Senior JavaScript Engineer (m/f/d) – Focus on Web Performance & SDK

Raisin is the world’s leading platform for savings and investment products. Founded in 2012, the FinTech connects consumers with banks in the EU, the UK and the US. This gives consumers better interest rates and banks a diversified form of refinancing. Our vision is to offer savings and investments without barriers and thus open up the global 160 trillion euro market. Raisin currently employs more than 800 people from over 75 countries worldwide. Today, the platform holds over 80 billion euros in assets from more than one million investors which have accrued over 5 billion euros in returns. Team The US Payments & Partner Operations (PPO) team owns the core money-movement stack for the Raisin US’ platform: ACH payment initiation, reconciliation, returns, and cut-off scheduling, plus the customer accounts lifecycle — bank linking, fraud signal integration, and identity verification. Beyond payments, the team manages the B2B layer: onboarding and configuring Deposit-taking Banks, service banks, and custodians, including their user/role management. It also covers invoicing data pipelines for Deposit taking banks, escheatment workflows for dormant accounts and visibility for operations and customer support through our internal platform portal. Your Responsibilities * Own and deliver features and bug fixes end-to-end with minimal guidance. * Identify and address bottlenecks in the team's delivery flow, from design to deployment. * Utilize AI tools intensively for increasing our ability and pace to deliver software. * Promote best practices around our core stack. * Transfer knowledge proactively, lead by example in learning and mentoring. * Contribute to improving how we program, test, review, and ship code. * Flag process gaps and propose pragmatic improvements. * Elevate engineers in growing their technical skills. * Provide constructive code review and solve complex problems together. * Quickly build practical depth in PPO's domains. * Contribute meaningfully to new feature design and implementation. * Bring engineering perspective into domain discussions alongside other team roles like Product Manager, Tech Lead and Engineering Lead. Your Profile We are looking for a versatile Senior Full-Stack Engineer with a deep, rock-solid foundation in the .NET and SQL Server ecosystem, who has the architectural maturity to adapt to other layers and the drive to learn the rest of our stack. Required: * Designing, optimizing, and maintaining robust enterprise APIs using .NET Web API. * Building and structuring web applications with .Net * Strong relational database design, complex querying, and performance tuning in SQL Server. * Design Patterns: A deep understanding of SOLID principles and a proven track record of writing Clean Code. * Structural Strategy: Practical experience working within modern architectural patterns, specifically Clean / Onion Architecture, to keep codebases decoupled and testable. * Fast Learner: You don't mind stepping out of your .NET comfort zone to touch a React component or a Go microservice. * Problem Solver: Highly analytical with a strong focus on detail and quality. * Collaborator: A team-first peer who thrives on open communication and cross-layer collaboration. Desired: * Experience building user interfaces with React JS, JavaScript, and HTML, accompanied by testing tools like Jest or React Testing Library. * Exposure to, or curiosity about environments like Node.js, GoLang, or Java / Spring Boot, and building APIs  * Experience with GraphQL. * Working knowledge or conceptual familiarity with MongoDB or NoSQL Databases * Familiarity with NUnit for automated testing * Familiarity with secure authentication via OAuth and ASP.NET Identity.   Join our mission, join our team – and grow with us! At Raisin, we care about each other and it is one of our top priorities to foster an open and caring environment in which everyone feels welcome and comfortable. Our culture is strongly driven by our ambitious team, which connects more than 75 different nationalities. As part of our team, you will benefit from: Raisin SE Spain * Employee Development Budget of €2,000 and four full training days per year. * Flexible working hours, home office and 28 vacation days. Raisin Applicant Privacy Policy [https://www.raisin.com/corporate/raisin-applicant-privacy-policy/] We value diversity and the unique experiences each individual brings. If you’re excited about this role but don’t meet every requirement, we still encourage you to apply. We are an equal opportunity employer and are committed to creating an inclusive environment for everyone, regardless of race, colour, ancestry, religion, sex, national origin, sexual orientation, age, citizenship, marital status, disability, or gender identity.

Raisin is the world’s leading platform for savings and investment products. Founded in 2012, the FinTech connects consumers with banks in the EU, the UK and the US. This gives consumers better interest rates and banks a diversified form of refinancing. Our vision is to offer savings and investments without barriers and thus open up the global 160 trillion euro market. Raisin currently employs more than 800 people from over 75 countries worldwide. Today, the platform holds over 80 billion euros in assets from more than one million investors which have accrued over 5 billion euros in returns. Team The US Payments & Partner Operations (PPO) team owns the core money-movement stack for the Raisin US’ platform: ACH payment initiation, reconciliation, returns, and cut-off scheduling, plus the customer accounts lifecycle — bank linking, fraud signal integration, and identity verification. Beyond payments, the team manages the B2B layer: onboarding and configuring Deposit-taking Banks, service banks, and custodians, including their user/role management. It also covers invoicing data pipelines for Deposit taking banks, escheatment workflows for dormant accounts and visibility for operations and customer support through our internal platform portal. Your Responsibilities * Own and deliver features and bug fixes end-to-end with minimal guidance. * Identify and address bottlenecks in the team's delivery flow, from design to deployment. * Utilize AI tools intensively for increasing our ability and pace to deliver software. * Promote best practices around our core stack. * Transfer knowledge proactively, lead by example in learning and mentoring. * Contribute to improving how we program, test, review, and ship code. * Flag process gaps and propose pragmatic improvements. * Elevate engineers in growing their technical skills. * Provide constructive code review and solve complex problems together. * Quickly build practical depth in PPO's domains. * Contribute meaningfully to new feature design and implementation. * Bring engineering perspective into domain discussions alongside other team roles like Product Manager, Tech Lead and Engineering Lead. Your Profile We are looking for a versatile Senior Full-Stack Engineer with a deep, rock-solid foundation in the .NET and SQL Server ecosystem, who has the architectural maturity to adapt to other layers and the drive to learn the rest of our stack. Required: * Designing, optimizing, and maintaining robust enterprise APIs using .NET Web API. * Building and structuring web applications with .Net * Strong relational database design, complex querying, and performance tuning in SQL Server. * Design Patterns: A deep understanding of SOLID principles and a proven track record of writing Clean Code. * Structural Strategy: Practical experience working within modern architectural patterns, specifically Clean / Onion Architecture, to keep codebases decoupled and testable. * Fast Learner: You don't mind stepping out of your .NET comfort zone to touch a React component or a Go microservice. * Problem Solver: Highly analytical with a strong focus on detail and quality. * Collaborator: A team-first peer who thrives on open communication and cross-layer collaboration. Desired: * Experience building user interfaces with React JS, JavaScript, and HTML, accompanied by testing tools like Jest or React Testing Library. * Exposure to, or curiosity about environments like Node.js, GoLang, or Java / Spring Boot, and building APIs  * Experience with GraphQL. * Working knowledge or conceptual familiarity with MongoDB or NoSQL Databases * Familiarity with NUnit for automated testing * Familiarity with secure authentication via OAuth and ASP.NET Identity.   Join our mission, join our team – and grow with us! At Raisin, we care about each other and it is one of our top priorities to foster an open and caring environment in which everyone feels welcome and comfortable. Our culture is strongly driven by our ambitious team, which connects more than 75 different nationalities. As part of our team, you will benefit from: * Employee Development Budget of €2,000 and four full training days per year. * Flexible working hours, home office and 30 vacation days. * A company pension scheme (Betriebliche Altersvorsorge), which we support with 20%. * Enjoy more than 50+ different sports with Urban Sports Club: We subsidize your membership with more than €20 per month.  * Do you miss being in the office? The Deutschland Ticket gets you there, which we subsidize with €25 per month. * Love cycling? With JobRad, lease the bike of your choice and enjoy tax savings, plus Raisin covers your monthly insurance costs. * Hungry all the time? Snacks, daily fresh fruit as well as drinks provided at the office. Raisin Applicant Privacy Policy [https://www.raisin.com/corporate/raisin-applicant-privacy-policy/] We value diversity and the unique experiences each individual brings. If you’re excited about this role but don’t meet every requirement, we still encourage you to apply. We are an equal opportunity employer and are committed to creating an inclusive environment for everyone, regardless of race, colour, ancestry, religion, sex, national origin, sexual orientation, age, citizenship, marital status, disability, or gender identity.