Skip to content
Frontend Engineer

Frontend Engineer

Senior Software Engineer

Appfire

Sofia

Apply on the employer's site

Role description

At Appfire, we believe that great work happens when people get to choose how they work. After 20 years of creating software that empowers teams to break silos and collaborate seamlessly, we've learned that one size does not fit all. We're a team of 800+ employees, working remotely across 28 countries. Our flagship products include: JXL, Comala Document Management, 7Pace Time Tracker, Jira Misc Workflow Extensions, and BigPicture.

Here you can read some of our customer stories: https://appfire.com/resources/resource\-library/customer\-stories

About the role:
Appfire is looking for a
Senior Java Software Engineer
to help evolve a modern, cloud-based SaaS platform. You'll design new backend functionality, optimize existing services, and support systems used by thousands of tenants. This role reports to the Senior Manager of Engineering and works cross-functionally with product, UX, and frontend partners to deliver reliable, well-tested SaaS solutions.

You can choose to work remotely from anywhere in Bulgaria.

What you'll do:

  • Designing and implementing new functionalities while maintaining and optimizing existing ones.
  • Ensuring high code quality through rigorous testing (unit, integration) and peer code reviews.
  • Collaborating with Product Owners, UX/UI designers, and frontend teams.
  • Solving performance-related challenges to ensure system stability and speed.
  • Contributing to technical discussions and helping the team solve production issues.
  • Actively utilizing AI-assisted developer tools (e.g., Cursor, Claude Code) to boost daily productivity and participating in the technical implementation of AI-driven product features.

Technical Highlights:

  • Add your value to a complex yet well-designed application, having over 100 modules and fully-fledged Domain-Driven Design (ubiquitous language, aggregates, domain events etc.)
  • Practice your craftsmanship in good design (clean code, SOLID, Inversion of Control) and in various architectures (hexagonal, event-driven, pipes&filters, modular monoliths, microservices and more)
  • Thoroughly test what you build: with unit, integration and e2e tests (Spock, JUnit, Mockito, AssertJ, REST Assured, WireMock, Testcontainers, Cypress)
  • Learn our advanced cloud (SaaS) architecture: serving thousands of tenants (multitenant architecture), continuously monitored and profiled (ELK, async-profiler), and with state of the art release process (feature flags, canary releases). We use AWS and GCP. Help us advance our cloud architecture further
  • Practice other cool approaches and tools like reactive programming, Event Sourcing, Apache Kafka or Redis
  • Enhance your engineering workflow by adopting state-of-the-art AI tools for code generation, refactoring, and debugging, while working on cutting-edge AI integrations
  • Feel safe with our extensive CI process that automatically runs unit, integration, e2e, architecture, migration and performance tests on your commit

What you'll need:

  • Solid Java Foundation:
    Strong practical knowledge of Java, Spring, Hibernate, and SQL.
  • Clean Code & Patterns:
    A good understanding of SOLID principles and common design patterns to keep the codebase maintainable.
  • AI & Modern Tooling:
    Hands-on experience working with AI coding assistants (like Cursor) and an eagerness to implement modern AI solutions (e.g., LLM integrations, RAG) into the product.
  • Testing & Tools:
    Proficiency in JUnit/Spock, Git, Maven, and Docker.
  • Production-Ready Mindset:
    Experience in evolving and scaling established systems (beyond just greenfield projects) and a focus on long-term code maintainability.
  • Performance Awareness:
    Ability to use profiling tools and a focus on writing efficient code that performs well under load.
  • Cloud Basics:
    Understanding of SaaS architecture and cloud environments (AWS or GCP).

Beyond the resume skills that match our culture and this role:

  • You are dedicated to elevating client and co-worker experiences, knowing that exceptional work centers on serving others.
  • You adapt swiftly to new business demands, understanding that change fuels collective and individual growth.
  • You excel in communication, effectively connecting in remote/hybrid environments using tools like Slack, Zoom, and G Suite and through occasional in-person events.
  • You have exceptional coaching, mentoring, and people development skills.

What we offer:

  • Equity - Every Appfire team member is eligible for company equity, fostering a true sense of ownership and connection to our growth
  • Paid time off - 25 paid days off regardless of your years of tenure. Increases to 30 days of annual leave per year after 5 years of employment 24 hours of paid volunteer time to engage in meaningful activities outside of work
  • Training and personal development - Grow with Appfire University — our custom, on-demand learning platform designed to support your continuous development
  • Health insurance - Private health insurance through UNIQA, fully paid by the company
  • Multisport Card - The card is fully covered by Appfire
  • Transport Card - Sofia City Transport Card, fully paid by Appfire, providing access to all modes of public transportation within the city
  • Food vouchers - Pre-paid Pluxee lunch card with a monthly budget of 102,26 EURO
  • Baby Bonus - To celebrate new additions to the family, employees receive a one-time net bonus of 511 EURO upon the birth of a child
  • Volunteering - 3 fully paid days each year to participate in Appfire Town, our Corporate Social Responsibility (CSR) program supporting local communities
  • Flexibility - The role is fully remote within Bulgaria, with the option to work from our Sofia office.

Market recognition
Appfire has been consistently recognized for company growth, culture, corporate social responsibility, and product excellence and has been included among the Deloitte Technology Fast 500, Inc. Best Workplaces, BuiltIn Best Places to Work, and Inc. 5000. Learn more about our accomplishments, which would not be possible without our team members, partners, and customers: https://appfire.com/awards.

Equal Employer Opportunity (EEO)
Appfire is an equal opportunity employer and does not discriminate based on race, color, religion, sex (including pregnancy), sexual orientation, gender identity or expression, national origin, age, disability, genetic information, marital status, veteran status, or any other protected characteristic as defined by applicable law. Our commitment extends to all employment practices, including recruitment, hiring, training, promotion, compensation, benefits, and termination.

This is a saved copy of a posting published elsewhere. Postings get taken down without notice — check the employer's site before applying. mentors.coach is not the hiring party.

Frontend Engineer

Junior Software Engineer

Amusnet

Sofiafulltime

Apply on the employer's site

Role description

Amusnet is a leading provider recognized for offering best-performing products and innovative solutions in gaming globally. With a portfolio of 300+ casino games, our company delivers engaging online entertainment across 2,000+ websites in 35+ markets. The dedication to innovation and technology also extends to the production of premium slot cabinets, where our games seamlessly integrate with cutting-edge hardware solutions. We continue to expand our network of offices, and our team now consists of 1,300+ industry professionals. As we grow, we're looking for Junior Software Engineer!

C++ runs in every system we deploy. We utilize it everywhere - from high-performance game rendering engines, through embedded devices, to distributed systems in the cloud. Join us and turn ideas into reality, from concept to finished product.

THE PERFECT TEAM MEMBER IS INSPIRED TO:

  • Participate in the development of software using C++
  • Work in Linux environment
  • Research and integrate third-party libraries APIs
  • Implement communication with various hardware devices
  • Ship new products from scratch in a high-growth, evolution-first environment
  • Collaborate with a team of experts in the field, to integrate and develop the optimal solutions

THE SKILLS THAT WILL GRAB OUR ATTENTION:

  • Experience in software engineering using C++14 and newer
  • Excellent command of C++ STL
  • Deep understanding of object-oriented design and programming
  • Good knowledge of various Design Patterns
  • Understanding the implementation of the most common data structures
  • Motivation to solve complex technical challenges
  • Strong interpersonal and communication skills, possessing a deep sense of project ownership
  • Strong attention to detail and great debugging skills
  • Highly motivated personality, striving for continuous improvement

SKILLS CONSIDERED AS AN ADVANTAGE:

  • SQL
  • REST principles
  • Linux operating system and shell scripting
  • Event driven programming
  • Experience with developing network applications
  • Experience with CI/CD tools

THE REASONS TO JOIN OUR TEAM:

  • Excellent remuneration package
  • Performance-based bonuses
  • Private health insurance
  • Card for Public Transportation
  • Multisport card
  • Corporate discounts
  • Parking – early bird option
  • 25 days of annual paid leave
  • Performance review process
  • Internal & external training programs
  • Team buildings & local company events
  • Work-life balance
  • Inspiring & supportive colleagues
  • Culture that encourages creativity & talent

If you are interested, please send us your CV.

All applications will be treated strictly confidential.

Only short-listed candidates will be contacted.

Thank you for applying!

This is a saved copy of a posting published elsewhere. Postings get taken down without notice — check the employer's site before applying. mentors.coach is not the hiring party.

Frontend Engineer

Android Developer

A1 Bulgaria

Sofiafulltime

Apply on the employer's site

Role description

Strength. Care. Growth
Did you know that A1 Bulgaria is working on international projects as well?

Our wide portfolio has long past the telecom services, and we are now offering digital solutions to millions of corporate, public, and private customers.

State-of-the-art technology, the latest innovations, and extremely talented professionals in various areas help us deliver the best-in-class products, services, and customer experience.

You’ll know A1 Bulgaria is the right place for you if you are driven by:

  • Opportunities to learn and build your career.
  • Meaningful work in a stable and fast-paced company.
  • Diversity of people, projects, and platforms.
  • A supportive, fun, and inspiring place to work.

Would you like to join us?
Metodi Mladenov
is looking for a new team member.
Join our team as an Android Developer and help build the next generation of the A1 XploreTV platform, developing high-performance Android TV and Set-Top Box applications for millions of users.

Your Daily Routine Would Include

  • Build and maintain high-performance features for the A1 XploreTV Android TV application and custom STB launcher using Kotlin and Java.
  • Drive the migration of legacy views to Jetpack Compose, ensuring smooth animations and rendering optimized for TV hardware and D-pad navigation.
  • Leverage Kotlin Coroutines and Flow for efficient, asynchronous state management and fluid user experiences.
  • Implement robust data-fetching layers using GraphQL to communicate with our high-scale backend services
  • Work closely within an agile Android team collaborating also with QA automation engineers, and Business Analysts to deliver clean, maintainable code.
  • Participate in code reviews, architectural discussions, and hardware-specific optimizations (including memory management and lazy loading for large content catalogs).

We’ll know you can make it if you have:

  • 2a+ years of professional Android development experience (experience with Android TV, Fire OS, or STB platforms is a major plus).
  • Strong proficiency in Kotlin is required, alongside a solid understanding of Java for handling core/legacy platform components.
  • Hands-on experience with Jetpack Compose (or a strong desire to master it) and standard Android UI XML/View groups.
  • Practical experience working with GraphQL APIs (Apollo client) and handling complex data schemas.
  • Familiarity with modern architectural patterns (MVVM, MVI) and dependency injection (Hilt/Dagger).
  • Team player with strong communication skills who enjoys collaborative problem-solving.
  • Performance-oriented mindset—you care about frames-per-second, memory footprints, and network efficiency.
  • Fluent in English (written and spoken).

Our gratitude for the job done will be eternal, but we’ll also offer you:

  • Innovative technologies and platforms to “play” with.
  • Modern working environment for your comfort.
  • Friendly, ambitious, and motivated teammates to support each other.
  • Thousands of online and in-person learning opportunities to grow.
  • Challenging assignments and career development opportunities in multinational environment.
  • Attractive remuneration package.
  • Flexible working schedule and opportunity for home office.
  • Numerous additional goodies, including, but not limited to free A1 services, discounts, health insurance and services, sports center, childcare, team and family events, etc.

Not sure yet?
See us in action in our A1 Blog
.
Any questions? Contact Nadya Georgieva.
Sounds good? Apply now!
Only shortlisted candidates will be contacted.

This is a saved copy of a posting published elsewhere. Postings get taken down without notice — check the employer's site before applying. mentors.coach is not the hiring party.

Frontend Engineer

Game Mechanics Developer

Sneaky Slots

Sofiafulltime

Apply on the employer's site

Role description

Company Description

We are a bold new slot studio backed by Evolution, built to shake up the industry with fresh ideas, strong personality, and a focus on pure entertainment.
Sneaky Slots
is part of a world-class portfolio that includes some of the most successful names in iGaming, giving us the experience, reach, and technology to move fast and think big.

Our team consists of industry professionals with deep experience across leading studios, working together to create games that are loud, full of character, and instantly engaging. We believe slots should be fun first - fast-paced, visually striking, and easy to pick up, while still delivering depth and excitement for seasoned players.

Our mission is to become one of the go-to slot providers in the industry by delivering high-quality games with strong themes, modern art direction, and a clear design philosophy. We build experiences that connect with players through storytelling, gameplay flow, and transparency, making it easy to understand and enjoy every release.

Powered by Evolution’s global infrastructure and strengthened through collaboration with sister studios like
Nolimit City
, we leverage proven technology such as xMechanics to bring innovative features into our games while maintaining our own unique style.

We operate on a global scale, delivering our content to top-tier operators worldwide. With a strong release roadmap and a focus on creativity, speed, and player-first design, Sneaky Slots is here to carve out its own place in the next generation of slot entertainment.

Job Description

Do you enjoy building games? Does it excite you to understand the math behind what makes them work?

Designing games isn’t easy, especially when it comes to crafting engaging and balanced mechanics for slot games. If you’re someone who enjoys solving complex problems, thinking in probabilities, and turning ideas into working systems - we’d like to hear from you.

We’re looking for someone with a strong passion for innovative game mechanics, a solid mathematical mindset, and ideally experience with casino or slot games.

What you’ll do:

  • Design and implement slot game mechanics
  • Build and iterate on math models
  • Collaborate with a cross-functional team to deliver high-quality games
  • Analyze, test, and refine mechanics to ensure engaging and balanced gameplay
  • Continuously improve both the product and the development process

Qualifications

What we’re looking for:

  • Strong passion for games
  • Solid mathematical background
  • Proactive mindset
  • Experience in game design or development
  • Comfortable with scripting or programming (any language)

Bonus:
Experience with slot games, RNG systems, or casino products

Additional Information

What we offer:

  • Environment tailored to allow you to realize your full potential.
  • Awesome mix between all benefits of a large company and all advantages of creative startup culture.
  • Tailor-made career program and many opportunities to grow and prove yourself.
  • Company funded training.
  • Flexibility on working hours and Home Office.
  • Social Benefits – a Multisport/Coolfit card; Additional medical insurance.

This is a saved copy of a posting published elsewhere. Postings get taken down without notice — check the employer's site before applying. mentors.coach is not the hiring party.

Frontend Engineer

Senior Software Engineer - AI Code Testing & Evaluation

Mindrift

Sofiaparttime

Apply on the employer's site

Role description

Please submit your CV in English and indicate your level of English proficiency.
Mindrift connects specialists with project-based AI opportunities for leading tech companies, focused on testing, evaluating, and improving AI systems.
Participation is project-based.
What This Opportunity Involves
We're building a dataset to evaluate AI coding agents - how well a model handles real-world developer tasks.

You'll create challenging tasks and evaluation criteria within realistic simulated environments:

  • Build realistic developer environments - a virtual company with codebase, infrastructure, and context (tickets, docs, conversations) that forms a believable development history
  • Design tasks from intermediate states of these environments - craft the prompt, define what "solved" means, and ensure the task is solvable by an AI agent
  • Write tests that verify agent solutions - accept all valid approaches and reject incorrect ones, neither too strict nor too lenient
  • Iterate on tasks and tests based on QA feedback - review agent solutions, analyze failures, and refine until the evaluation is fair and robust

What This Is NOT

  • Not data labeling
  • Not prompt engineering
  • Not writing code from scratch - the agent writes most of the code; you guide and evaluate

What We Look For

  • 5+ years in software development
  • Core stack: Python (FastAPI), JavaScript/TypeScript (React), Docker, Postgres, Kafka, Redis
  • Experience writing tests (functional, integration)
  • English proficiency - B2+

Why this is hard
Frontier models are already good at coding. Creating a task that genuinely challenges the best models is non-trivial. You need to deeply understand where models fail and what scenarios reveal the difference between a good and a bad solution. Tasks have many valid solutions - writing tests that accept all correct solutions and reject incorrect ones is harder than it sounds.

How It Works
Apply → Pass qualification(s) → Join a project → Complete tasks → Get paid

Effort estimate
Tasks for this project are estimated to take 20 hours to complete, depending on complexity. This is an estimate and not a schedule requirement; you choose when and how to work. Tasks must be submitted by the deadline and meet the listed acceptance criteria to be accepted.

Compensation
Up to
$40/hr equivalent
, depending on level and pace. Tasks are estimated at :20 hours each; you set your own schedule.

This is a saved copy of a posting published elsewhere. Postings get taken down without notice — check the employer's site before applying. mentors.coach is not the hiring party.

54 more openings in this category and country

Senior Software EngineerAppfire · Bulgaria

Apply on the employer's site