Senior Fullstack Developer (AI)

🚀  Senior Full Stack Developer
Xappex  ·  Full-time  ·  Remote  ·  AI-forward
 #vacancy #seniorfullstackdeveloper #вакансия
 
Xappex revolutionizes CRM data management with tools that integrate seamlessly with Excel, Excel Online, and Google Sheets. Trusted by hundreds of thousands of users globally, we're now at an inflection point — actively embedding AI across our entire product line. This is not a future roadmap item. It is happening now.
 
🛠️  What you will do
• Work across the full stack to build scalable, high-performance distributed systems that deliver excellent user experiences and drive business growth
• Develop new features and infrastructure in response to evolving product and business needs
• Lead and contribute to our AI integration initiative — designing AI-powered features including natural language interfaces, LLM-backed automation, and intelligent data handling
• Evaluate, prototype, and integrate AI APIs (including Anthropic Claude and OpenAI) into production features used by hundreds of thousands of customers
• Take ownership of projects — from concept and design all the way to deployment and iteration
• Ensure application performance, reliability, and scalability, maintaining high standards for code quality and architecture
• Contribute within an Agile environment, following best practices and continuously improving your craft
• Work primarily with JavaScript (ECMAScript 2025+), TypeScript, Node.js, React, and MySQL
• Collaborate with a distributed team across time zones using Slack, Jira, and video calls
• Actively leverage AI coding tools — including Claude Code and OpenAI Codex — to accelerate development and raise the quality bar
• Stay current with the AI landscape and bring new ideas, tools, and approaches to the team proactively
 
🎯  What you will bring
• 6+ years of experience in a similar full stack role (startup or product experience is a strong plus)
• Strong expertise in JavaScript (ECMAScript 2025+), TypeScript, Node.js, React, and MySQL
• Experience with modern UI frameworks such as Fluent UI and MobX
• Familiarity with AWS services including Lambda and DynamoDB
• Hands-on experience building AI-powered product features — integrating LLM APIs, designing prompts for production, and shipping AI to real users
• Hands-on experience with Claude Code and OpenAI Codex integrated into day-to-day engineering workflows
• Deep, genuine interest in the AI space — you follow model releases, read research, track the competitive landscape, and experiment with emerging tools
• A strong point of view on how AI is reshaping software development and SaaS products
• The ability to translate AI capabilities into concrete product value for real users
• Bachelor's degree in Computer Science, Engineering, IT, or a related field preferred
• Fluency in English and Belarusian or Russian
• A proactive, accountable problem-solving mindset
 
🤖  The AI-forward mindset we're looking for
• You know the difference between GPT-4o and Claude Sonnet — and when to use each
• You've shipped something real using an LLM API, not just tinkered in a playground
• You have hands-on opinions about prompt engineering, context windows, RAG, and agentic workflows
• You follow Anthropic, OpenAI, Google DeepMind, and the open-source ecosystem because you genuinely find it fascinating
• You are energized by AI tools, not just tolerant of them
 
🌟  Why join Xappex
• Work on products used by hundreds of thousands of customers worldwide
• Be at the center of our AI transformation — shape how AI gets built into a mature, widely-used product suite from the ground up
• Part of a lean, experienced, and collaborative team where your work has direct, visible impact
• Own projects end-to-end — build, ship, and see your work in the hands of real users fast
• We actively invest in AI tooling, research, and experimentation — you'll be encouraged to stay at the cutting edge
• Flexible, remote, friendly work environment
 
💡  At Xappex, you will have real influence over how AI shapes our products for years to come.