SENIOR FULLSTACK DEVELOPER (JS) - ENGLISH GOOD

As a Senior Fullstack Developer at Hola Tech., you design and lead the implementation of scalable backend services and frontend applications. You take technical ownership of one or more modules, from system design through rollout, and work on blockchain integration, microservices architecture, and high-concurrency systems. You work directly with product and design teams, mentor junior developers, and collaborate with international partners in English.

What you'll do

• Design architecture and lead the implementation of scalable backend services and frontend applications
• Own technical responsibility for one or more modules: from system design, service decomposition, and API contract definition through to rollout
• Design and implement blockchain integration workflows: smart contract integration, wallet functionality, transaction signing and submission, on-chain event handling, and off-chain state synchronisation
• Design microservices, distributed systems, and event-driven architectures; solve high-concurrency and large-scale transaction problems
• Optimise performance, scalability, and reliability; establish monitoring and alerting baselines
• Review code, build coding standards, and mentor junior team members
• Work directly with product managers and designers to align scope and timeline; communicate technical details with international partners in English
• Investigate and resolve production incidents, performance bottlenecks, and complex system issues
• Make technical decisions and document them as technical design documents

What you bring

• 4+ years of full-time fullstack developer experience with strong NodeJS and NestJS skills and hands-on ReactJS experience
• Production blockchain experience: you have built or integrated smart contracts, wallets, on-chain data, or node infrastructure for real products, not just personal projects or hackathons
• Experience building and operating microservices, distributed systems, or high-concurrency platforms in production
• Hands-on experience with Docker, CI/CD, monitoring, and performance optimisation
• Good English: able to attend meetings, discuss technical details, and write documentation with international partners
• Strong understanding of clean code, SOLID principles, scalable architecture, and system design
• Proficiency with REST APIs, asynchronous processing, caching, message queues, and event-driven architecture
• Understanding of EVM and Solidity or equivalent blockchain systems
• Experience with on-chain interaction libraries such as ethers.js, web3.js, or viem
• Ability to handle gas, nonce, retry, and reorg scenarios
• Experience with PostgreSQL and Redis
• Experience with cloud platforms: GCP, AWS, Azure, or OVHcloud
• Strong knowledge of application security, authentication and authorisation, key management, and testing practices
• Proficiency with AI coding tools such as Claude or Codex in your development workflow
• Strong problem-solving skills and autonomy in Agile and Scrum environments
• Experience with mentoring or technical ownership

Nice to have

• Experience with Neo4j or other NoSQL databases

What we offer

• Salary up to 40M gross
• Five-day work week, 7.5 hours per day, 9am to 6pm with a 1.5-hour lunch break from 12pm to 1:30pm
• Full salary during probation
• Annual health check-ups
• Minimum 13 months of salary per year plus bonuses on public holidays and cultural occasions
• Performance and project bonuses
• Salary reviews twice per year
• Company events and celebrations
• Two trips per year
• Company-provided monitors and equipment; you bring your own laptop
• Professional, dynamic, and fair working environment
• Training in technical skills, soft skills, and working methods
• Career development advice and guidance
• Opportunities to advance to leadership and management positions

About Hola Tech.

Hola Tech. is a technology company building blockchain-integrated products and platforms for scale.