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Senior Software Engineer - Core Jobs

3381 Job Offers

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Senior JVM Software Engineer
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Seeking a Senior JVM Software Engineer in Warsaw for a hybrid role. Drive feature development (70% BE/30% FE) using Java, Spring Boot, React, and PostgreSQL. Enjoy flexible hours, a cafeteria system, and a supportive culture with technical mentoring. Join a telecom project requiring 4+ years of f...
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Poland , Warsaw
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Inetum
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Senior iOS Software Engineer
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Join our Warsaw team as a Senior iOS Software Engineer, also leveraging Android expertise. Develop innovative mobile solutions using Swift, Kotlin, and modern architectures like MVVM and SwiftUI. Enjoy a hybrid model, flexible hours, and a rich benefits package including mentoring and a cafeteria...
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Poland , Warsaw
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Inetum
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Senior Python Software Engineer
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Join Inetum Polska as a Senior Python Software Engineer in Warsaw. Develop AI-driven microservices with Python, FastAPI, and PostgreSQL on Azure. Enjoy a hybrid model (3 days office/week), flexible hours, and strong mentorship in an innovative team.
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Poland , Warsaw
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Inetum
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Senior Software Engineer
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Join UpGuard's mission to protect the world's data as a Senior Software Engineer. Design and build highly scalable SaaS features in a green-fields environment, using React, Go, and Kubernetes. Enjoy a hybrid/remote role from major Australian cities, with a collaborative team that values impact an...
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Australia , Sydney; Melbourne; Hobart; Brisbane
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UpGuard
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Freelance Senior Software Engineer
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Seeking a freelance Senior Software Engineer for a remote contract role based in Colombia. You will lead full-cycle development using React.js, Node.js, and AWS. The position requires 6+ years of experience, expertise in modern JavaScript stacks, and fluency in English and Spanish. Join a collabo...
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Colombia
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Seamless.AI
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Freelance Senior Software Engineer
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Seeking a Freelance Senior Software Engineer for a contract role in Costa Rica. Lead full-cycle development using React.js, Node.js, and AWS. Requires 6+ years' experience, fluency in English/Spanish, and expert full-stack JavaScript skills. Deliver high-quality solutions independently in a colla...
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Costa Rica
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Seamless.AI
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Freelance Senior Software Engineer
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Seeking a remote Freelance Senior Software Engineer for contract work. This role requires 6+ years of experience and expertise in React.js, Node.js, and Express.js. Fluency in both English and Spanish is essential. Lead full-cycle development and collaborate on innovative software projects from M...
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Mexico
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Seamless.AI
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Freelance Senior Software Engineer
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Join our team as a Freelance Senior Software Engineer in Uruguay. This contract role requires a bilingual expert (English/Spanish) with 6+ years' experience in full-stack JavaScript (React.js, Node.js). You will lead technical design, development, and deployment on AWS, ensuring high-quality deli...
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Uruguay
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Seamless.AI
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Senior Software Engineer
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Lead the development of high-quality software as a Senior Software Engineer. This remote US role requires 6+ years of experience and expertise in React.js, Node.js, and AWS. You will provide technical leadership, mentor a team, and drive projects using Agile methodologies.
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United States
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Seamless.AI
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Senior Java Software Engineer
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Join our Warsaw team as a Senior Java Engineer. Lead the migration of JBoss systems to a modern Spring Boot cloud environment using Java 17+, Camunda, and Kubernetes. Enjoy a hybrid model, flexible hours, and a rich benefits package including mentoring and a team-building budget. Apply your exper...
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Poland , Warsaw
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Inetum
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Senior Software Engineer
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Join a Cambridge-based quantum computing leader as a Senior Software Engineer. Develop cutting-edge cloud infrastructure using Python, AWS/Azure, and Terraform. Enjoy flexible work, equity, and collaborate with world-class innovators on revolutionary quantum AI and cybersecurity platforms.
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United Kingdom , Cambridge
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Gitmax
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Senior Frontend Software Engineer
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Join KAYAK as a Senior Frontend Engineer in Cambridge, USA. Build the Flights product used by millions, owning UI end-to-end with React/TypeScript. Enjoy great benefits like flexible hours, 4 weeks vacation, and a focus on work-life balance.
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United States , Cambridge
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KAYAK
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Senior Front-End Software Engineer
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Join KAYAK as a Senior Frontend Engineer in Kaunas. You will build innovative checkout flows and B2B platforms using React, TypeScript, and modern tooling. This hybrid role offers global collaboration, career growth funds, and extensive benefits.
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Lithuania , Kaunas
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3333.00 - 6600.00 EUR / Month
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KAYAK
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Senior Network Software Engineer
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Join Aruba, an HPE company, as a Senior Network Software Engineer in San Jose. Develop next-gen packet forwarding solutions, including stateful firewall, SDN, and scalable cloud applications. We seek an expert in C programming, networking protocols, and embedded/cloud systems with 6-10 years' exp...
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United States , San Jose
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133500.00 - 307000.00 USD / Year
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Hewlett Packard Enterprise
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Senior Software Engineer
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Join Fever's Engineering team as a Senior Software Engineer. Develop high-traffic Python applications, work with RESTful APIs, and mentor peers. Enjoy a home office anywhere in Spain, health insurance, and great discounts. Strong English and a focus on code quality are key.
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Spain
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50000.00 - 65000.00 EUR / Year
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Fever
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Senior Software Engineer
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Join Atlassian as a Senior Software Engineer in a distributed-first environment. You will build scalable backend microservices using modern OOP languages and cloud platforms like AWS. This role requires 6+ years of experience and offers ultimate flexibility to work from anywhere.
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Atlassian
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Senior Principal Software Engineer
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Lead large-scale, business-critical projects as a Senior Principal Software Engineer in Bengaluru. You will define long-term architecture for ITSM, leveraging 15+ years of cloud-native SaaS expertise. This role requires deep experience with AWS, distributed systems, and aligning technical solutio...
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India , Bengaluru
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Atlassian
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Senior Software Development Engineer - Routing/SASE
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Join Hewlett Packard Enterprise in San Jose as a Senior Software Development Engineer. You will design and maintain routing protocols like BGP and OSPF for our SASE platform, using your expert C programming skills. This role offers a chance to lead innovative projects within a culture that values...
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United States , San Jose
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117500.00 - 270000.00 USD / Year
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Hewlett Packard Enterprise
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Senior Security Software and System Engineer
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Join HPE's Cybersecurity Lab as a Senior Security Software and System Engineer in Aguadilla. You will design and implement security solutions, conduct penetration testing, and develop automation tools to enhance product and supply chain security. This role requires extensive experience in softwar...
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United States , Aguadilla
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Hewlett Packard Enterprise
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Senior Software Engineer - Transactional Data Platform
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Join Atlassian as a Senior Software Engineer for the Transactional Data Platform in Sydney. Design and build high-performance, scalable backend storage solutions on AWS. Leverage your expertise in Kotlin, distributed systems, and AWS services like S3 and DynamoDB. Enjoy a flexible hybrid/remote w...
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Australia , Sydney
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Atlassian
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About the Senior Software Engineer - Core role

Explore Senior Software Engineer – Core jobs and discover a pivotal career at the heart of technology innovation. A Senior Software Engineer in a Core capacity is a seasoned professional responsible for designing, building, and maintaining the fundamental, business-critical systems and services that power modern applications. This role is central to an organization's technical infrastructure, focusing on creating robust, scalable, and high-performance platforms that serve as the backbone for other products and features. Professionals in these jobs move beyond feature development to solve deep architectural challenges, ensuring the entire ecosystem is reliable, efficient, and secure.

Typical responsibilities for a Senior Core Software Engineer involve architecting and implementing scalable, cloud-native systems and distributed computing solutions. They write clean, maintainable, and thoroughly tested code with a strong emphasis on performance, reliability, and fault tolerance. A key part of the role is designing and optimizing data storage and retrieval mechanisms, often working with relational and non-relational databases. These engineers actively collaborate with cross-functional teams, including product management, DevOps, Site Reliability Engineering (SRE), and quality assurance, to define technical roadmaps and operational excellence. They are also tasked with mentoring junior engineers, conducting code reviews, and establishing best practices for the entire engineering organization.

The typical skill set and requirements for these high-impact jobs are comprehensive. Candidates generally possess 5+ years of progressive software development experience, with deep proficiency in one or more backend-oriented languages such as Go, Java, C#, or Python. A strong foundation in computer science fundamentals—data structures, algorithms, and system design—is essential. Practical expertise with modern cloud platforms (AWS, Azure, GCP), containerization (Docker), and orchestration (Kubernetes) is standard, as is experience with microservices architecture and API design. A security-first mindset and understanding of DevOps principles, including CI/CD pipelines and infrastructure as code, are highly valued. Beyond technical acumen, successful Senior Core Engineers demonstrate exceptional problem-solving abilities, a passion for elegant and scalable design, and the leadership skills to drive complex projects from conception to deployment. If you are seeking jobs where you build the foundational technology that enables everything else, a Senior Software Engineer – Core position represents the pinnacle of backend engineering challenges and opportunities.

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