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
B2C2 is a leading crypto-native liquidity provider across market conditions for institutions globally.
Market Maker
Technical Cofounder – Mobile App Lead (Equity Role)
Full time
Hybrid
Looking for a Tech Cofounder (Mobile App Developer)
Equity + Leadership Role | Remote | Africa-focused
We’re building something bold — a platform designed to empower everyday people through real-world commerce and daily utility. The concept is built, the community is growing, and the brand is already in motion. Now, we’re ready to build the MVP.
We’re looking for a technical cofounder — someone with the skill to build and the vision to lead.
What You’ll Own:
• Lead the mobile app development (Android-first; iOS optional for now)
• Build core features: user registration, listings, wallet logic, escrow integration, and payments
• Collaborate on product direction and tech decisions
• Scale with the company as a core part of the founding team
Ideal Experience:
• You’ve built marketplace-style or P2P mobile apps before
• You’re comfortable with payment APIs like Paystack, Flutterwave, or others
• You understand how to work with wallets, escrow flows, and multi-user platforms
• You’re not just a builder — you want to grow with a brand and own a meaningful slice of it
Your Role Is Not Freelance.
This is a cofounder opportunity — you’ll help shape the product, tech stack, and long-term vision. You’ll receive equity and work closely with the founding team to build a scalable African-first product.
Equity + Leadership Role | Remote | Africa-focused
We’re building something bold — a platform designed to empower everyday people through real-world commerce and daily utility. The concept is built, the community is growing, and the brand is already in motion. Now, we’re ready to build the MVP.
We’re looking for a technical cofounder — someone with the skill to build and the vision to lead.
What You’ll Own:
• Lead the mobile app development (Android-first; iOS optional for now)
• Build core features: user registration, listings, wallet logic, escrow integration, and payments
• Collaborate on product direction and tech decisions
• Scale with the company as a core part of the founding team
Ideal Experience:
• You’ve built marketplace-style or P2P mobile apps before
• You’re comfortable with payment APIs like Paystack, Flutterwave, or others
• You understand how to work with wallets, escrow flows, and multi-user platforms
• You’re not just a builder — you want to grow with a brand and own a meaningful slice of it
Your Role Is Not Freelance.
This is a cofounder opportunity — you’ll help shape the product, tech stack, and long-term vision. You’ll receive equity and work closely with the founding team to build a scalable African-first product.
Iron Key Capital
Venture Fellow (Part-Time, Remote)
Part time
Remote
About Iron Key Capital:
Iron Key Capital is an investment firm specializing in liquid and venture opportunities in the crypto space. We invest in pre-seed and seed-stage Web3 startups focused on enterprise adoption of utility-driven digital assets. Additionally, we operate a blockchain innovation lab and incubate startups within the Web3 infrastructure sector. Backed by 200+ LPs globally, Iron Key deploys over $1M annually.
Role Overview:
The Venture Fellow program is an 8-week, part-time, remote opportunity designed for individuals eager to develop their skills in venture capital and angel investing. Fellows will gain hands-on experience in early-stage investing, including deal sourcing, due diligence, and pitching investment opportunities.
This program is ideal for aspiring investors, founders, or professionals exploring a career shift into venture capital. Fellows will work closely with seasoned venture capitalists and gain access to Iron Key’s investor community to learn best practices in the field.
Key Responsibilities:
Identify and evaluate early-stage investment opportunities in the Web3 ecosystem.
Conduct market research and due diligence on potential investments.
Collaborate with the Iron Key team on deal sourcing and portfolio management.
Engage with investors and team members to develop investment strategies.
Contribute to thought leadership on topics related to venture capital and Web3 innovation.
Qualifications:
Strong analytical and problem-solving skills to evaluate investment opportunities.
Excellent communication and interpersonal skills for engaging with team members and stakeholders.
Experience in Web3, AI, or related technologies is preferred.
Involvement in startups, entrepreneurial ecosystems, or Web3 communities is a plus.
Aspiring to transition into venture capital or professionalize angel investing skills.
Bonus: Previous experience as a founder or working within early-stage startups.
Program Details:
Duration: 8 weeks (part-time)
Location: Remote
Compensation: Competitive, based on experience
How to Apply:
Submit your application through this link:
https://airtable.com/appfCDlkorF5FL3VZ/pagnjuRX1A7gZjBGc/form
Additional Information:
This program is designed to take the guesswork out of breaking into venture capital or professionalizing angel investing. Successful Fellows may have opportunities to advance into Venture Partner or Core Contributor roles at Iron Key.
Iron Key Capital is an investment firm specializing in liquid and venture opportunities in the crypto space. We invest in pre-seed and seed-stage Web3 startups focused on enterprise adoption of utility-driven digital assets. Additionally, we operate a blockchain innovation lab and incubate startups within the Web3 infrastructure sector. Backed by 200+ LPs globally, Iron Key deploys over $1M annually.
Role Overview:
The Venture Fellow program is an 8-week, part-time, remote opportunity designed for individuals eager to develop their skills in venture capital and angel investing. Fellows will gain hands-on experience in early-stage investing, including deal sourcing, due diligence, and pitching investment opportunities.
This program is ideal for aspiring investors, founders, or professionals exploring a career shift into venture capital. Fellows will work closely with seasoned venture capitalists and gain access to Iron Key’s investor community to learn best practices in the field.
Key Responsibilities:
Identify and evaluate early-stage investment opportunities in the Web3 ecosystem.
Conduct market research and due diligence on potential investments.
Collaborate with the Iron Key team on deal sourcing and portfolio management.
Engage with investors and team members to develop investment strategies.
Contribute to thought leadership on topics related to venture capital and Web3 innovation.
Qualifications:
Strong analytical and problem-solving skills to evaluate investment opportunities.
Excellent communication and interpersonal skills for engaging with team members and stakeholders.
Experience in Web3, AI, or related technologies is preferred.
Involvement in startups, entrepreneurial ecosystems, or Web3 communities is a plus.
Aspiring to transition into venture capital or professionalize angel investing skills.
Bonus: Previous experience as a founder or working within early-stage startups.
Program Details:
Duration: 8 weeks (part-time)
Location: Remote
Compensation: Competitive, based on experience
How to Apply:
Submit your application through this link:
https://airtable.com/appfCDlkorF5FL3VZ/pagnjuRX1A7gZjBGc/form
Additional Information:
This program is designed to take the guesswork out of breaking into venture capital or professionalizing angel investing. Successful Fellows may have opportunities to advance into Venture Partner or Core Contributor roles at Iron Key.
Iron Key Capital
Founder Fellow
Full time
Remote
Founder Fellow
📍 Remote | 3-Month Contract
🚀 About Iron Key & Iron Key Capital
Iron Key, backed by Iron Key Capital, is a venture community and investment firm focused on liquid and venture opportunities in crypto, Web3, and AI. Our mission is to invest in and support Pre-Seed and Seed-stage startups, equipping founders and investors with the tools and knowledge they need to succeed.
We operate a blockchain innovation lab and incubate startups in venture infrastructure, fintech, IP ownership, and application development. Iron Key Capital is backed by 200+ global LPs, deploying $1M+ annually into emerging opportunities.
📢 The Opportunity: Entrepreneur in Residence (EIR)
We are seeking a technical co-founder or EIR to help bring a newly incubated venture infrastructure product to market. This is a 3-month remote contract role, ideal for builders with Web3 and AI experience who want to launch a company with hands-on support.
Iron Key has developed proprietary AI tools for internal workflows and is exploring opportunities to externalize these as software-based consulting services or standalone software products. As an EIR, you’ll play a critical role in shaping, launching, and scaling these innovations.
🔹 Key Responsibilities
Lead Startup Development – Take an incubated idea from concept to market launch.
Drive Innovation – Bring your own venture idea or work on an existing Iron Key product.
Strategic Execution – Develop and implement growth strategies.
Hands-on AI & Web3 Work – Build and iterate on cutting-edge solutions in AI and blockchain.
Leverage Resources – Work alongside investors, advisors, and a global network to accelerate your startup.
🎯 What We’re Looking For
Proven entrepreneurial experience – Ideally, you’ve built a startup before (even if it failed).
Deep Web3 or AI expertise – Hands-on experience in AI, blockchain, or fintech is a must.
Strong problem-solving mindset – Ability to pivot, adapt, and execute in fast-changing environments.
Leadership & Vision – You’re a self-starter who can drive a business forward.
🔥 Why Join Iron Key?
Founder-Centric Program – Hands-on support to launch a company.
Unmatched Network – Access to top investors, mentors, and builders in crypto and AI.
Long-Term Value – Lifetime membership in the Iron Key community & alumni network.
Fundraising Support – Get exposure to global investors and funding opportunities.
📩 Apply Now
If you're ready to build and scale a new venture, apply here:
👉 https://airtable.com/appfCDlkorF5FL3VZ/paggWhwbIDwnmlzlK/form
📍 Remote | 3-Month Contract
🚀 About Iron Key & Iron Key Capital
Iron Key, backed by Iron Key Capital, is a venture community and investment firm focused on liquid and venture opportunities in crypto, Web3, and AI. Our mission is to invest in and support Pre-Seed and Seed-stage startups, equipping founders and investors with the tools and knowledge they need to succeed.
We operate a blockchain innovation lab and incubate startups in venture infrastructure, fintech, IP ownership, and application development. Iron Key Capital is backed by 200+ global LPs, deploying $1M+ annually into emerging opportunities.
📢 The Opportunity: Entrepreneur in Residence (EIR)
We are seeking a technical co-founder or EIR to help bring a newly incubated venture infrastructure product to market. This is a 3-month remote contract role, ideal for builders with Web3 and AI experience who want to launch a company with hands-on support.
Iron Key has developed proprietary AI tools for internal workflows and is exploring opportunities to externalize these as software-based consulting services or standalone software products. As an EIR, you’ll play a critical role in shaping, launching, and scaling these innovations.
🔹 Key Responsibilities
Lead Startup Development – Take an incubated idea from concept to market launch.
Drive Innovation – Bring your own venture idea or work on an existing Iron Key product.
Strategic Execution – Develop and implement growth strategies.
Hands-on AI & Web3 Work – Build and iterate on cutting-edge solutions in AI and blockchain.
Leverage Resources – Work alongside investors, advisors, and a global network to accelerate your startup.
🎯 What We’re Looking For
Proven entrepreneurial experience – Ideally, you’ve built a startup before (even if it failed).
Deep Web3 or AI expertise – Hands-on experience in AI, blockchain, or fintech is a must.
Strong problem-solving mindset – Ability to pivot, adapt, and execute in fast-changing environments.
Leadership & Vision – You’re a self-starter who can drive a business forward.
🔥 Why Join Iron Key?
Founder-Centric Program – Hands-on support to launch a company.
Unmatched Network – Access to top investors, mentors, and builders in crypto and AI.
Long-Term Value – Lifetime membership in the Iron Key community & alumni network.
Fundraising Support – Get exposure to global investors and funding opportunities.
📩 Apply Now
If you're ready to build and scale a new venture, apply here:
👉 https://airtable.com/appfCDlkorF5FL3VZ/paggWhwbIDwnmlzlK/form
Iron Key Capital
Entrepreneur in Residence (EIR) – Crypto, Web3 & AI
Full time
Remote
Entrepreneur in Residence (EIR) – Crypto, Web3 & AI
📍 Remote | 3-Month Contract
🚀 About Iron Key & Iron Key Capital
Iron Key, backed by Iron Key Capital, is a venture community and investment firm focused on liquid and venture opportunities in crypto, Web3, and AI. Our mission is to invest in and support Pre-Seed and Seed-stage startups, equipping founders and investors with the tools and knowledge they need to succeed.
We operate a blockchain innovation lab and incubate startups in venture infrastructure, fintech, IP ownership, and application development. Iron Key Capital is backed by 200+ global LPs, deploying $1M+ annually into emerging opportunities.
📢 The Opportunity: Entrepreneur in Residence (EIR)
We are seeking a technical co-founder or EIR to help bring a newly incubated venture infrastructure product to market. This is a 3-month remote contract role, ideal for builders with Web3 and AI experience who want to launch a company with hands-on support.
Iron Key has developed proprietary AI tools for internal workflows and is exploring opportunities to externalize these as software-based consulting services or standalone software products. As an EIR, you’ll play a critical role in shaping, launching, and scaling these innovations.
🔹 Key Responsibilities
Lead Startup Development – Take an incubated idea from concept to market launch.
Drive Innovation – Bring your own venture idea or work on an existing Iron Key product.
Strategic Execution – Develop and implement growth strategies.
Hands-on AI & Web3 Work – Build and iterate on cutting-edge solutions in AI and blockchain.
Leverage Resources – Work alongside investors, advisors, and a global network to accelerate your startup.
🎯 What We’re Looking For
Proven entrepreneurial experience – Ideally, you’ve built a startup before (even if it failed).
Deep Web3 or AI expertise – Hands-on experience in AI, blockchain, or fintech is a must.
Strong problem-solving mindset – Ability to pivot, adapt, and execute in fast-changing environments.
Leadership & Vision – You’re a self-starter who can drive a business forward.
🔥 Why Join Iron Key?
Founder-Centric Program – Hands-on support to launch a company.
Unmatched Network – Access to top investors, mentors, and builders in crypto and AI.
Long-Term Value – Lifetime membership in the Iron Key community & alumni network.
Fundraising Support – Get exposure to global investors and funding opportunities.
📩 Apply Now
If you're ready to build and scale a new venture, apply here:
👉 https://airtable.com/appfCDlkorF5FL3VZ/paggWhwbIDwnmlzlK/form
📍 Remote | 3-Month Contract
🚀 About Iron Key & Iron Key Capital
Iron Key, backed by Iron Key Capital, is a venture community and investment firm focused on liquid and venture opportunities in crypto, Web3, and AI. Our mission is to invest in and support Pre-Seed and Seed-stage startups, equipping founders and investors with the tools and knowledge they need to succeed.
We operate a blockchain innovation lab and incubate startups in venture infrastructure, fintech, IP ownership, and application development. Iron Key Capital is backed by 200+ global LPs, deploying $1M+ annually into emerging opportunities.
📢 The Opportunity: Entrepreneur in Residence (EIR)
We are seeking a technical co-founder or EIR to help bring a newly incubated venture infrastructure product to market. This is a 3-month remote contract role, ideal for builders with Web3 and AI experience who want to launch a company with hands-on support.
Iron Key has developed proprietary AI tools for internal workflows and is exploring opportunities to externalize these as software-based consulting services or standalone software products. As an EIR, you’ll play a critical role in shaping, launching, and scaling these innovations.
🔹 Key Responsibilities
Lead Startup Development – Take an incubated idea from concept to market launch.
Drive Innovation – Bring your own venture idea or work on an existing Iron Key product.
Strategic Execution – Develop and implement growth strategies.
Hands-on AI & Web3 Work – Build and iterate on cutting-edge solutions in AI and blockchain.
Leverage Resources – Work alongside investors, advisors, and a global network to accelerate your startup.
🎯 What We’re Looking For
Proven entrepreneurial experience – Ideally, you’ve built a startup before (even if it failed).
Deep Web3 or AI expertise – Hands-on experience in AI, blockchain, or fintech is a must.
Strong problem-solving mindset – Ability to pivot, adapt, and execute in fast-changing environments.
Leadership & Vision – You’re a self-starter who can drive a business forward.
🔥 Why Join Iron Key?
Founder-Centric Program – Hands-on support to launch a company.
Unmatched Network – Access to top investors, mentors, and builders in crypto and AI.
Long-Term Value – Lifetime membership in the Iron Key community & alumni network.
Fundraising Support – Get exposure to global investors and funding opportunities.
📩 Apply Now
If you're ready to build and scale a new venture, apply here:
👉 https://airtable.com/appfCDlkorF5FL3VZ/paggWhwbIDwnmlzlK/form
Iron Key Capital
Entrepreneur in Residence (EIR) – Crypto, Web3 & AI
Full time
Remote
Entrepreneur in Residence (EIR) – Crypto, Web3 & AI
📍 Remote | 3-Month Contract
🚀 About Iron Key & Iron Key Capital
Iron Key, backed by Iron Key Capital, is a venture community and investment firm focused on liquid and venture opportunities in crypto, Web3, and AI. Our mission is to invest in and support Pre-Seed and Seed-stage startups, equipping founders and investors with the tools and knowledge they need to succeed.
We operate a blockchain innovation lab and incubate startups in venture infrastructure, fintech, IP ownership, and application development. Iron Key Capital is backed by 200+ global LPs, deploying $1M+ annually into emerging opportunities.
📢 The Opportunity: Entrepreneur in Residence (EIR)
We are seeking a technical co-founder or EIR to help bring a newly incubated venture infrastructure product to market. This is a 3-month remote contract role, ideal for builders with Web3 and AI experience who want to launch a company with hands-on support.
Iron Key has developed proprietary AI tools for internal workflows and is exploring opportunities to externalize these as software-based consulting services or standalone software products. As an EIR, you’ll play a critical role in shaping, launching, and scaling these innovations.
🔹 Key Responsibilities
Lead Startup Development – Take an incubated idea from concept to market launch.
Drive Innovation – Bring your own venture idea or work on an existing Iron Key product.
Strategic Execution – Develop and implement growth strategies.
Hands-on AI & Web3 Work – Build and iterate on cutting-edge solutions in AI and blockchain.
Leverage Resources – Work alongside investors, advisors, and a global network to accelerate your startup.
🎯 What We’re Looking For
Proven entrepreneurial experience – Ideally, you’ve built a startup before (even if it failed).
Deep Web3 or AI expertise – Hands-on experience in AI, blockchain, or fintech is a must.
Strong problem-solving mindset – Ability to pivot, adapt, and execute in fast-changing environments.
Leadership & Vision – You’re a self-starter who can drive a business forward.
🔥 Why Join Iron Key?
Founder-Centric Program – Hands-on support to launch a company.
Unmatched Network – Access to top investors, mentors, and builders in crypto and AI.
Long-Term Value – Lifetime membership in the Iron Key community & alumni network.
Fundraising Support – Get exposure to global investors and funding opportunities.
📩 Apply Now
If you're ready to build and scale a new venture, apply here:
👉 https://airtable.com/appfCDlkorF5FL3VZ/paggWhwbIDwnmlzlK/form
📍 Remote | 3-Month Contract
🚀 About Iron Key & Iron Key Capital
Iron Key, backed by Iron Key Capital, is a venture community and investment firm focused on liquid and venture opportunities in crypto, Web3, and AI. Our mission is to invest in and support Pre-Seed and Seed-stage startups, equipping founders and investors with the tools and knowledge they need to succeed.
We operate a blockchain innovation lab and incubate startups in venture infrastructure, fintech, IP ownership, and application development. Iron Key Capital is backed by 200+ global LPs, deploying $1M+ annually into emerging opportunities.
📢 The Opportunity: Entrepreneur in Residence (EIR)
We are seeking a technical co-founder or EIR to help bring a newly incubated venture infrastructure product to market. This is a 3-month remote contract role, ideal for builders with Web3 and AI experience who want to launch a company with hands-on support.
Iron Key has developed proprietary AI tools for internal workflows and is exploring opportunities to externalize these as software-based consulting services or standalone software products. As an EIR, you’ll play a critical role in shaping, launching, and scaling these innovations.
🔹 Key Responsibilities
Lead Startup Development – Take an incubated idea from concept to market launch.
Drive Innovation – Bring your own venture idea or work on an existing Iron Key product.
Strategic Execution – Develop and implement growth strategies.
Hands-on AI & Web3 Work – Build and iterate on cutting-edge solutions in AI and blockchain.
Leverage Resources – Work alongside investors, advisors, and a global network to accelerate your startup.
🎯 What We’re Looking For
Proven entrepreneurial experience – Ideally, you’ve built a startup before (even if it failed).
Deep Web3 or AI expertise – Hands-on experience in AI, blockchain, or fintech is a must.
Strong problem-solving mindset – Ability to pivot, adapt, and execute in fast-changing environments.
Leadership & Vision – You’re a self-starter who can drive a business forward.
🔥 Why Join Iron Key?
Founder-Centric Program – Hands-on support to launch a company.
Unmatched Network – Access to top investors, mentors, and builders in crypto and AI.
Long-Term Value – Lifetime membership in the Iron Key community & alumni network.
Fundraising Support – Get exposure to global investors and funding opportunities.
📩 Apply Now
If you're ready to build and scale a new venture, apply here:
👉 https://airtable.com/appfCDlkorF5FL3VZ/paggWhwbIDwnmlzlK/form