and unblock the team's technical obstacles within the project context; • Promote the use of software development best practices; • Ensure technical excellence in the execution of the products they are involved with and maintain a high level of functional and non-functional quality; • Be willing to take calculated risks to achieve objectives, as well as provide constructive criticism for the organization's growth in a calm and thoughtful manner; • Continuously pursue new knowledge and deepen technical expertise in their area of work and the technologies they use; • Contribute to the collaborative construction of the project's solution autonomously, in alignment with the team's development process; • Identify and signal potential risks in the progress of their project activities, based on the metrics used, and participate in designing alternatives to mitigate them; • Contribute collaboratively to the planning of project activities; • Define and explain their technical decisions based on good code design practices, detailing the solutions used to clarify and resolve potential doubts; • Work in an agile team, using software best practices, automated testing, and CI/CD.

Role Description As a Senior Backend Engineer on our Detection team, you will develop, support, and maintain the core hCaptcha application tools and services that detect and verify user events. You will work closely with Security and Machine Learning engineers to continuously build features that improve hCaptcha's capabilities by leveraging languages such as JavaScript and or Go to solve problems that impact users on a global scale. You will practice DevSecOps, handling operations around your code including security implementations, monitoring, automation, and production systems. Our customer-focused organization means you will interact directly with enterprise customers and startups when needed, alongside our product, customer success, and sales teams. Using AI: Coding agents are indisputably useful tools. We provide access to the top 3 models, and were early adopters of evals-first development flows. Familiarity with coding using agents is part of all interviews. However, reliability and correctness are critical for us. You will need to read and understand every line of code with your name on it, and it will be reviewed by both people and machines. What will you do: - Collaborate with team members and domain experts to execute on solutions that directly impact the ability to detect and mitigate fraud and automation. - Design and implement features that aim for low-latency, high-availability, transparent performance insights. - Write clearly structured, maintainable, well-documented, and tested code that meets open-source quality standards. - Support engineering excellence through code reviews, test automation, and on-call participation. What you will learn: - Experience working with systems that serve hundreds of millions of daily users. - Security and Machine Learning expertise through product development and company knowledge sharing. - Cutting-edge technology to be leveraged in solutions to combat the ever evolving cybersecurity landscape. Qualifications - 4+ years of hands-on experience in backend engineering roles. - Proven experience building scalable solutions with JavaScript and/or Go. - Expertise in Web APIs, HTTP, SSL, and database management. - Strong background with serverless and containerization architectures. - Proficiency in network protocols and distributed systems. Requirements - Production experience with Python and Rust or Go. - Knowledge of security frameworks (OWASP, CISA), attack vectors, botnets, etc. - Experience working across infrastructure such as developing CI/CD pipelines, metrics-driven deployments, managing system resources, etc. Benefits - Fully remote position with flexible working hours. - An inspiring team of colleagues spread all over the world. - Pleasant, modern development and deployment workflows: ship early, ship often. - High impact: lots of users, happy customers, high growth, and cutting edge R&D. - Flat organization, direct interaction with customer teams. We celebrate equality of opportunity and are committed to creating an inclusive environment for all team members. Join us as we transform cybersecurity, user privacy, and machine learning online! Please note that all positions require pre-employment screening, including third-party verification of work history, education, and identity, as well as a final in-person interview and identity verification step, which will be conducted in your country of residence.