Senior Full Stack Developer – TypeScript & Java/Kotlin

key.dev; United States; Remote; USD 120,000 - 180,000; Full time

Benefits offered by this job

25 days annual leave

Health insurance

Multisport benefit

Career and skills development

Job summary

key.dev is seeking a seasoned full-stack engineer to build and operate production software across the frontend and backend for international client projects. You’ll take work from design through deployment, contribute to technical decisions, and help improve the infrastructure that supports the team’s services.

Responsibilities include developing backend services and accessible web apps, owning features end-to-end, writing maintainable code with automated tests, and collaborating in an agile

Qualifications

• 5+ years building and operating production full-stack systems.
• Strong web fundamentals: HTML, CSS, and JavaScript or TypeScript; framework experience (React/Preact/Vue).
• Backend experience with Java or Kotlin and frameworks like Ktor or Spring Boot.
• Working knowledge of SQL databases and schema design; CI/CD and cloud experience.
• Fluent English; based in Bulgaria or the EU and eligible to work there without visa sponsorship.

Responsibilities

• Develop backend services and accessible, performant web applications.
• Own features through design, implementation, deployment, and operation.
• Write maintainable code and add automated tests.
• Contribute to architecture discussions and solve multi-tier technical problems.
• Help maintain infrastructure and observability tools.
• Collaborate with colleagues in an agile setting and share technical knowledge.

Skills

HTML, CSS, JavaScript/TypeScript

React/Preact/Vue

Tools

Ktor

Spring Boot

Job description

Role overview

Build and operate production software across the frontend and backend for international client projects. You’ll take work from design through deployment, contribute to technical decisions, and help improve the infrastructure that supports the team’s services.

Responsibilities

• Develop backend services and accessible, performant web applications.
• Own features through design, implementation, deployment, and operation.
• Write maintainable code and add automated tests.
• Contribute to architecture discussions and solve multi-tier technical problems.
• Help maintain infrastructure and observability tools.
• Collaborate with colleagues in an agile setting and share technical knowledge.

Requirements

• At least five years of experience building and operating production systems across the full stack.
• Strong web fundamentals in HTML, CSS, and JavaScript or TypeScript, plus experience with a framework such as React, Preact, or Vue.
• Backend experience with Java or Kotlin and a framework such as Ktor or Spring Boot.
• Working knowledge of SQL databases and schema design.
• Experience with automated testing and a major cloud provider, as well as CI/CD pipelines.
• Fluent written and spoken English; applicants must be based in Bulgaria or the EU and eligible to work there without visa sponsorship.

Nice to have

• Experience with microservices, self-contained systems, Domain-Driven Design, or server-side rendering.
• Familiarity with observability, Kafka or SQS, and Infrastructure as Code tools such as Pulumi, AWS CDK, or Terraform.
• German language skills; Playwright or similar end-to-end testing experience.

Benefits and work setup

Full-time work with remote or home-office options.

• 25 days of annual paid leave
• additional health insurance
• a multisport benefit
• opportunities for career and skills development