Jobs Kotlin

About Masthead Data

Masthead Data is a data observability and BigQuery cost optimization platform built on a zero-data-access architecture — we operate exclusively on audit logs and metadata, and never touch our customers' underlying data. That constraint is our core differentiator and shapes every engineering decision we make. We work with enterprise customers who manage millions of tables and care deeply about security, auditability, and doing more with less. We uncover hidden data issues in real-time and drive hundreds of thousands of dollars in monthly savings.

The Role

We're looking for a full-time remote Senior Backend Engineer to own significant parts of our platform end to end — from architecture through production. You'll work on systems that process large volumes of audit-log and metadata events, detect issues in production data environments, power our FinOps recommendations, and integrate deeply with GCP. This is a high-ownership role with real influence over technical direction.

What you'll do

• Design, build, and operate backend services in Kotlin (Spring Boot) running on GKE
• Work across our data pipeline: BigQuery, Pub/Sub, PostgreSQL, and GCP-native tooling
• Build and refine the systems behind our cost optimization and observability features
• Manage infrastructure as code with Terraform, and help evolve our multi-tenant, per-customer project architecture
• Uphold and extend our zero-data-access security model — least-privilege access, granular controls
• Contribute to architecture decisions, code reviews, and the technical growth of the team

What we're looking for

• Strong backend experience with Kotlin (or Java with a genuine willingness to move to Kotlin) and Spring Boot
• Hands-on experience running production workloads on Kubernetes, ideally GKE
• Ownership: you can take an ambiguous problem and drive it to a production result
• Solid grounding in GCP — BigQuery, Pub/Sub, IAM, and related services
• Comfort with infrastructure as code, particularly Terraform
• Experience with PostgreSQL and designing data-intensive backend systems
• A security-conscious mindset and appreciation for operating within tight data-access constraints

Nice to have

• Experience with data observability, FinOps, or cloud cost optimization
• Familiarity with multi-tenant SaaS architecture and cross-tenant isolation patterns
• Background working with enterprise customers and their security requirements

Why Masthead Data

You'll join a small, senior team solving genuinely hard problems where the architectural constraints are the interesting part. Your work will be visible to enterprise customers from day one, and you'll have room to shape both the product and how we build it.

Our Mission and Vision

At Solidgate, our mission is clear: to empower outstanding entrepreneurs to build exceptional internet companies. We exist to fuel the builders — the ones shaping the digital economy — with the financial infrastructure they deserve. To achieve that, we're on a bold path: to become the #1 payments orchestration platform in the world.

We believe the future of payments is shaped by people who think big, take ownership, and bring curiosity and drive to everything they do. That's exactly the kind of teammates we want on board.

Solidgate is part of Endeavor — a global community of the world's most impactful entrepreneurs. We're proud to be the first payment orchestrator from Europe to join — and to share our expertise within a network of outstanding global companies.

About the Team and Role

You'll join the Core team — the team responsible for the services that sit at the heart of Solidgate's payment processing. Core services define what a payment is, integrate with numerous internal services for correct routing, run antifraud checks, and process payments through providers, covering card payments as well as Apple Pay and Google Pay. This is the critical path for every payment on the platform, so the team's work directly defines the reliability and speed of the whole system.

The team is actively growing new functionality, supporting existing services, working down technical debt, and maintaining an SLO of 99.99%+ across all of its services. The stack is built around high-load, low-latency requirements: a microservices architecture with Kotlin as the primary language, Protobuf RPC over Buf/Connect, PostgreSQL as the main database, and Kafka for asynchronous processing, with fully automated production deployments and an advanced monitoring and observability setup. Infrastructure is continuously improved by a dedicated platform team, with IaC ensuring transparent, reproducible, and scalable management.

Your team — Product Manager, Tech Lead (Backend), three Backend Software Engineers (Senior), one Frontend Software Engineer (Middle), AQA Engineer, and System Analyst.

What you'll own

Your focus will be on:

• taking part in product decisions across the full development lifecycle
• designing and developing backend functionality for our products
• collaborating with other teams to build reliable solutions for payment processing
• improving the performance, scalability, quality, and reliability of our systems

You'll grow from feature-level tasks toward owning a dedicated service or domain, taking part in the team's design and technical decisions.

You're a great fit if you have

• 3+ years of experience with Java and/or 1+ year with Kotlin
• Confident hands-on experience with SQL databases (PostgreSQL/MySQL)
• Experience designing reliable, scalable systems
• Experience with distributed systems
• Experience with cloud environments (AWS/GCP)
• Technical/computer science-related degree
• 2+ years of active hands-on use of AI tools

Nice to have

• Fintech experience and experience with high-load, complex systems
• Observability/Alerting tools (Prometheus, Grafana)
• Infrastructure as Code (Terraform)
• Message brokers (Kafka/SQS/RabbitMQ)

Why Solidgate?

High-impact role. You'll work at the very core of our payment processing — the critical path for every transaction, including Apple Pay, Google Pay, and card payments.

Great product. We've built a fintech powerhouse that scales fast. Solidgate isn't just an orchestration player — it's the financial infrastructure for modern Internet businesses. From subscriptions to chargeback management, fraud prevention, and indirect tax — we've got it covered. We hold financial licenses in key regions and are a direct Visa & Mastercard partner and sub-reseller (top 5 globally).

Massive growth opportunity. Solidgate is scaling rapidly — this role will be a career-defining move.

Top-tier tech team. Work alongside our driving force — a proven, results-driven engineering team that delivers.

Modern engineering culture. TBDs, code reviews, solid testing practices, metrics, alerts, and fully automated CI/CD.

💌 The Extras: 30+ days off, unlimited sick leave, free office meals, health coverage, and Apple gear to keep you productive. Courses, conferences, sports and wellness benefits — all designed for ideas, focus, and fun.

Tomorrow's fintech needs your mindset. Come build it with us.

🫂 Know top talent? We're always on the lookout. Refer someone for our role, and if they get hired, there's a bonus waiting for you — simple as that.

We're looking for a strong Senior Full-Stack Developer to join an enterprise project for one of our long-term clients. We already have several developers successfully working on this project.

📌 Project

A web-based platform for German leasing companies that supports and automates their core business processes.

🚀 Senior Full-Stack Developer (Kotlin / Java / React)

📍 EU only (business trip to Germany for 3–4 days every 6 months)

🗣 English: C1

✅ Requirements

6+ years of software development experience

Strong Kotlin & Java

Strong React

Experience with PostgreSQL and/or MongoDB

CI/CD & automated testing

Experience with AI-assisted development

Strong software engineering and problem-solving skills

⭐ Nice to have

Node.js

💼 Responsibilities

Develop and enhance full-stack applications

Build scalable backend services with Kotlin & Java

Develop modern React features

Improve architecture and optimize existing modules

Collaborate with Product, QA, and DevOps teams

Participate in code reviews

Мобільний застосунок футбольних прогнозів: внутрішня валюта, турніри, лідерборди, live-скори. Дизайн затверджений у Figma, бекенд робить окрема людина, на старті працюєте з моками по контракту API.

Треба буде:

• зібрати застосунок на Kotlin Multiplatform + Compose Multiplatform під Android та iOS
• REST + WebSocket: live-оновлення рахунків, reconnect, щоб список не стрибав
• пуші, підписки через RevenueCat, офлайн-стани
• верстку екранів закриває окрема людина, з вас архітектура, мережа, стан

Кого шукаємо:

• 3+ роки Android/Kotlin, хоча б один KMP-проєкт, який дійшов до стора
• є застосунок у Google Play чи App Store, який можна відкрити і подивитись
• був досвід з live-даними на екрані: черга подій, дублікати, reconnect
• анімації та Compose Canvas — плюс, у продукті будуть міні-ігри

Формат: той самий, що в описі вище — проєктна робота, remote, фікс за етап після приймання, старт у серпні. Орієнтир $2000-2500/міс.

Відгук: слово «офсайд» + лінк на застосунок у сторі й одне речення, що там було найскладнішим.

Далі: тестове до 4 годин, дзвінок з розбором, старт.

Phoenix Games is an innovative technology company building next-generation iGaming and Web3 products for a global audience. We create high-performance gaming platforms powered by AI, blockchain, cloud technologies, and modern mobile solutions.

We're looking for Middle and Senior Android Developers to help build world-class mobile applications with a strong focus on performance, security, and user experience.

What You'll Do

• Develop and maintain native Android applications using Kotlin.
• Build scalable, maintainable, and high-performance mobile solutions.
• Collaborate with Product Managers, Designers, Backend Engineers, and QA throughout the development lifecycle.
• Integrate REST APIs, WebSockets, and third-party SDKs.
• Optimize application performance, stability, and battery usage.
• Write clean, testable, and maintainable code following modern Android best practices.
• Participate in code reviews and architectural discussions.
• Continuously improve the application's user experience and performance.

Tech Stack

• Kotlin
• Android SDK
• Jetpack Compose
• MVVM
• Coroutines & Flow
• Retrofit
• Room
• Hilt / Dagger
• Firebase
• REST APIs
• WebSockets
• Git
• CI/CD
• Android Studio

Requirements

Middle

• 3+ years of commercial Android development experience.
• Strong knowledge of Kotlin.
• Experience with Android SDK and Jetpack libraries.
• Experience integrating REST APIs.
• Understanding of MVVM architecture.
• Familiarity with Git.
• Upper-Intermediate English or higher.

Senior

• 5+ years of commercial Android development experience.
• Expert knowledge of Kotlin and modern Android architecture.
• Strong experience with Jetpack Compose.
• Experience designing scalable mobile applications.
• Strong understanding of app performance optimization and memory management.
• Experience with dependency injection (Hilt/Dagger).
• Experience with CI/CD pipelines for mobile applications.
• Ability to mentor developers and participate in architectural decisions.
• Upper-Intermediate English or higher.

Nice to Have

• Experience with Firebase services.
• Knowledge of WebSockets and real-time applications.
• Familiarity with Web3 or blockchain technologies.
• Experience with automated testing (JUnit, Espresso).
• Experience publishing applications to Google Play.

What We Offer

• Fully remote work from anywhere in Europe.
• Long-term B2B cooperation.
• Competitive salary paid in EUR or USD.
• Annual salary reviews.
• Performance-based bonus program.
• Annual company bonus.
• 25 paid vacation days.
• Paid sick leave.
• Flexible working hours.
• Home office budget.
• Laptop or equipment allowance.
• Learning & development budget for courses, certifications, books, and conferences.
• English language lessons.
• Private health insurance.
• Mental health support program.
• Sports and wellness compensation.
• Team-building activities and international company retreats.
• Opportunity to work on cutting-edge AI, Web3, blockchain, and mobile technologies.
• Clear career growth opportunities within a fast-growing international product company.

Why Join Phoenix Games?

At Phoenix Games, you'll build modern Android applications from the ground up using the latest technologies and best engineering practices. You'll work alongside a talented international team, influence technical decisions, and help create products enjoyed by users around the world.

If you're passionate about Android development and want to build innovative mobile products with real impact, we'd love to hear from you.

We are looking for an experienced Senior Mobile Developer to become a key member of our product team and help shape the future of our mobile platform.

About the Product:

The project is under NDA.

It is a professional GPS navigation and route planning platform designed for enterprise customers. The solution provides advanced mapping, routing, navigation and geospatial capabilities for business-critical operations. It integrates with leading mapping providers and serves international customers across logistics, transportation, public services, emergency response and other industries where reliable navigation is essential. (LinkedIn)

The first milestone is to modernize the existing iOS application and successfully release it to the App Store. After that, you will play a leading role in building a shared Kotlin Multiplatform codebase for both iOS and Android.

Responsibilities:

• Maintain and improve the existing iOS application.
• Prepare and publish production releases to the App Store.
• Participate in architecture and technical decision-making.
• Develop a shared Kotlin Multiplatform codebase.
• Collaborate with an international product team.
   

Requirements:

Must Have;

• 5+ years of commercial mobile development experience.
• Strong expertise in Swift and iOS SDK.
• Hands-on experience publishing applications to the Apple App Store.
• Experience with App Store Connect, Apple Developer Console and TestFlight.
• Solid understanding of modern mobile architectures (MVVM, Clean Architecture, etc.).
• Commercial experience with Kotlin.
• Experience with or strong interest in Kotlin Multiplatform.
• Upper-Intermediate (B2) English or higher.
   

Nice to Have:

• Kotlin Multiplatform (KMP/KMM).
• Android development experience.
• Jetpack Compose.
• German language skills.
• Experience with mapping, navigation or GPS products.

• Startup or product company background.

   

We Offer:

• Long-term collaboration.
• Fully remote position (Ukraine).
• Opportunity to influence product architecture.
• Work on an international software product.

• Small, highly efficient team with fast decision-making.

   

When applying, please include:

• Links to App Store applications you've worked on.
• A brief description of your role in the release process.
• Your Kotlin / Kotlin Multiplatform experience.
• Your English proficiency level.
• Whether you speak German.

We're looking for a Senior Kotlin Backend Developer to join an international team building scalable backend solutions. You'll take ownership of features from design to production, contribute to architectural decisions, mentor teammates, and communicate directly with the client in English.
 

Requirements

• 5+ years of backend development experience
• Strong commercial experience with Kotlin
• Solid understanding of JVM fundamentals (concurrency, memory management, garbage collection)
• Experience with Spring Boot (or Ktor / Micronaut)
• Strong knowledge of REST API design
• Experience with relational and/or NoSQL databases (PostgreSQL, MySQL, MongoDB, etc.)
• Hands-on experience with ORM frameworks such as JPA, Hibernate, or Exposed
• Experience writing unit and integration tests using JUnit and MockK
• Good understanding of Clean Architecture, SOLID principles, Git, CI/CD, and code review practices
• Experience with AI-assisted development tools such as GitHub Copilot, Cursor, Claude, or similar
• Upper-Intermediate or higher English (direct communication with clients)
   

Responsibilities

• Design, develop, and maintain backend services using Kotlin
• Own features end-to-end, from technical discussions to production deployment
• Build clean, maintainable, and well-tested code
• Participate in architecture and system design decisions
• Review code and mentor other engineers
• Collaborate directly with clients and cross-functional teams
• Continuously improve development processes and engineering quality
   

Nice to Have

• Experience with microservices architecture
• Docker and Kubernetes
• Cloud platforms (AWS, GCP, or Azure)
• Messaging systems (Kafka, RabbitMQ)
• Redis or other caching technologies