{"id":2115928,"url":"https://alion.io/job/itds-poland-senior-fullstack-engineer-react-and-kotlin-specialists","title":"Senior Fullstack Engineer – React and Kotlin Specialists","company":{"id":879,"name":"ITDS Poland","domain":"itds.pl","url":"https://alion.io/company/itds","size_band":"201-500","is_staffing_agency":false,"employer_type":"staffing","is_intermediary":false,"listed_via":null,"ats_vendor":null,"truth_index":null},"role":"Mobile","role_family":"Mobile","seniority":"senior","employment_type":"contractor","work_mode":"hybrid","remote_scope":null,"remote_scope_basis":null,"remote_working_hours":null,"hiring_geo_confidence":"structured","locations":["Warsaw, Poland"],"countries":["PL"],"hiring_countries":[],"hiring_countries_total":0,"salary":{"min":18480,"max":21840,"currency":"PLN","period":"month","gross":null,"usd_annual":67044},"salary_estimate":null,"experience_years_min":3,"visa_sponsorship":false,"relocation_package":false,"has_equity":false,"technologies":[{"name":"Agile","optional":false},{"name":"AI Agents","optional":false},{"name":"Copilot","optional":false},{"name":"GCP","optional":false},{"name":"Jest","optional":false},{"name":"Kotlin","optional":false},{"name":"Machine Learning","optional":false},{"name":"Playwright","optional":false},{"name":"Recommender Systems","optional":false},{"name":"Spring Boot","optional":false},{"name":"SQL","optional":false},{"name":"TypeScript","optional":false},{"name":"Vitest","optional":false},{"name":"Java","optional":true}],"status":"live","first_seen_at":"2026-10-08T11:05:10Z","employer_posted_date":null,"last_verified_at":"2026-10-08T11:05:10Z","board_verified":false,"closed_at":null,"days_open":11,"trust":{"level":"not_scored","repost_count":null,"flags":[],"days_open":11},"description":"Unleash innovation — design the future of intelligent advertising ecosystems!\nWarszawa-based opportunity with hybrid work model.\nAs a Senior Fullstack Engineer – React and Kotlin Specialists, you will be working for our client, a leader in building advanced advertising tools, focusing on creating intelligent recommendation systems and automating campaign management for advertisers on Allegro Ads. Join a mission-driven project that revolutionizes how businesses grow through cutting-edge technology and data-driven insights, offering exciting avenues for professional growth and innovation.\nYour main responsibilities:\nDevelop and maintain backend services using Kotlin, integrating machine learning-driven recommendation engines in collaboration with data science teams.\nBuild scalable, event-driven architectures to process large data volumes within cloud environments, leveraging GCP.\nDesign and implement high-performance APIs to support analytical dashboards and market benchmarks.\nCreate and optimize scalable microfrontends using React, prioritizing accessibility and server-side rendering for analytical tools.\nCollaborate with cross-functional teams to deliver seamless, secure, and efficient software solutions.\nEnsure high code quality through testing frameworks such as Jest, Vitest, or Playwright, with a focus on performance and reliability.\nContribute to evolving microservice architectures, utilizing Spring Boot, MongoDB, SQL, and cloud-native tools.\nParticipate actively in code reviews, sprint planning, and technical discussions to foster continuous improvement.\nYou're ideal for this role if you have:\nAt least 3 years of experience in full-stack development, with a focus on React and Kotlin.\nStrong proficiency in TypeScript, React, HTML/CSS, and backend technologies like Kotlin, Spring Boot, and microservices.\nExperience working with cloud ecosystems, preferably GCP.\nSolid understanding of database management, including MongoDB and SQL.\nFamiliarity with event-driven architectures and large-scale data processing.\nAbility to communicate effectively in Polish and English.\nExperience working in an Agile environment with a focus on delivering high-quality software.\nIt is a strong plus if you have: (optional)\nCertifications related to GCP or microservices architecture.\nExperience with agentic coding tools like Copilot/OpenCode.\nKnowledge of accessibility standards (a11y) and performance optimization techniques.\nLanguage Required for the role:\nPolish (Communicative)\nEnglish (Communicative)\nEligibility for this role:\nOnly candidates with an existing legal right to work in the European Union will be considered for this role.\n#MAKEYourCareerBETTER\nInterested? Apply now and include your CV (preferably in English) along with a statement confirming your consent to the processing and storage of your personal data.\nTech stack\nReact\nKotlin\nTypeScript\nMicroservices\nREST APIs\nSpring Boot\nMongoDB\nSQL\nGCP\nEvent-Driven Architecture","description_format":"text","description_chars":2961,"description_truncated":false,"requirements":{"experience_years_min":3,"management_years_min":null,"team_size_min":null,"manages_managers":false,"education":null,"security_clearance":false,"languages":[]},"benefits":["Hybrid work"],"hiring_locations":[],"hiring_excludes":[],"relocation_offered":false,"industries":["IT Consulting & Digital Transformation","IT Staffing & Staff Augmentation"],"lifecycle":[{"event":"open","at":"2026-10-08T22:59:03Z"}],"visa":[],"liveness":{"score":61,"band":"ok","label":"Likely open","p_open":1,"p_active":0.81,"p_room":0.75,"age_days":10,"expected_fill_days":12,"reasons":["seen:10","velocity","win:late"],"computed_at":"2026-10-19T05:45:15Z"},"pay":{"stated_usd_annual":67044,"is_top_pay":false},"html_url":"https://alion.io/job/itds-poland-senior-fullstack-engineer-react-and-kotlin-specialists","json_url":"https://alion.io/job/itds-poland-senior-fullstack-engineer-react-and-kotlin-specialists.json","meta":{"generated_at":"2026-10-19T23:02:12Z","cache_seconds":300,"methodology":"https://alion.io/methodology","terms":"https://alion.io/terms","contact":"https://alion.io/contact","api":"https://alion.io/developers","about":"Alion is a live layer of people, companies and AI agents: who they are, whether they are real and active right now, what they do and how to work with them, readable by people and by agents and paid per call.","catalog":"https://alion.io/catalog.json","usage":{"tier":"crawler_verified","counted_by":"address","units_charged":1,"used_today":1957,"day_limit":null,"remaining_today":null,"minute_limit":300,"resets_at":"2026-10-20T00:00:00Z"}},"offers":[{"id":"company.slices","title":"One company in depth, by slice","status":"live","price":{"credits":0.02,"usd":0.002,"plus_per_slice":{"credits":0.05,"usd":0.005}},"unit":"per company, plus each slice with data","note":"the employer in depth","call":{"mcp_tool":"get_company","arguments":{"id":879},"rest":"https://alion.io/mcp/rest/get_company?id=879"},"human":"https://alion.io/catalog?offer=company.slices&for=job%2Fitds-poland-senior-fullstack-engineer-react-and-kotlin-specialists"},{"id":"market.stats","title":"A market slice: pay, demand and time to fill","status":"live","price":{"credits":1,"usd":0.1},"unit":"per slice","note":"pay, demand and time to fill for this role and place","call":{"mcp_tool":"market_stats"},"human":"https://alion.io/catalog?offer=market.stats&for=job%2Fitds-poland-senior-fullstack-engineer-react-and-kotlin-specialists"},{"id":"job.search","title":"Open jobs by role, technology, place, pay and visa","status":"live","price":{"credits":0.02,"usd":0.002},"unit":"per posting in a list","note":"similar open postings","call":{"mcp_tool":"search_jobs"},"human":"https://alion.io/catalog?offer=job.search&for=job%2Fitds-poland-senior-fullstack-engineer-react-and-kotlin-specialists"},{"id":"company.verify","title":"Is this company real and active right now","status":"pilot","price":null,"unit":"per company","request":{"url":"https://alion.io/catalog/request","method":"POST","body":"{\"offer\": \"company.verify\", \"for\": \"job/itds-poland-senior-fullstack-engineer-react-and-kotlin-specialists\", \"note\": \"what you need it for\"}"},"human":"https://alion.io/catalog?offer=company.verify&for=job%2Fitds-poland-senior-fullstack-engineer-react-and-kotlin-specialists"}]}