Senior Backend Engineer Tech Lead

We are the company that stands behind the spectacular success of CKEditor , used by millions of people around the world. At CKSource we produce software components that other developers use to build their applications (WYSIWYG editor, file manager, document converters, etc.). Our flagship product is CKEditor 5 – an open-source, modern JavaScript (soon TypeScript) rich text editor with custom data model and virtual DOM – check our GitHub repository . We are part of Tiugo Technologies, a launchpad for new developer platforms, helping software companies accelerate growth, increase operating efficiency, and scale their business. Tiugo contains a suite of brands that are API-first, market-leading developer platforms focused on content creation and digital collaboration. Tiugo's current family of brands includes CKEditor, TinyMCE, ButterCMS, and Uploadcare. Together our products have powered millions of software applications and websites. Enabling content and communication in everything from Microsoft to NASA, you might not know our name, but you've probably used our software. Your role As a Senior Backend Engineer on our AI team, you will be a technical leader driving the strategic evolution of AI capabilities powering CKEditor 5. This is a unique opportunity to work at the intersection of AI and content creation—where LLMs meet their most natural application: text processing. While other companies struggle to find meaningful AI use cases, we're building AI features that fundamentally enhance how millions of users create and interact with digital content. Building on the foundation we established with our first AI release in October 2025, you'll lead the next phase of innovation—designing and scaling backend services that integrate Large Language Models from providers like OpenAI, Anthropic, and Google Gemini for contextual text predictions, automated content generation, and intelligent text processing. This is a rare chance to shape the future of rich text editing at scale, working on problems that directly impact how people write and communicate across the web. Want to see what we've built so far? Check out our AI features in action at https://ckeditor.com/ckeditor-5/demo/ai and imagine where you could take them next. Our core stack includes TypeScript, JavaScript, and Python. We're looking for an experienced engineer with curiosity about AI who can lead this evolution thoughtfully, balancing cutting-edge innovation with production-ready implementation, and helping us define best-in-class engineering standards. Key Responsibilities Leading the technical evolution of AI-powered backend services, guiding the architecture toward scalable, maintainable solutions. Leading and mentoring a growing team of engineers, instilling a culture of excellence, innovation, and collaboration. Designing and delivering strategic Proofs of Concept (POCs) that showcase the potential of AI in transforming content creation experiences. Setting the technical direction and standards for the team—driving adoption of engineering best practices. Engaging in code reviews, technical planning, and cross-functional collaboration to ensure the highest quality results. Writing clean, maintainable, and well-documented code that balances clarity with structure. To be successful in this role you need the following: Proven experience as a Staff Engineer, Tech Lead, or similar senior engineering role in a high-scale, complex application. Interest and foundational knowledge in AI technologies—you don't need to be an AI expert, but you should be eager to learn and grow in this space. Familiarity with cloud architectures and scalable backend systems. Deep expertise in JavaScript/TypeScript. Knowledge of SQL and/or NoSQL databases. Strong understanding of software architecture principles and modern engineering practices. Outstanding problem-solving skills and the ability to think critically and creatively. Proficiency in English (at least B2 level). Nice to have: Familiarity with AWS/Azure, CI/CD, and scalable cloud architectures. Experience working with LLMs and AI providers such as OpenAI, Anthropic, or Google Gemini. Hands-on experience integrating AI capabilities into production applications. Strong technical ownership and collaboration skills, with the ability to mentor others and share knowledge effectively. Excellent communication skills – capable of guiding both technical and non-technical stakeholders. Why join CKSource: Our people are a huge part of what makes CKSource a great place to work Aside from a great team, some of our benefits include: B2B contract-based monthly remuneration is 30.000 - 36.000 PLN VAT or its equivalent on the employment contract. Quarterly and annual financial bonuses depending on the company's performance. Flexible schedule and the possibility to work fully remotely. Professional development resources (up to 5 days of additional leave and 6 000 PLN yearly). LinkedIn Learning access. Extra leave for Tiugo Day - our company's foundation day and your birthday. English lessons with a native speaker and an online language platform where you can learn English, Spanish, and German. Access to a mental health and well-being platform with 24/7 dedicated psychological support. Private medical care (Enel Med or Medicover) and Multisport card. 2 weeks of paid parental leave for our contractors. Recruitment process HR interview with Anna Cicha Senior HR Generalist Technical interview with Jacek Bogdański (Engineering Manager) & Bartek Ciołek (Team Leader) Interview with Bartek Czerwonka (Senior Director of Engineering)