Senior Kotlin / Java Software Engineer - Application Framework

KAYAK, part of Booking Holdings (NASDAQ: BKNG), runs a large-scale travel search platform used by travelers worldwide to find flights, hotels, rental cars, and vacation packages. The company also offers KAYAK for Business, which provides travel management solutions to organizations. Its network includes well-known brands like momondo, Cheapflights, and HotelsCombined. KAYAK aims to make exploring the world easier by building the best travel search engine and values innovation and real impact from its employees. Role overview As a Senior Java Software Engineer based in the Berlin office, you will play a key role in developing and refining the features behind KAYAK’s search and booking systems. The team collaborates with over 200 travel partners, giving users access to more than 500,000 hotels and 550 airlines. Your work will help ensure smooth, reliable experiences for millions of users each day. This position requires onsite presence in Berlin at least three days per week. What you will do Enhance search and booking algorithms to meet the needs of major corporate clients worldwide. Develop and maintain high-performance integrations with third-party APIs, including those for airlines, hotels, and rental car providers. Take ownership of your designs from concept through deployment, with a focus on code quality and system performance. Join code reviews and architectural discussions to keep the K4B project modular and reusable as KAYAK continues to grow. Requirements Bachelor’s degree in Computer Science or a related field. At least 4 years of professional experience working with Java. Strong knowledge of the Spring ecosystem (Spring/Spring Boot) and hands-on experience with both relational (SQL) and NoSQL databases such as PostgreSQL, MySQL, or Redis. Clear and effective communication skills in English. Ability to independently design and deliver engineering projects.

About Us Join our dynamic international team at Doctolib, based in Berlin, where we are devoted to enhancing the performance, features, and design of our essential healthcare product, the Scheduling System. Over the past decade, Doctolib has experienced remarkable growth by prioritizing pragmatic solutions and avoiding unnecessary optimizations. To sustain our momentum, we are focusing on performance as a key priority and are continuously evolving the architecture of our core features to accommodate future demands. We are currently re-engineering our Appointments Management Service from the ground up, utilizing modern event-driven, distributed technologies in line with our updated technology strategy. This pivotal service will revolutionize the way Care Teams manage appointments, ensuring patients receive quicker access to care.

Join idealo’s Clickout-to-Revenue team in Berlin, where the focus is on building and maintaining systems that help retailers monetize qualified referrals. The team’s work has a direct impact on idealo’s growth by ensuring monetization processes remain reliable and efficient. Both full-time and part-time arrangements are possible for this Senior Software Engineer position. What you will do Design, develop, and operate business and web applications on AWS Cloud. Take responsibility for the full lifecycle: architecture, infrastructure, development, testing, security, deployment, monitoring, and maintenance. Build and maintain services that handle processing and billing, integrating with key systems such as Odoo ERP and connecting to Salesforce and SAP. Work closely with colleagues from accounting, sales, account management, and other engineering teams to deliver solutions that meet changing business needs. Identify and implement process improvements, maintain high code quality, and pursue ongoing professional growth with support from idealo. Tech stack Kotlin Java AWS Odoo ERP Salesforce and SAP interfaces Location This role is based in Berlin, Germany.

Join Atolls, the world's largest community-driven shopping platform, active in over 20 markets.We empower millions to make informed spending choices across the discovery, evaluation, and (re-)purchase phases by connecting consumers with the right brands and retailers.Our diverse team of over 1,000 individuals across 10 countries develops products that millions use daily at a global scale. Here, you'll have true ownership of your work and witness its direct impact. Are you ready to help shape the shopping experiences that people trust? Keep reading.About This Opportunity:We are on the lookout for a Senior Software Engineer (Java/SpringBoot) to enhance our Shopping team based in Berlin. In this pivotal role at Atolls, you will play a critical part in enabling our consumers to maximize their value for money by delivering an outstanding shopping rewards experience online and in-store. You'll be instrumental in crafting exceptional user experiences, empowering consumers to make informed and confident shopping decisions. Your contributions will directly influence how millions of users engage with our platforms, guiding them towards making smart, fair, and rewarding choices.Our Perks:At Atolls, we are committed to fostering your professional and personal development. Here’s what we offer:A culture that champions personal and professional growth, coupled with internal mobility opportunities.A supportive and inclusive team that values diverse perspectives and innovative ideas.32 days of paid vacation plus your birthday off for optimal work-life balance.A flexible hybrid working model to accommodate your lifestyle.Access to a dedicated learning budget and internal training.Mental health coaching to support your well-being.Regular global and local events to celebrate achievements and foster connections.Opportunity for a sabbatical after three years with the company.

About KAYAKKAYAK, a member of Booking Holdings (NASDAQ: BKNG), stands as a premier travel search engine. With billions of queries on our platforms, we assist travelers in discovering their ideal flights, accommodations, rental cars, and vacation packages. We are also revolutionizing business travel with our innovative corporate travel solution, KAYAK for Business.As part of KAYAK, you will join a travel company that oversees a diverse array of global metasearch brands, including momondo, Cheapflights, and HotelsCombined. From our startup journey to becoming an industry trailblazer, innovation drives us, and every team member has the chance to leave a lasting impact. Our commitment is to develop the most efficient travel search engine, simplifying the process for everyone to explore the world.Position OverviewWe are in search of a proficient mid-level Java backend developer dedicated to implementing new features and maintaining KAYAK’s cutting-edge search and booking technology. Collaborating with over 200 travel partners and connecting to more than 500,000 hotels and 550 airlines, you will play a pivotal role in a dynamic team that ensures seamless operations, aiding millions in finding optimal accommodations and travel routes every day!This is a Fixed Term contract until September 30, 2027.This role requires working from our Berlin office a minimum of three days per week.Key ResponsibilitiesEnhance search and booking algorithms to meet the needs of our largest global corporate clients.Develop and sustain high-performance integrations with third-party APIs (airlines, hotels, and rental car providers).Take full ownership of your designs, from concept to deployment, while upholding exceptional standards for code quality and performance.Engage in code reviews and architectural direction to ensure the K4B project remains modular and reusable as KAYAK expands its enterprise reach.QualificationsBachelor’s degree or higher in Computer Science or a related field.5+ years of experience in Java programming.Hands-on experience with the Spring ecosystem (Spring/Spring Boot) and familiarity with relational (SQL) and NoSQL databases (e.g., PostgreSQL, MySQL, Redis).Excellent English communication skills.Ability to design and implement engineering initiatives with a focus on performance and usability.

Join Our Innovative Team at 1GLOBALAt 1GLOBAL, we are redefining mobile connectivity on a global scale. As a leading technology-driven mobile communications provider, we deliver seamless connectivity solutions for both enterprises and consumers. Our advanced telecom platform, featuring our proprietary global mobile core network and in-house developed eSIM technology, empowers us to operate as a fully regulated telecommunications provider across 40 countries worldwide.We partner with some of the world’s premier banks, enterprises, and digital-first businesses, including neo-banks and global consumer goods companies. With over 70 million connections, we enable our clients to innovate and scale their operations confidently within the mobile ecosystem.As a profitable and rapidly growing business, we project revenues exceeding US$200 million in 2025, with profits surpassing US$25 million. Our strong cash flow allows us to invest continuously in our infrastructure, platform innovations, and global expansion initiatives. Our recent successes have marked a pivotal phase in our journey, with significant client acquisitions propelling us into a global mobile connectivity powerhouse.Founded in 2022 by seasoned tech entrepreneurs Hakan Koç and Pyrros Koussios, 1GLOBAL is quickly emerging as a European technology leader, committed to shaping the future of global telecommunications. As a fully regulated Mobile Virtual Network Operator (MVNO) in 12 countries and a regulated telecom operator in another 28, we are headquartered in the Netherlands with R&D hubs in Lisbon, Berlin, and São Paulo. Our dedicated team of nearly 500 experts across 15 countries is driven by a singular ambition: to enhance global mobile connectivity through innovative technology and operational excellence.About the RoleDesign and develop impactful features while contributing to the architectural framework with a focus on resilience, scalability, security, and fault tolerance.Champion high code quality and best practices to maintain robust software development.Work collaboratively in an agile team environment to ensure timely product delivery and management.

Join our innovative team at redcare-pharmacy as a Senior Java Engineer. In this pivotal role, you will leverage your expertise in Java programming to develop robust, scalable applications that enhance our digital pharmacy solutions. Collaborate with cross-functional teams to drive the design and implementation of high-quality software solutions.We are looking for a proactive and detail-oriented engineer who thrives in a dynamic environment and is passionate about problem-solving. If you are ready to make a significant impact in the healthcare technology space, we want to hear from you!

Join our Clickout-to-Revenue Team, where you'll be integral to our core business model: merchants pay for qualified redirects ("Clickouts") to their shops. Your role will ensure that this monetization operates smoothly, efficiently, and transparently, significantly contributing to idealos' growth.Your ResponsibilitiesEnd-to-End Responsibility You will develop and manage business and web applications in the AWS Cloud. Together with your team, you will oversee the entire value chain (YBYO): architecture, infrastructure, development, testing, security, deployment, monitoring, on-call duties, and maintenance. Product Focus: Monetization Processes and Services You will develop services for the representation and billing of our business models. Key components include the ERP system Odoo, internal data management tools, and interfaces to Salesforce and SAP. Innovative business models require innovative solutions; hence, you will closely collaborate with stakeholders such as our accounting, sales teams, account management, and other cross-functional engineering teams. Technical Excellence You will actively contribute ideas for process improvements, emphasize high code quality, and engage in continuous personal development – we support you with various training opportunities.

About the Role scalablegmbh is hiring a Senior Kotlin / Java Software Engineer for the Client Technology team in Berlin. This role focuses on building and improving applications that support client services. The work centers on designing, developing, and maintaining high-performance systems using Kotlin and Java. What You Will Do Design and develop applications that improve client-facing technology Collaborate with engineers and stakeholders to deliver reliable solutions Apply expertise in Kotlin and Java to solve complex technical challenges Who We’re Looking For Strong experience with Kotlin and Java Comfort working in a collaborative team setting Motivation to take on challenging projects that impact client success This position offers the chance to make a direct impact on client outcomes while working with a skilled team in Berlin.

Join our innovative team at Lightspeed Commerce Inc. as a Senior Software Developer specializing in Java. In this pivotal role, you will work on our Third Party Ecosystem, contributing to the development of cutting-edge software solutions that enhance our platform's connectivity and flexibility.As a Senior Software Developer, your expertise will guide our projects, ensuring high-quality code and efficient workflows. Collaborate with a talented team of developers and stakeholders to drive our technology forward, fostering an environment of continuous improvement and excellence.

Doctolib is hiring a Software Engineer with solid experience in Java and Kotlin. This position is based in Berlin and centers on building digital products that support both patients and healthcare professionals across Europe. Role overview This role involves working on software that aims to improve healthcare access and efficiency. The team values collaboration and a shared commitment to making a difference in the medical field. What you will do Collaborate with team members to design and implement new product features Develop and maintain applications using Java and Kotlin Help create solutions that make healthcare services easier to access and manage Location This role is based in Berlin, Germany.

Join our dynamic team to develop an innovative banking platform leveraging cutting-edge technologies and modern software development methodologies.Collaborate with a passionate group of software engineers and academics dedicated to revolutionizing the financial sector.Transform complex business challenges into effective technical solutions.Design and establish connections with major financial industry players to integrate Scalable Capital with the broader financial ecosystem.

Join our innovative team at SWARCO as a Senior Java Developer in Berlin. In this pivotal role, you will be responsible for designing, developing, and maintaining high-quality software solutions that drive our projects forward. Your expertise in Java programming will be crucial in crafting robust applications that meet the needs of our clients.

Hello! We appreciate your interest in our team! Are you ready to embrace a new career challenge, or are you simply exploring opportunities? If so, you have come to the right place! We are on the lookout for a skilled Senior Backend Developer to join our dynamic team. In this pivotal role, you will contribute to the growth and advancement of our Hospitality product group, helping us to penetrate new markets and enhance our all-encompassing commerce platform. You will specifically be part of the team dedicated to developing a sophisticated, modular framework for user and permissions management. Your work on a range of projects will significantly affect the everyday experiences of thousands of customers globally and aid in revitalizing local communities. Join us as we shape the future of hospitality technology!

idealo is looking for a Senior Backend Software Engineer (m|w|d) to join the team in Berlin. This role focuses on building and operating the backend for our mobile app, which helps millions of users compare prices and shop smarter. The team takes full ownership of technical implementation, operations, and strategic direction for our services, with a strong commitment to delivering a seamless experience for mobile shoppers. Role overview This position centers on end-to-end responsibility for business and web services in the AWS Cloud. The team manages the full lifecycle of these services, from architecture and infrastructure to development, testing, deployment, monitoring, and on-call support. The goal is to ensure stability, scalability, and high performance, especially during periods of heavy traffic. What you will do Develop and operate backend services in AWS Cloud for the mobile app Design and implement APIs (REST/GraphQL) for Android and iOS applications Make architectural decisions for backend systems, including microservices Enhance cloud infrastructure using tools such as Terraform and Kubernetes Maintain high code quality through testing, code reviews, and monitoring Identify and address technical debt Introduce new technologies and improve development workflows (CI/CD, automation, AI tools) Collaboration and impact Work closely with mobile engineers and backend colleagues Contribute to technical discussions and challenge existing solutions Share knowledge through pair programming, code reviews, and tech talks Communicate complex technical topics to non-technical stakeholders Participate in on-call rotations and take responsibility during critical incidents

At Flix, we foster a technology-driven culture where creativity meets significant real-world applications. We offer competitive compensation, ample opportunities for professional advancement, and a collaborative environment that encourages ownership and innovation.We are on the lookout for a Software Engineer (Kotlin, Java) with robust Kotlin (or Java with a willingness to learn Kotlin) expertise to become a key member of our Capacity Management team in the Demand Division. The Capacity Management team is responsible for developing and maintaining systems that allocate, price, and manage seat availability across Flix. Our team handles high-throughput, real-time data pipelines and event-driven microservices to ensure smooth operations, even in unpredictable situations.As a Software Engineer at Flix, you will have the opportunity to influence systems that directly affect how millions of passengers book their seats and optimize Flix's capacity across our global network in real-time.Our tech stackLanguages & Frameworks: Kotlin, Spring Boot, Akka/PekkoData & Messaging: PostgreSQL, Kafka

As a Team Lead Java Engineer in our Remarketing department, you will spearhead architecture, solution design, development, quality assurance, deployment, monitoring, and maintenance within our service-oriented platform. This platform currently features over 300 RESTful microservices. You and your team will take ownership of a selection of applications and services.Leverage your hands-on experience and proactive attitude to tackle complex challenges effectively, providing innovative solutions and technical guidance grounded in your robust technical expertise.Take charge of the professional growth and development of your team, fostering an environment where everyone strives to improve daily.Recruit top-tier talent, exemplify leadership, and mentor your team members to push boundaries and achieve excellence.

Join Our Team at GetYourGuide At GetYourGuide, we are the world’s leading platform for unforgettable travel experiences. Since our inception in 2009, we have empowered travelers across the globe to discover and book over 150 million tours, activities, and attraction tickets. Our headquarters in Berlin is home to a dynamic team of over 800 travel experts and technologists, united by a passion for making travel magical. Explore our careers page to learn more about our culture and values. Our Mission: Technology is the driving force behind our growth at GetYourGuide. We continue to innovate in Design, Engineering, and Product to redefine the travel experience. You will play a crucial role in developing solutions that simplify customer interactions and enable our partners to thrive. From creating fintech infrastructure to enhance payment processes to contributing to our strategic growth, the impact of your work will resonate globally. As part of our Engineering team, you will collaborate with diverse, cross-functional teams to enhance the magic of travel for our users. Your Role: As a Senior Software Engineer with a focus on Frontend, you’ll be an integral part of a product team. Collaboration and a customer-centric approach are key as you tackle real-world user challenges and shape the product experience. This is primarily an 80/20 full-stack role, utilizing TypeScript and Node.js for backend development. A robust knowledge of both frontend and backend technologies is necessary, particularly in managing our Server-Driven UI backend-for-frontend (BFF) layer, which involves creating backend components that adapt to frontend requirements to elevate the user experience. Your role will require close cooperation with product managers, designers, and stakeholders, so strong collaboration and communication skills are essential. We seek engineers who not only excel technically but also effectively advocate for customer needs and align with business objectives. You’ll support the team in building and scaling our platform, ensuring a seamless and engaging user experience.

Join our dynamic team as a Senior Software Engineer specializing in JavaCard development. In this role, you will leverage your expertise to design, implement, and enhance innovative software solutions that drive our business forward. Collaborate with cross-functional teams to deliver high-quality software that meets the needs of our clients. If you are passionate about technology and eager to make an impact, we want to hear from you!