Staff / Senior Staff Software Engineer – AI Systems

CKSource Holding LTD.; Polska; Hybrid; PLN 357,000 - 446,000; Full time

Benefits offered by this job

Remote work

Professional development budget

LinkedIn Learning access

Extra leave for Tiugo Day

English lessons

Mental health support

Private medical care

Multisport card

Parental leave for contractors

Job summary

CKSource Holdings is seeking a hands-on Staff/Senior Staff Software Engineer to drive the architecture and technical direction of the backend AI-powered systems in CKEditor. You will own end-to-end design, API boundaries, and reliability while delivering scalable solutions that integrate LLMs and external services.

The role is hands-on with coding and mentoring, balancing simplicity with long-term maintainability, and involves collaborating across teams to advance AI capabilities in CKEditor.

Qualifications

• Proven experience designing and delivering complex production systems at Staff or Senior Staff level.
• Strong hands-on experience with TypeScript, Node.js, software architecture, and distributed systems.
• Experience building LLM- or AI-powered features in production, including testing, evaluation, observability, and reliability.

Responsibilities

• Lead the architecture and technical direction of AI-powered systems, from early exploration to production and beyond.
• Design scalable, maintainable systems, making sound decisions about APIs, service boundaries, reliability, performance, security, and cost.
• Turn complex product ideas into experiments, prototypes, and production-ready solutions.
• Build reliable LLM integrations and establish practices for testing, evaluation, monitoring, and improving AI features.
• Stay hands-on by writing and reviewing code, solving complex technical challenges, and mentoring engineers.
• Influence engineering practices and help teams adopt AI development tools without compromising code quality or maintainability.

Skills

TypeScript

Node.js

Software architecture

Distributed systems

LLM integrations

Testing and observability

Mentoring engineers

End-to-end ownership

Influence decisions

AI features

Tools

AWS

Job description

CKSource builds CKEditor, an open-source rich text editor used by millions worldwide. We\'re part of Tiugo Technologies, alongside TinyMCE, ButterCMS, and Uploadcare.

Your role:

We\'re looking for a hands-on Staff / Senior Staff Software Engineer to drive the architecture and technical direction of backend of AI-powered systems in CKEditor.

CKEditor AI is already in production, with features like AI Chat, Quick Actions, and Review. We\'re expanding our AI platform, integrating LLMs, contextual data, APIs, and external systems.

This is an individual contributor role, not an ML research or people-management position. You\'ll combine strong software engineering fundamentals with the challenges of building reliable, scalable AI-powered products.

Key Responsibilities:

• Lead the architecture and technical direction of AI-powered systems, from early exploration to production and beyond.
• Design scalable, maintainable systems, making sound decisions about APIs, service boundaries, reliability, performance, security, and cost.
• Turn complex product ideas into experiments, prototypes, and production-ready solutions.
• Build reliable LLM integrations and establish practices for testing, evaluation, monitoring, and improving AI features.
• Stay hands-on by writing and reviewing code, solving complex technical challenges, and mentoring engineers.
• Influence engineering practices and help teams adopt AI development tools without compromising code quality or maintainability.

To be successful in this role you need the following:

• Proven experience designing and delivering complex production systems at Staff, Senior Staff, Tech Lead, or equivalent level.
• Strong hands-on experience with TypeScript, Node.js, software architecture, and distributed systems.
• Experience building LLM- or AI-powered features in production, including testing, evaluation, observability, and reliability.
• Strong architectural judgment and the ability to balance simplicity, scalability, and long-term maintainability.
• End-to-end ownership, from ambiguous technical challenges to successful production delivery.
• Ability to influence technical decisions, mentor engineers, and collaborate effectively across teams without formal authority.

Nice to have:

• Multi-provider LLM integrations, AI evaluation frameworks, tracing, or experimentation.
• AWS, infrastructure as code, and event-driven architectures.
• Experience building developer platforms, APIs, SDKs, or open-source products.
• Experience creating shared libraries, frameworks, or internal platforms.

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 32.000 - 40.000 PLN + VAT (or its equivalent on the employment contract) - the final level and compensation will depend on your experience, technical expertise, and the scope of your previous responsibilities.
• 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, PZU or Medicover) and Multisport card.
• 2 weeks of paid parental leave for our contractors.