Blockchain Architecture & dApps
System design for dApps — node infrastructure, layer selection, cross-chain bridges, and scalable backend architecture.
Fintech, Crypto & Blockchain Architecture
We design and deliver secure, scalable architecture for fintech, crypto and blockchain projects — from smart contracts and token systems to DeFi platforms and presale infrastructure.
What We Do
From architecture design to deployment, we help crypto and fintech teams build reliable systems that scale.
System design for dApps — node infrastructure, layer selection, cross-chain bridges, and scalable backend architecture.
Secure smart contract development for Solana, Ethereum, EVM-compatible chains, Stellar, and custom blockchain environments.
Decentralized exchange logic, liquidity pools, staking mechanisms, yield strategies, and governance systems.
SPL and ERC-20/721 tokens — FoT, KYC-whitelisted, stablecoin, and RWA issuance — vesting schedules, treasury and distribution logic, and on-chain analytics.
Token and meme coin presale platforms, whitelist management, contribution tracking, and fair launch mechanisms with anti-bot protection.
Bridging traditional finance with blockchain — stablecoins, cross-border payments, payment gateways, KYC/AML flows, fiat on/off ramps, and compliant architecture.
Identity and business verification for wallets, exchanges, and fintech apps — Persona, Sumsub, Bridge.xyz, and Rain.xyz.
Learn moreOur Expertise
We combine decades of software engineering with specialized blockchain expertise. Every solution is built for security, performance, and long-term maintainability.
Solana, Ethereum, Base, BSC, Polygon, Arbitrum, Stellar
Rust, Solidity, OpenZeppelin, Anchor, Foundry
Node.js, PHP/Laravel, PostgreSQL, Redis
React, Web3.js, Ethers.js, WalletConnect, Privy
AWS, Digital Ocean, Docker, CI/CD, monitoring
Auditing, penetration testing, key management, multisig
How We Work
We analyze your requirements, tokenomics, and technical constraints to define the right architecture.
System design, smart contract specifications, and infrastructure planning before any code is written.
Iterative development with testnets, code reviews, and continuous integration throughout.
Mainnet deployment, monitoring setup, and ongoing maintenance to keep your systems running flawlessly.
About Castorweb
Castor is a specialized blockchain engineering studio. We help fintech and crypto startups build the technical foundation for their products — from the first whitepaper sketch to a live, production system.
With over 20 years of software development experience, we bring enterprise-grade engineering practices to the fast-moving fintech and crypto: clean code, thorough testing, and architectures designed to evolve.
Expert software architect with a Master of Information Technology. Passionate about building secure, scalable systems — now focused on fintech, blockchain, and decentralized technologies.
Client Testimonials
“Excellent work. Zeljko demonstrated a very high level of professionalism, quickly understood our needs, and delivered flawless execution. His assistance with the client page as well as with the setup and optimization of the billing and payment methods was particularly valuable. Communication was smooth, deadlines were respected, and the overall quality of the work was outstanding. I recommend him without reservation.”
“This is the second time working with Zeljko and an outstanding experience yet again. He managed to do a complex API integration of a payment gateway system with an existing, undocumented PHP platform. Great communication, flexibility and fast execution as always!”
“Zeljko was an absolute pleasure to work with! He exceeded my expectations by going above and beyond to meet my requirements and even took the initiative to create comprehensive documentation for the project. I would definitely work with him again!”
“Zeljko did an exceptional job with the development of a fairly complex web app that required great skills in JavaScript, React, PHP, Laravel, AWS, SQL and API integration. I have worked with dozens of developers and he is by far the most skilled in both frontend and backend development. He is always ready to respond quickly and he can get complex tasks done fast while maintaining the great quality. Definitely recommended for all web development needs.”
“Zeljko was proactive in coming up with a possible solution at an early stage, preemptively thought about possible constraints and how one could work around them above and beyond the initial job description, and was quick to iterate on the product after initial feedback and testing.”
“Zeljko has been excellent. He has top tier communication and technical skills. He comes up with innovative technical solutions to solve any problems we run into. He always adheres to deadlines. I would highly recommend him for any development work.”
“Competent and skilled developer, excellent in communication, able to resolve all issues, I will be looking to hire him again in the future!”
“Zeljko did an amazing work on my project! He was always very reactive, and could solve every problem I encountered. I'm very grateful for all what he did on my project. Thank you sooo much!!!”
“Highly competent developer, delivered on everything needed on both the back and the front end, excellent in communication and pleasant to work with. I can only recommend Zeljko and will be hiring him again!”
“Very fast, very good communication and a really good code! I recommend him 100%.”
“Understood me (another coder), delivered on time, good communication, excellent instructions, made it easy for me.”
“Zeljko completed the task successfully and on time. Our collaboration went great without any hiccups. My highest recommendations!”
“Zeljko was great to work with, very friendly and professional.”
“Really fast as always, a good problem solver! I recommend him 100%.”
“Great collaboration with Zeljko as always! My highest recommendations!”
“Great work! Very skilled — highly recommended.”
“Second experience with Zeljko, still perfect! Thanks a lot.”
“Exceptional work as always!”
“I had the pleasure of working with Zeljko for 10 years, collaborating on lots of projects. He worked as a lead programmer and is one of the most dedicated professionals I've worked with.”
Global reach
Teams we’ve worked with across five continents.
Contact
Whether you're launching a token, building a DeFi protocol, or need blockchain architecture consulting — we'd love to hear about your project.
info@castorweb.euFAQ