Svelte UI Developer (f/m/x)

We develop our product offering to help wealth management to serve their clients' portfolios. For this, we build scalable solutions that need to perform with a rich history of financial data. We specialize in being breadth of offerings to support smaller firms' needs to serve their users well with a highly configurable solution with many functions.

Our platform has been built over years of experience in the portfolio management domain. We enhance business functionalities as well as strengthen our technology to scale operationally with low cost of ownership and high quality. For this work, we are looking for further Software Engineers to become full members of our team and take the tasks at hand from the Scrum backlog.

Your tasks

• Design and develop front-end components and windows for IPT/IOM trading workflows using modern Svelte / SvelteKit, with a focus on real-time responsiveness, interoperability and minimal latency

• Write testable, maintainable code with appropriate unit and component-level tests, and contribute to the team’s continuous integration pipelines

• Apply modern tooling and champion clean-code and performance standards across the front-end codebase

• Contribute to code reviews and help raise the team’s engineering standards around component architecture, accessibility, and maintainability

• Integrate UI components with IPT/IOM back-end services and other upstream/downstream trading systems via REST, WebSocket, and messaging APIs

• Iterate rapidly — prototype, refine, and ship new features on tight timelines, working directly with traders and squad stakeholders to validate behaviour

• Operate on Linux: shell navigation, log inspection, process control, and remote workflows

• Provide front-line support for UI issues in production trading installations, diagnosing problems quickly and delivering fixes with minimal disruption to live trading

• Act as a close partner to back-end engineers, product owners — translating operational feedback into concrete UI/UX improvements

• Champion UX quality by applying strong usability, layout, and interaction judgment to data-dense, high-frequency-use interfaces

Requirements

• Solid hands-on, more than 5 years of experience building production applications with Svelte (and/or SvelteKit), including component architecture, stores, reactivity, and lifecycle management

• Strong command of modern HTML, CSS, and JavaScript/TypeScript, along with browser APIs, async patterns

• Demonstrable sensitivity to usability, layout, and interaction design — particularly for data-dense, high-frequency-use professional interfaces

• Comfortable with basic Linux operations — shell navigation, package management, log inspection, process control, and remote development workflows

• Fluent English, both written and spoken

• Polish at a communicative level

What we offer 

• Great Place to Work since 2015 - it’s thanks to feedback from our workers that we get this special title and constantly implement new ideas 

• Employment stability - revenue of PLN 2.1BN, no debts, since 2006 on the market 

• We share the profit with Workers - over PLN 76M has already been allocated for this aim since 2022 

• Attractive benefits package - private healthcare, benefits cafeteria platform, car discounts and more 

• Comfortable workplace – class A offices or remote work 

• Dozens of fascinating projects for prestigious brands from all over the world 

• PLN 1 000 000 per year for your ideas - with this amount, we support the passions and voluntary actions of our workers 

• Investment in your growth – meetups, webinars, training platform and technology blog – you choose 

• Fantastic atmosphere created by all Sii Power People 

If you want to work on systems with high operational significance — apply now!