Senior Fullstack Developer
Reaktor's tech community is looking for an experienced Senior Fullstack Developer to join one of our Business Units in Helsinki.
If you are comfortable working across modern web applications, backend services and production systems, enjoy solving ambiguous problems with clients, and are curious to work in a low-hierarchy environment, you might just be what we’re looking for.
You will support clients across a range of digital product, platform and service domains. The exact client context may vary from focused product teams to large international companies working on high-traffic, business-critical services.
Many of our clients are technically mature and expect a high level of expertise from our consultants. This means you will need to be hands-on, pragmatic and comfortable helping both the client and the team make good technical decisions.
Your daily tasks may include:
Building and improving modern web applications, backend services, APIs and data models
Working across frontend, backend and infrastructure depending on the needs of the client project
Helping clients choose suitable technologies, architecture and delivery approaches
Contributing to cloud environments, CI/CD pipelines, deployments and production quality
Debugging, testing, monitoring and improving production-grade systems
Working on products or tooling related to customer-facing services, internal platforms, identity, martech, customer support, analytics, online stores, integrations, developer tooling or SDKs
Collaborating directly with client tech teams, business stakeholders, designers, product people and other disciplines
Clarifying ambiguous requirements and turning them into working software
Taking responsibility for delivery while making sure the team is supported and no one is left behind
Using modern development practices, including openness to AI-assisted development tools and workflows
To thrive in this position, you’ll need:
Must-haves
Strong experience in modern frontend development, for example with TypeScript, , React or comparable technologies
Strong experience in backend service development, for example with Node.js, Java, Kotlin, Scala, Clojure, Python or comparable technologies
Experience building, shipping and improving production-grade digital products
Comfortable working across the full delivery lifecycle, from implementation to testing, deployment and production quality
Understanding of cloud environments, CI/CD, deployments and how production systems are operated
Ability to work directly with clients, stakeholders and other disciplines in a senior, consultative role
Strong problem-solving skills and the ability to bring clarity to ambiguous product or technical situations
A hands-on mindset - you are technically credible, actively contribute to the work and help the team move forward
Fluent verbal and written English skills to collaborate in an international environment
We do not have a hard requirement around years of experience, but we have noticed that this level of fullstack, client-facing and production ownership usually takes several years of professional experience to build.
Nice-to-haves
Experience from customer-facing digital products, online services, ecommerce, subscriptions, internal platforms, analytics, martech or similar product domains
Experience with high-traffic or business-critical production systems
Deeper experience with platform engineering, infrastructure-as-code or DevOps practices
Experience with customer-facing products, internal tools, integrations, SDKs or developer tooling
Familiarity with mobile development or React Native
Finnish language skills
Adaptability
Willingness to work in a hybrid setup. This means balancing office, client premises and remote work depending on the client project and team needs.