Mid Java Developer
Zielona Góra, Poland
Full time
Office
Compensation is not specified
Role
Backend Engineer
Description
About us:
B2C2 is a pioneering digital asset company shaping the future ecosystem.
The company facilitates institutional access to cryptocurrencies by ensuring reliable liquidity regardless of market conditions.
Built on crypto-native technology and continuous product innovation, B2C2 is the preferred partner for diverse institutions globally. Established in 2015 and later acquired by Japanese financial group, SBI, in 2020, B2C2 operates as an independent entity. With headquarters in the UK and additional offices in the US and Japan, B2C2 OTC Ltd. holds authorization and regulation from the UK’s Financial Conduct Authority (FRN 810834).
We take pride in our company culture and our ability to attract not just top talent, but the right individuals who align with our values. If you are seeking a role in a dynamic and cutting-edge industry, please continue reading.
SCOPE OF THE ROLE
This presents an exciting opportunity for successful candidates to work within one of our Java teams.
Role and Responsibilities
- Develop and maintain efficient Java-based applications and components, ensuring high-quality code and adherence to coding standards
- Enhance and maintain in-house shared libraries to guarantee their reliability and effectiveness
- Produce robust, well-documented, thoroughly-tested, and maintainable code to meet project objectives and deadlines
- Identify and resolve software defects and technical issues promptly to minimize disruption to revenue-generating processes
- Collaborate with cross-functional teams to define and implement new features
- Participate in code reviews, incorporating feedback to enhance code quality
- Ensure good quality internal documentation is maintained and adhered to
Skills Required
- 5+ years of software development experience in Java
- Strong grasp of object-oriented programming concepts and some design patterns
- Demonstrated ability to write clean, efficient code
- Proficiency in writing automated tests and expanding test coverage for existing code
- Experience in full project lifecycle ownership, from inception to delivery
- Background in providing production support for mission-critical services
- Strong sense of ownership, autonomy, and ability to work collaboratively across all levels of an organization
- Excellent communication skills in both Polish and English at B2/C1 level
Skills Desired
- Experience with asynchronous event-driven network applications based on Netty
- Proficiency in a variety of low GC techniques in Java
- Knowledge of relational databases, SQL, and understanding of web technologies and protocols such as HTTP and Websocket
- Familiarity with technologies like PostgreSQL, Kafka, Redis, or gRPC
- Some experience with Linux, Docker, Kubernetes, and/or AWS
- Proficient in coding with Python
- Interest in the crypto industry and/or trading
Opportunity:
- Rapid personal growth with constant encouragement to deliver your best
- Exposure to cutting-edge technologies and products for enhanced productivity
- Abundant career advancement prospects within a growing organization
- Contributing to the future of finance technology, with the chance to make a meaningful impact
- Enjoy a dynamic work environment that balances hard work with fun
- Biannual performance reviews and potential for discretionary bonuses
- Empowerment to create positive changes
- Forward-thinking and vibrant corporate culture
A strong organizational culture is a key element in the success of companies, and at B2C2, we pride ourselves on being a values-driven company. Our core values include:
- Ambitious - Aspiring to make groundbreaking achievements
- Innovative - Forward-thinking in solutions for clients and employees
- Meritocratic - Recognizing and rewarding positive contributions throughout the organization
- Collegiate - Fostering teamwork in a collaborative environment
- Risk-Aware - Making informed decisions and practicing considered approaches
Equal Employment Opportunities Policy:
B2C2 is dedicated to promoting equal employment opportunities for all applicants and employees. We welcome individuals from diverse backgrounds. It is our commitment to conduct recruiting, hiring, training and rewards practices without discrimination based on race, color, religion, gender, national origin, age, disability, genetic information, marital status, or any other characteristic protected under relevant laws. Discrimination against any employee based on membership in a protected category is not tolerated at B2C2. We strive to foster an inclusive environment to attract, engage, promote, and retain top talent. Flexible working arrangements may be considered for any position.
Skills Required
B2C2
Website
www.b2c2.comCompany size
Not specified
Location
United States
Description
Not specified
Astra Byte Sync
Blockchain Specialist for Game-Fi Project
Full time
Remote
We are seeking a skilled Blockchain Specialist to become a part of our groundbreaking Game-Fi initiative! If you have a deep passion for gaming, decentralized finance, and the latest technological advancements, this could be your ideal role.
Primary Duties:
- Create and implement smart contracts for in-game transactions and assets.
- Develop secure blockchain solutions that guarantee player ownership and protect asset integrity.
- Work closely with our game development team to smoothly incorporate blockchain technology into our gaming platform.
- Keep abreast of the latest developments and best practices within the blockchain and gaming sectors.
Qualifications:
- Demonstrated experience as a Blockchain Developer or in a similar position.
- Expertise in Solidity, with experience in Ethereum or other blockchain technologies.
- Solid understanding of Game-Fi principles and how blockchain can elevate the gaming experience.
- Familiarity with DeFi protocols and tokenomics.
- Ability to work effectively within a team and convey technical information to non-technical audiences.
Desirable Skills:
- Experience in NFT development and related platforms.
- Understanding of cryptographic concepts and security best practices.
If you are eager to embrace a new challenge and contribute to the evolution of gaming through blockchain technology, we would love to hear from you!
Primary Duties:
- Create and implement smart contracts for in-game transactions and assets.
- Develop secure blockchain solutions that guarantee player ownership and protect asset integrity.
- Work closely with our game development team to smoothly incorporate blockchain technology into our gaming platform.
- Keep abreast of the latest developments and best practices within the blockchain and gaming sectors.
Qualifications:
- Demonstrated experience as a Blockchain Developer or in a similar position.
- Expertise in Solidity, with experience in Ethereum or other blockchain technologies.
- Solid understanding of Game-Fi principles and how blockchain can elevate the gaming experience.
- Familiarity with DeFi protocols and tokenomics.
- Ability to work effectively within a team and convey technical information to non-technical audiences.
Desirable Skills:
- Experience in NFT development and related platforms.
- Understanding of cryptographic concepts and security best practices.
If you are eager to embrace a new challenge and contribute to the evolution of gaming through blockchain technology, we would love to hear from you!
Payment in Crypto
Winnables
Full Stack Developer (Front End Leaning)
Full time
Remote
Job Description:
Winnables.com is looking for a creative front-end-leaning Full Stack Developer who loves bringing slick, engaging user experiences to life while still caring about the behind-the-scenes details.
You’ll collaborate closely with designers and product leads, iterate quickly on new ideas, and see the direct impact of your work in the hands of players around the world.
If you enjoy mixing imaginative front-end polish with just enough back-end know-how to make the magic happen, we’d love to hear from you.
Key Responsabilities:
Transform design mock-ups and product concepts into polished, responsive game screens, animations, and flows.
Collaborate daily with designers, product leads, and blockchain engineers to prototype, ship, and iterate on new games or new features.
Continuously test, debug, and optimize for performance across devices and network conditions.
Review code, share best practices, and help keep our small codebase clean, secure, and easy to extend.
Use player feedback and analytics to refine existing features and guide new ideas from concept to launch.
Champion accessibility and web-standards compliance, ensuring every player—regardless of device or ability—has a first-class experience.
What You’ll Be Building
Build interactive mini-games that deliver smooth, responsive gameplay.
Create real-time multiplayer features and live game mechanics.
Develop pack-opening systems with eye-catching, engaging animations.
Engineer raffle and lottery-style games that are fully on-chain and provably fair.
Implement Plinko and other physics-based games, tuned for fun and balance.
Craft user-friendly interfaces that perform flawlessly across mobile, tablet, and desktop.
Qualifications:
Tech Stack:
Core: TypeScript · React & Next.js · Node.js · Zustand · WebSockets & REST
Data & Infra: PostgreSQL (Supabase) · Redis · Docker · GitHub
Observability: Grafana · PostHog
Design & Web3: Figma · viem / wagmi
What We're Looking For
Strong experience with TypeScript and modern JavaScript
Solid understanding of React and Next.js ecosystem
Experience building real-time applications with WebSockets
Familiarity with Node.js backend development
Knowledge of PostgreSQL and database design
Experience with responsive design and mobile-first development
Understanding of state management patterns (Zustand experience preferred)
Understanding of web security fundamentals (CSRF protection, secure authentication flows, input validation)
Interest in gaming mechanics and interactive user experience.
Nice to Have
Experience with gaming or interactive application development
Knowledge of blockchain technologies and Web3 integration
Familiarity with monitoring tools (Grafana, PostHog)
Experience with Docker and containerization
Understanding of real-time multiplayer game architecture
Company Description:
Winnables.com is on a mission to re-imagine iGaming through full on-chain transparency. We believe players deserve provably fair odds, transparent math, and no black-box RNGs. Every spin and ticket purchase is recorded immutably on Ethereum, so anyone can audit the outcome, track prize pools, or even build their own analytics on top of our contracts.
All of our games are designed and engineered 100% in-house by a small, senior team that blends game design, cryptography, and smart-contract security. We currently operate two flagship experiences:
Raffles – transparent prize drawings where every ticket lives on-chain, letting players verify fairness before and after the draw.
Loot Packs – blockchain-powered loot boxes that reveal randomized rewards with engaging pack-opening animations.
We’re still just getting started. The roadmap is full of green-field challenges—and real, measurable impact on an industry ripe for change. Join us and help craft the next generation of fair, fun, and truly player-owned gaming.
Winnables.com is looking for a creative front-end-leaning Full Stack Developer who loves bringing slick, engaging user experiences to life while still caring about the behind-the-scenes details.
You’ll collaborate closely with designers and product leads, iterate quickly on new ideas, and see the direct impact of your work in the hands of players around the world.
If you enjoy mixing imaginative front-end polish with just enough back-end know-how to make the magic happen, we’d love to hear from you.
Key Responsabilities:
Transform design mock-ups and product concepts into polished, responsive game screens, animations, and flows.
Collaborate daily with designers, product leads, and blockchain engineers to prototype, ship, and iterate on new games or new features.
Continuously test, debug, and optimize for performance across devices and network conditions.
Review code, share best practices, and help keep our small codebase clean, secure, and easy to extend.
Use player feedback and analytics to refine existing features and guide new ideas from concept to launch.
Champion accessibility and web-standards compliance, ensuring every player—regardless of device or ability—has a first-class experience.
What You’ll Be Building
Build interactive mini-games that deliver smooth, responsive gameplay.
Create real-time multiplayer features and live game mechanics.
Develop pack-opening systems with eye-catching, engaging animations.
Engineer raffle and lottery-style games that are fully on-chain and provably fair.
Implement Plinko and other physics-based games, tuned for fun and balance.
Craft user-friendly interfaces that perform flawlessly across mobile, tablet, and desktop.
Qualifications:
Tech Stack:
Core: TypeScript · React & Next.js · Node.js · Zustand · WebSockets & REST
Data & Infra: PostgreSQL (Supabase) · Redis · Docker · GitHub
Observability: Grafana · PostHog
Design & Web3: Figma · viem / wagmi
What We're Looking For
Strong experience with TypeScript and modern JavaScript
Solid understanding of React and Next.js ecosystem
Experience building real-time applications with WebSockets
Familiarity with Node.js backend development
Knowledge of PostgreSQL and database design
Experience with responsive design and mobile-first development
Understanding of state management patterns (Zustand experience preferred)
Understanding of web security fundamentals (CSRF protection, secure authentication flows, input validation)
Interest in gaming mechanics and interactive user experience.
Nice to Have
Experience with gaming or interactive application development
Knowledge of blockchain technologies and Web3 integration
Familiarity with monitoring tools (Grafana, PostHog)
Experience with Docker and containerization
Understanding of real-time multiplayer game architecture
Company Description:
Winnables.com is on a mission to re-imagine iGaming through full on-chain transparency. We believe players deserve provably fair odds, transparent math, and no black-box RNGs. Every spin and ticket purchase is recorded immutably on Ethereum, so anyone can audit the outcome, track prize pools, or even build their own analytics on top of our contracts.
All of our games are designed and engineered 100% in-house by a small, senior team that blends game design, cryptography, and smart-contract security. We currently operate two flagship experiences:
Raffles – transparent prize drawings where every ticket lives on-chain, letting players verify fairness before and after the draw.
Loot Packs – blockchain-powered loot boxes that reveal randomized rewards with engaging pack-opening animations.
We’re still just getting started. The roadmap is full of green-field challenges—and real, measurable impact on an industry ripe for change. Join us and help craft the next generation of fair, fun, and truly player-owned gaming.
Jack Milton
Full Stack Developer (Web3/Crypto)
London, UK
London, UK
Full time
Remote
We're hiring a full stack developer to help build a suite of Web3 products - lightweight tools designed to scale fast. You’ll work directly with the founding team to ship high-impact tools used by founders, investors, and crypto communities.
Over the next 4–6 months, we’re rolling out four standalone products - including a Web3 project directory, a community engagement platform, and other tools designed to drive discovery and visibility across the space. You’ll have end-to-end ownership of what you ship.
Tech Stack & Skills:
React / Next.js or similar (full stack comfort)
Node.js, Firebase, or lightweight backend setups
CMS integration (Sanity, Notion, Airtable, etc.)
REST APIs, data scraping, automation
Strong grasp of Web3 (tokens, on-chain data, dApps)
Bonus: Vercel, CoinMarketCap API, any Web3 SDKs
Who this is for:
You’ve built and shipped products solo or with small teams
You’re crypto-native and enjoy exploring new tools/protocols
You’re fast, self-driven, and prefer ownership to micromanagement
You write clean code but iterate quickly
What Success Looks Like (First 60 Days)
Launch 1–2 working products with CMS and frontend live
Build automation for token sourcing + database updates
Deliver clean UIs with fast-loading pages and working filters
Support backend tools for campaign dashboards or scraping
Details
Full-time (contractor, with option to go permanent)
Remote + async (Europe/Asia timezone preferred)
Competitive base + performance bonuses
No corporate fluff - just fast builds, useful products, and full ownership
To apply:
Send GitHub, portfolio, or 1–2 examples of tools you’ve built solo or in a small team - especially anything Web3-related.
Over the next 4–6 months, we’re rolling out four standalone products - including a Web3 project directory, a community engagement platform, and other tools designed to drive discovery and visibility across the space. You’ll have end-to-end ownership of what you ship.
Tech Stack & Skills:
React / Next.js or similar (full stack comfort)
Node.js, Firebase, or lightweight backend setups
CMS integration (Sanity, Notion, Airtable, etc.)
REST APIs, data scraping, automation
Strong grasp of Web3 (tokens, on-chain data, dApps)
Bonus: Vercel, CoinMarketCap API, any Web3 SDKs
Who this is for:
You’ve built and shipped products solo or with small teams
You’re crypto-native and enjoy exploring new tools/protocols
You’re fast, self-driven, and prefer ownership to micromanagement
You write clean code but iterate quickly
What Success Looks Like (First 60 Days)
Launch 1–2 working products with CMS and frontend live
Build automation for token sourcing + database updates
Deliver clean UIs with fast-loading pages and working filters
Support backend tools for campaign dashboards or scraping
Details
Full-time (contractor, with option to go permanent)
Remote + async (Europe/Asia timezone preferred)
Competitive base + performance bonuses
No corporate fluff - just fast builds, useful products, and full ownership
To apply:
Send GitHub, portfolio, or 1–2 examples of tools you’ve built solo or in a small team - especially anything Web3-related.
Payment in Crypto
berttha walker
UI/UX Designer
Full time
Remote
UI/UX Designer for SaaS Dashboard (Figma)
Job Summary:
We're building ClearTrack, a lightweight SaaS tool for tracking tasks and performance in remote teams. We're looking for a UI/UX designer to design 6–8 clean, modern dashboard screens (desktop + mobile).
Scope of Work:
1. Design dashboard UI (Task List, Time Tracker, Reports, Settings)
2. Create responsive mockups in Figma
3. Deliver clickable prototype + style guide
4. Collaborate with our developer for smooth handoff
Budget:
Fixed: $800–$1200 (negotiable based on experience)
Requirements:
1. SaaS/dashboard UI design experience
2. Proficiency in Figma
3. Strong communication & fast turnaround
To Apply:
If you're interested, please:
1. Send a short proposal letter explaining why you're a good fit
2. Share your portfolio (SaaS/dashboard preferred)
3. Include your email address
4. Mention your availability and estimated delivery time
Bonus if you have:
Experience designing admin panels or productivity tools
Job Summary:
We're building ClearTrack, a lightweight SaaS tool for tracking tasks and performance in remote teams. We're looking for a UI/UX designer to design 6–8 clean, modern dashboard screens (desktop + mobile).
Scope of Work:
1. Design dashboard UI (Task List, Time Tracker, Reports, Settings)
2. Create responsive mockups in Figma
3. Deliver clickable prototype + style guide
4. Collaborate with our developer for smooth handoff
Budget:
Fixed: $800–$1200 (negotiable based on experience)
Requirements:
1. SaaS/dashboard UI design experience
2. Proficiency in Figma
3. Strong communication & fast turnaround
To Apply:
If you're interested, please:
1. Send a short proposal letter explaining why you're a good fit
2. Share your portfolio (SaaS/dashboard preferred)
3. Include your email address
4. Mention your availability and estimated delivery time
Bonus if you have:
Experience designing admin panels or productivity tools
Payment in Crypto
Astra Byte Sync
Web3 Gaming Platform Development Team
Full time
Remote
Company Overview
A fastest growing Blockchain company is looking to create a decentralized gaming platform that empowers players and developers alike. We are currently seeking to build a talented team to bring their vision to life.
Position Overview
We are looking for skilled professionals to join our development team for a Web3 gaming platform. The ideal candidates will be passionate about blockchain technology and gaming, and possess the expertise to contribute to various aspects of our project. We are hiring for the following roles:
1. Frontend Developers
Responsibilities: Design and implement user interfaces for the gaming platform using modern frameworks (e.g., React, Vue.js). Collaborate with UX/UI designers to create engaging and intuitive user experiences.
Qualifications: Proficiency in HTML, CSS, JavaScript, and relevant frameworks. Experience with Web3 technologies is a plus.
2. Backend Developers
Responsibilities: Develop and maintain server-side logic, database management, and API integration. Ensure the platform's performance, security, and scalability.
Qualifications: Strong knowledge of Node.js, databases (e.g., MongoDB, PostgreSQL), and experience with cloud services. Familiarity with blockchain technology is advantageous.
3. Blockchain Developers
Responsibilities: Design and implement smart contracts, manage blockchain integrations, and ensure the security of decentralized applications. Collaborate with the team to optimize blockchain performance.
Qualifications: Expertise in Solidity, JavaScript, Rust, or Python. Experience with Ethereum and other blockchain platforms is essential.
4. Technical Leader
Responsibilities: Oversee the technical direction of the project, mentor team members, and ensure best practices in development. Collaborate with stakeholders to align technical goals with business objectives.
Qualifications: Proven experience in leading development teams, strong problem-solving skills, and a deep understanding of blockchain technologies.
5. Project Manager
Responsibilities: Manage project timelines, resources, and deliverables. Facilitate communication between team members and stakeholders, ensuring that the project stays on track and within budget.
Qualifications: Strong organizational and leadership skills, experience in project management methodologies (Agile, Scrum), and familiarity with the gaming and blockchain industries.
What We Offer
Competitive salaries and benefits
A dynamic and collaborative work environment
Opportunities for professional growth and development
The chance to be part of an innovative project that shapes the future of gaming
How to Apply
If you are passionate about gaming and blockchain technology and are excited to contribute to a groundbreaking project, we would love to hear from you! Please submit your resume and a cover letter detailing your relevant experience and why you would be a great fit for our team.
Join us in creating the next generation of gaming experiences!
A fastest growing Blockchain company is looking to create a decentralized gaming platform that empowers players and developers alike. We are currently seeking to build a talented team to bring their vision to life.
Position Overview
We are looking for skilled professionals to join our development team for a Web3 gaming platform. The ideal candidates will be passionate about blockchain technology and gaming, and possess the expertise to contribute to various aspects of our project. We are hiring for the following roles:
1. Frontend Developers
Responsibilities: Design and implement user interfaces for the gaming platform using modern frameworks (e.g., React, Vue.js). Collaborate with UX/UI designers to create engaging and intuitive user experiences.
Qualifications: Proficiency in HTML, CSS, JavaScript, and relevant frameworks. Experience with Web3 technologies is a plus.
2. Backend Developers
Responsibilities: Develop and maintain server-side logic, database management, and API integration. Ensure the platform's performance, security, and scalability.
Qualifications: Strong knowledge of Node.js, databases (e.g., MongoDB, PostgreSQL), and experience with cloud services. Familiarity with blockchain technology is advantageous.
3. Blockchain Developers
Responsibilities: Design and implement smart contracts, manage blockchain integrations, and ensure the security of decentralized applications. Collaborate with the team to optimize blockchain performance.
Qualifications: Expertise in Solidity, JavaScript, Rust, or Python. Experience with Ethereum and other blockchain platforms is essential.
4. Technical Leader
Responsibilities: Oversee the technical direction of the project, mentor team members, and ensure best practices in development. Collaborate with stakeholders to align technical goals with business objectives.
Qualifications: Proven experience in leading development teams, strong problem-solving skills, and a deep understanding of blockchain technologies.
5. Project Manager
Responsibilities: Manage project timelines, resources, and deliverables. Facilitate communication between team members and stakeholders, ensuring that the project stays on track and within budget.
Qualifications: Strong organizational and leadership skills, experience in project management methodologies (Agile, Scrum), and familiarity with the gaming and blockchain industries.
What We Offer
Competitive salaries and benefits
A dynamic and collaborative work environment
Opportunities for professional growth and development
The chance to be part of an innovative project that shapes the future of gaming
How to Apply
If you are passionate about gaming and blockchain technology and are excited to contribute to a groundbreaking project, we would love to hear from you! Please submit your resume and a cover letter detailing your relevant experience and why you would be a great fit for our team.
Join us in creating the next generation of gaming experiences!