(Senior) Fullstack Engineer (Python + React.js) - Freelance

Join Netguru, a reputable leader in digital commerce, as we partner with prominent brands to revolutionize B2B solutions, marketplaces, and retail ecosystems. Since our inception in 2008, we have empowered businesses with innovative technology, AI-driven personalization, and exceptional engineering and design expertise. Proudly certified as a B Corporation®, we are trusted by industry giants including IKEA, VW, OLX, Delivery Hero, Żabka, Wolt, Careem, and Vinted.Freelancing at Netguru:As a Netguru freelancer, you have the unique opportunity to tailor your work environment. You will determine when, where, and how you engage with projects and tasks. Our team ensures that your assignments align with your skills and interests, providing you with diverse opportunities across various industries to enhance your experience and skill set.Moreover, as a Netguru freelancer, you are not just an outsider; you become an integral part of our team with the possibility of full-time collaboration.Are you ready to make a significant impact? Come aboard Netguru, and let’s create exceptional software together.We are currently looking for a skilled Senior Golang Developer.This role is a freelance position on a B2B contract, focusing on the development and scaling of distributed systems and services. The position is 100% remote and requires the selected candidate to be available to start as soon as possible.B2B Contract | Up to 39 EUR/h | Remote | Immediate Start

About UsAt Ruby Labs, we are at the forefront of technological innovation, crafting and managing groundbreaking consumer products across various sectors, including health, education, and entertainment. Our dynamic teams are dedicated to shaping the future of consumer-oriented solutions, and we are constantly on the lookout for passionate individuals to enhance our mission. Discover more about our journey at https://rubylabs.com/about-us/.About the RoleWe are seeking an adept Middle Golang Developer to join our team. In this role, you will take charge of developing scalable, high-performance backend services and will play a key role in enhancing our billing system. As part of a cross-functional team comprising engineers and product managers, your work will focus on delivering consistent, sustainable results. We value individuals who are enthusiastic about innovation, eager to stay updated with emerging technologies, and possess exceptional communication and collaboration skills, especially in a remote setting.Key ResponsibilitiesSoftware Development: Engage in the development and maintenance of robust backend services and applications utilizing Golang.Microservices Architecture: Design, implement, and optimize microservices-based applications, ensuring they are scalable, reliable, and maintainable.Container Orchestration: Work in conjunction with the DevOps team to deploy and manage Golang applications within Kubernetes clusters, utilizing Helm for efficient package management.Database Management: Design and refine database schemas, queries, and transactions with a focus on Postgres, ensuring data integrity and performance. Use Redis to enhance application efficiency.Billing System: Develop and improve the billing system to guarantee accurate and timely processing of financial transactions.Code Review: Perform code reviews to uphold code quality, best practices, and compliance with coding standards.Collaboration: Work collaboratively with the cross-functional team, including DevOps, backend and frontend developers, QA, and product management, to grasp requirements and deliver high-quality software solutions. Maintain comprehensive documentation for code, architecture, and processes to ensure effective knowledge transfer.

Join Netguru, a leader in the digital commerce landscape, as we partner with renowned brands to elevate their B2B solutions, marketplaces, and retail ecosystems. Since our inception in 2008, we have empowered businesses with state-of-the-art technology, AI-driven personalization, and top-notch engineering and design teams. As a certified B Corporation®, we take pride in our collaborations with major brands such as IKEA, VW, OLX, Delivery Hero, Żabka, Wolt, Careem, and Vinted.How does freelancing work at Netguru?As a freelancer at Netguru, you have the flexibility to choose your working hours, location, and project tasks. We align your skills with suitable projects, providing you access to diverse opportunities across various industries. This not only enhances your experience but also allows you to broaden your skill set.Moreover, Netguru freelancers can engage in full-time collaborations, truly becoming integral members of our team. Are you ready to make a significant impact? Join us, and let’s create stunning software together.Currently, we are seeking a Senior Frontend Developer to join our team.

Join Netguru, a pioneering force in digital commerce, as we assist renowned brands in modernizing their B2B solutions, marketplaces, and retail ecosystems. Since our inception in 2008, we have empowered businesses through innovative technology, AI-driven personalization, and exceptional engineering and design teams. As a certified B Corporation®, we proudly serve major brands such as IKEA, VW, OLX, Delivery Hero, Żabka, Wolt, Careem, and Vinted.We are currently seeking a Senior Backend Engineer with robust architectural expertise to engage in a long-term project for a European client in the laboratory and biotech sector. This position is a single-developer project, requiring close collaboration with the client’s internal teams and laboratory stakeholders to clarify requirements, outline the project scope, and enhance existing backend processes. Strong communication skills are vital, as you will frequently participate in technical discussions with LIMS and laboratory teams. Your role will encompass hands-on development, legacy code refactoring, and contributing to a scalable, well-structured backend architecture. Please note that candidates must be based in the EU due to client stipulations.Position: Senior Backend Engineer (Java / Architecture)Contract: Freelance / B2B – Remote (EU Only)Rate: 36–50 EUR/hourLanguage: English C1Key ResponsibilitiesOperate independently as the sole backend engineer on the project.Refactor and modernize legacy backend systems.Enhance and expand existing microservices and backend integrations.Maintain and develop REST and SOAP interfaces.Engage with laboratory teams and LIMS stakeholders to define requirements.Guarantee stable operation of backend services in an on-premise Kubernetes environment.Work collaboratively with internal client teams to ensure architectural consistency.QualificationsTechnical Skills & ExperienceExtensive experience with Java (Spring / Spring Boot).Strong architectural and problem-solving abilities.Proficient in designing and maintaining REST APIs.Familiarity with SOAP services.Experience in microservices environments.Hands-on experience with Kubernetes (preferably on-premise setups).Background in working with or integrating LIMS systems.Solid understanding of refactoring and modernizing legacy code.Excellent communication skills for direct collaboration with laboratory stakeholders.Proficiency in English at C1 level.Must be based in the European Union.BenefitsIn return, we offer:100% remote, flexible work environment;Access to cutting-edge technology and tools;Opportunities for professional development.

About the TeamJoin the Sell Online Tribe, a dynamic group that empowers merchants to establish their presence online. We create innovative tools that enable millions of entrepreneurs, from barbers to bakers, to market their products and services effortlessly. Our core focus lies in the Online Store and Bookings products, which form the backbone of SumUp’s ecosystem, allowing merchants to manage appointments, highlight their offerings, and process payments—all from their mobile devices.We are a collaborative, cross-functional team of Product Managers, Designers, and Engineers dedicated to delivering exceptional mobile experiences. As a part of this team, you will play a crucial role in expanding into new sectors, bridging the gap between web and mobile, and making digital selling seamless for small businesses worldwide.About the RoleAs a Senior Backend Engineer, you will be instrumental in enhancing SumUp's major merchant-facing online products within the Bifrost team. You will contribute to the development and scaling of key products such as Payment Links, Virtual Terminal, and Unified Gift Cards, while also working on integration solutions that are vital for numerous other SumUp offerings.We are looking for a developer who prioritizes reliability, teamwork, and continuous growth. Your backend expertise will thrive in a high-impact environment where your contributions directly influence merchant success and team scalability.What You’ll DoEnsure scalability and continuous growth of high-priority online products at SumUpDrive the implementation, development, and integration of Online Checkouts across SumUpEngage actively in planning and review sessions at quarterly and sprint levels, providing constructive feedback and estimationsMonitor existing services, applying necessary fixes to maintain platform reliabilityDevelop new features with maintainable and testable codeEnhance application performance for scalabilityParticipate in code reviews to uphold high coding standardsYou Will Excel in This Role If:You have 5+ years of experience in backend engineering with GolangYou possess a robust understanding of fundamental system architecture, design principles, data modeling, and API designYou have substantial experience with distributed and fault-tolerant systemsYou have a passion for delivering high-quality software solutions

Spoton is looking for a Senior Software Engineer II with a focus on Golang to join the Partnerships team. This remote position based in Poland centers on building and supporting integration solutions that connect Spoton’s products with partner services. Role overview This role involves designing, developing, and maintaining scalable software that enables smooth partner integrations. Projects often have a direct impact on how Spoton collaborates with external organizations, making strong technical decisions important for success. Collaboration Working as part of a distributed team, you will engage with colleagues across different functions to improve and extend product capabilities. The Partnerships team values engineers who contribute ideas and work well with others to solve complex challenges. What you bring Deep experience with Golang in a production environment Strong skills in designing and maintaining scalable integration solutions A collaborative approach to working with cross-functional teams Interest in technology and creative problem solving

Join IDT Corporation as a dynamic and experienced Senior DevOps Engineer specializing in Golang. In this role, you will leverage your expertise in AWS, Kubernetes (both public and private cloud), Docker, Hashicorp Vault, and Consul to design, implement, and maintain robust infrastructure and CI/CD pipelines that ensure reliability, scalability, and security across all operations.

Join Nordsec as a Senior Backend Engineer and be a part of our innovative team in Warsaw. We are seeking a talented engineer experienced in Golang to help us build robust backend systems that power our applications. You will work closely with cross-functional teams to design, implement, and optimize backend services that deliver exceptional user experiences.

Netguru is a Certified B Corporation® that builds software for entrepreneurs and innovators. The team values trust, ownership, and transparency, working to create a safe and inclusive environment where everyone can be productive. Feedback is encouraged, and the company continually looks for ways to improve. Freelancers at Netguru set their own schedules and choose where and how they work. Assignments are matched to individual strengths, offering experience with projects from a range of industries. Freelancers can also explore full-time collaboration and become part of the wider team culture. Learn more about freelancing at Netguru: https://www.netguru.com/blog/who-are-netguru-freelancers Role overview This freelance position is for a Senior Ruby on Rails Developer. The role requires strong Ruby on Rails expertise, comfort with JavaScript, and familiarity with email delivery tools such as Mailgun or SparkPost. Requirements Extensive experience with Ruby on Rails Solid background in JavaScript Familiarity with email delivery tools (Mailgun, SparkPost, or similar) What Netguru offers Fully remote work (Poland-based, CET time zone +1/-1) Flexible hours and work locations Developer-friendly processes Potential for long-term collaboration Contract details Freelance, B2B contract Full-time assignment for 6 months

Join Valtech, a leading experience innovation company and trusted partner to some of the world's most recognized brands. We offer our team members numerous growth opportunities, a values-driven culture, and the chance to shape the future of customer experiences.The OpportunityAs a Senior Salesforce Marketing Cloud Developer at Valtech, you will engage in an environment focused on continuous learning, impactful contributions, and professional advancement. Your role will involve pioneering new digital solutions and reimagining customer experiences, ultimately driving transformation across various industries.

About Our Client Our client is a pioneering force in the realm of digital identity and fraud prevention, providing a state-of-the-art platform utilized by banks, fintech firms, online marketplaces, and various regulated entities globally. Their innovative solutions encompass biometric identity verification, document and image processing, and sophisticated fraud detection mechanisms, enabling customers to achieve seamless digital interactions while maintaining rigorous security and compliance with regulations. Leveraging cutting-edge technologies such as AI, machine learning, and computer vision, they facilitate identity verification, mobile deposits, and liveness detection, catering to thousands of organizations worldwide. About the Role We are in search of a Senior Full Stack Engineer who possesses a robust proficiency in backend services built with Go and modern web front-end frameworks. As a member of a dynamic cross-functional team, you will contribute to the development of cloud-native identity and fraud prevention products hosted on AWS. Your role will encompass designing and implementing APIs in Go, as well as crafting user-centric features using contemporary JavaScript frameworks, ensuring secure, high-performance experiences for both internal and external users. Key Responsibilities Design, develop, and maintain backend services and APIs in Go, leveraging AWS infrastructure with microservice or serverless architectures. Create responsive single-page and web applications utilizing React and Redux, seamlessly integrating them with backend APIs. Implement clean and reusable UI components, prioritizing user experience, performance, and accessibility. Develop and uphold automated testing protocols for both backend and frontend components, contributing to CI/CD automation processes. Collaborate closely with designers, product managers, QA, and fellow engineers to refine requirements and deliver comprehensive features. Engage in technical design and architecture discussions, aiding in the definition of interfaces between services and front-end applications. Contribute to the documentation of APIs, front-end components, and significant technical decisions. Participate in Agile ceremonies and proactively drive enhancements in team processes and engineering practices.

SKELAR is a pioneering Ukrainian venture builder dedicated to establishing international tech businesses. We collaborate with co-founders to assemble top-notch teams that excel in global markets.Currently, SKELAR operates a range of businesses across various niches, from EdTech to marketplaces. These companies consistently rank among the top startups and product firms in Ukraine, achieving high rankings in the App Store and creating platforms that millions use daily. Major media outlets like TechCrunch and Wired have featured SKELAR's businesses.We take pride in a robust team of over 1,000 specialists who possess remarkable expertise and ambitious goals. Our people are the most valuable asset of the company, and we strive to build businesses with the best talents available in the market.RiseGuide is an expert-driven microlearning mobile application designed around the principles and examples of exceptional role models. Our users are guided by insights from Andrew Huberman and Simon Sinek to break harmful habits, enhance their social media presence with strategies from Alex Hormozi and MrBeast, and develop charisma inspired by Robert Downey Jr. and Steve Jobs.Key Facts about RiseGuide:Achieved unit economics in just 6 weeks and have been actively scaling since (we had an incredible Q5 and grew fivefold last year).Over 200,000 paid users, with ratings of 4.6/5 on the App Store and 4.4/5 on TrustPilot.A team of over 60 individuals from successful tech businesses and top management programs worldwide.We aim to redefine the self-improvement industry, granting users access to expert knowledge on demand. To achieve this, we are seeking a Software Engineer (Golang) to help develop our product's backend and turn our ambitious goals into tangible achievements.What We Offer:Opportunity to make architectural decisions and build systems from the ground up.Minimal bureaucracy and maximum speed to market. A small team focused on results and rapid deployment.Fast feedback loops — your solutions will immediately impact production and influence hundreds of thousands of users.The chance to join the team early and define your area of responsibility.Pure Tech: modern stack with Zero Legacy.

Join SpotOn as a Senior Software Engineer II specializing in Golang within our dynamic order processing team. In this role, you'll leverage your expertise to design, develop, and optimize high-performance software solutions that enhance our order management systems. Collaborate with cross-functional teams to ensure seamless integration and delivery of top-notch services.

What You'll DoDesign and develop cutting-edge AI inference and model training cloud products that are optimized for Kubernetes, focusing on autoscaling inference servers and distributed training jobs across GPU fleets.Write clean, efficient, and maintainable Go code to drive Kubernetes controllers, operators, and custom resources that support AI workloads.Develop APIs, CLIs, and developer tools that streamline the deployment, lifecycle management, and monitoring of AI applications.Create features that enhance serverless container workflows for AI, ensuring rapid cold starts, resource-efficient scaling, and effective workload isolation.Contribute to the system's performance, reliability, and security, with an emphasis on AI-specific challenges such as GPU scheduling, job orchestration, and data throughput.Keep abreast of advancements in the Kubernetes ecosystem (e.g., K8s-native ML tooling, scheduling improvements, SIGs) and influence our product roadmap accordingly.

Join Netguru, a leading partner in digital commerce, as we empower top brands to innovate their B2B solutions, marketplaces, and retail ecosystems. Since our inception in 2008, we have been at the forefront of technology, utilizing AI-powered personalization and delivering exceptional engineering and design services. As a certified B Corporation®, we are proud to partner with industry giants such as IKEA, VW, OLX, Delivery Hero, Żabka, Wolt, Careem, and Vinted.What does freelancing look like at Netguru?As a Netguru freelancer, you have the flexibility to define your work style. Choose your working hours, location, and project types that align with your expertise.We ensure that you are paired with projects that match your skills, offering diverse opportunities across various industries. This approach not only enhances your experience but also allows for skill diversification.Moreover, our freelancers can engage in full-time collaborations, becoming integral members of our teams.If you are ready to make a significant impact, join Netguru, and let’s create remarkable software together.We are currently seeking AI-savvy Mid and Junior Python Developers to contribute to our client’s projects.Details:Freelance assignmentFull-time commitmentB2B contractStart date: ASAPDuration: 8-12 months (with a possibility of extension)Working hours: 9 AM - 5 PM CETSalary for Junior: up to 24 EUR/hourSalary for Mid: up to 34 EUR/hourYou will have the opportunity to work on one of three impactful projects for our client:Project #1: Develop a universal health profile for users and their families, transforming fragmented records into insightful products that promote longer, healthier lives.Project #2: Address the doctor capacity crisis by enhancing doctors' ability to manage 30% more patients without compromising quality or risking burnout.Project #3: Create a marketplace that serves as the primary access point for healthcare services across various channels.

Netguru is an esteemed partner in the realm of digital commerce, dedicated to assisting renowned brands in modernizing their B2B solutions, marketplaces, and retail ecosystems. Since its inception in 2008, Netguru has empowered businesses with state-of-the-art technology, AI-driven personalization, and exemplary engineering and design teams. As a certified B Corporation®, we have earned the trust of leading brands such as IKEA, VW, OLX, Delivery Hero, Żabka, Wolt, Careem, and Vinted.Experience Freelancing with NetguruAs a Netguru Freelancer, you have the flexibility to choose the projects that resonate with you. You control your schedule, work environment, and how you approach your tasks.We align your skills with suitable projects, providing access to a variety of opportunities across different industries. This approach not only enhances your experience but also broadens your skill set.Moreover, our freelancers can engage in full-time collaboration and become integral members of our team.Are you ready to make a difference? Join us at Netguru, and let’s craft beautiful software together.We are currently seeking Senior Business Analysts for three distinct projects:1. Claim Center - Responsible for analyzing the functionalities of the Claim Center, including FNOL, exposure/reserve creation, integration with external systems for information exchange, document production analysis, and claim payments.2. Billing Center - Tasked with preparing analyses based on key business processes such as invoicing, agency/direct billing, payment allocation, delinquency management, refunds, account billing, integration with payment providers, general ledger integration, and document production systems, including multicurrency aspects.3. Policy Center - Focused on analyzing topics such as product models in APD, sales pathways in the submission process, underwriting issues, rating, policy issuance, post-sales transactions (MTA, renewals, rewrites, cancellations), managing customer contacts and accounts, and integration with both internal and external systems.Project Start Date: FebruaryFreelance Assignment Details: Full-time, approximately 12 months with potential for extension, B2B contract.Compensation Range: 120 - 140 PLN/hourWorking Hours: CETWork Location: Europe

At Valtech, we are an experience innovation company, recognized as a trusted partner to some of the world’s most esteemed brands. We are committed to providing our team with ample growth opportunities, a values-driven culture, and international career prospects that empower you to shape the future of experience.The OpportunityJoin us at Valtech, where an environment fostering continuous learning, meaningful impact, and professional growth awaits you. As a Senior Salesforce Engineer, you will be at the forefront of pioneering new digital solutions, challenging conventional thinking, and building the next generation of customer experiences.

Netguru is a pioneering partner in the realm of digital commerce, dedicated to assisting renowned brands in the modernization of B2B solutions, marketplaces, and retail ecosystems. Since 2008, we have empowered businesses through innovative technology, AI-driven personalization, and exceptional engineering and design teams. As a certified B Corporation®, we have built a reputation as a trusted partner for major brands such as IKEA, VW, OLX, Delivery Hero, Żabka, Wolt, Careem, and Vinted.Freelancing at Netguru: Your Flexible PathAt Netguru, our freelancers enjoy the liberty to choose their projects, working conditions, and schedules. We align you with opportunities that suit your expertise, allowing you to gain diverse experiences and develop new skills across various industries. Not only can you work on exciting projects, but you can also engage in full-time collaborations, becoming a valued member of our team.Are you ready to leave your mark? Join Netguru, and together we can create remarkable software.We are currently seeking a Senior Fullstack Engineer with proven experience in implementing Instagram Login independently.Compensation: up to 160 PLN/h (on a B2B contract)Engagement Level: Full-timeWorking Hours: CETStart Date: 31.01.2026Project Duration: 2 monthsKey Responsibilities:Overseeing the 'App Review' Process: Managing the complete verification cycle with Meta, including creating necessary screencasts and writing scope justifications to ensure app approval for Live access.Setting Up Meta Ecosystem: Correctly configuring the application environment in the Meta for Developers console, identified as a primary risk area by the client.OAuth Strategy & Implementation: Implementing the 'Login with Instagram' flow to securely retrieve specific influencer data points for profiling.Providing Technical Guidance: Serving as the subject-matter expert to navigate Meta's stringent policies and mitigate application rejection risks.Required Qualifications:Fluency in Polish and English.Experience with OAuth 2.0.Familiarity with Instagram Graph API.Experience with Meta App Review.Preferred Skills:Knowledge of Passport.js / NextAuth.js / OmniAuth (based on tech stack).Understanding of JWT (JSON Web Tokens).Experience with OpenID Connect (OIDC).Familiarity with Facebook Login Kit.Basic knowledge of GDPR compliance.Perks:What We Offer You:100% remote work flexibility.

Flying Bisons is a premier Digital Consulting and Delivery company situated in the vibrant city of Warsaw, Poland. Our mission is to empower our clients to Unleash Digital Potential™. We excel in discovering, defining, designing, and developing top-tier digital products that yield impactful business results for our clients, creating outstanding digital experiences for millions worldwide.What sets us apart is our comprehensive end-to-end process that equips us to tackle every challenge with the assurance of achieving optimal results. Our areas of expertise encompass Research, Digital Strategy, Branding, Content Creation (Written, Photos, Videos), Product Design, Web & Mobile Development, Data Analytics, and AI.Become part of our dynamic team of 120 professionals and collaborate in crafting groundbreaking products and exhilarating experiences for notable brands(such as Mercedes AMG, IKEA, KFC, eObuwie, Żabka, Sanofi, Zain) and innovative startups (like Booksy, Nethone, Telemedi, or DevSkiller)!We are in the process of building a curated network of talented freelance Backend Developers to engage for both current and future projects. When you apply to join our freelancer base, your application will be assessed and kept on file. You may not be contacted immediately, but once a project aligns with your expertise, you will receive an invitation to participate, allowing you to accept or decline based on your availability. If you're interested in joining our talent pool, please submit your CV. We will reach out as soon as a fitting opportunity becomes available.Are you a self-motivated and reliable professional? If so, we are eager to hear from you!