Senior Full Stack Developer (Agentic AI)

Reactiv

22h

About The Position

Reactiv is building the future of mobile commerce. A world where the mobile web disappears, and every shopping journey becomes instant, contextual, and native. Our platform lets brands turn any moment of intent - an ad click, QR scan, LLM search result, or real-world moment - into a fully personalized app experience with zero friction or downloads. Using Apple's App Clips, Reactiv gives marketers a new acquisition surface, a new retention channel, and a new way to build long-term customer relationships through high-intent, push-enabled experiences. Beyond Clips, Reactiv provides the full stack for next-generation commerce: deep data integration, an AI-driven marketing engine, and tools that let brands deliver richer, higher-converting experiences everywhere their customers are. We’re redefining how brands acquire, convert, and retain customers on mobile, and building the platform that powers the next decade of commerce. If you want to help shape what comes after the mobile web, we’d love to meet you. Position Overview Reactiv is seeking an experienced and innovative Senior Full Stack Developer with a focus on Agentic AI features to join our team. You’ll design, build, and deliver software solutions rapidly, working across the stack from agent architectures and data systems to integrations with mobile apps and developer workflows. You collaborate closely with product teams to deliver capabilities that solve real customer problems. You thrive in a high-ownership role on a small team, where your technical decisions directly shape the product, with an initial focus on mobile app personalization and optimization. The ideal candidate will have a strong background in large language models (LLMs) and data analysis.

Requirements

Hands-on experience building LLM-powered applications, RAG systems, or Agentic AI.
Strong Python and TypeScript proficiency with solid software engineering fundamentals.
Understanding of distributed systems, API design, and cloud-native architectures.
Experience with prompt engineering, embeddings, and vector databases.
End-to-end software development skills, including frontend development, building pipelines, tests, monitoring, and scalability.
Ability to balance engineering rigor with pragmatic delivery, embracing agentic coding tools like Cursor or Claude Code to accelerate delivery.
Clear communication skills, you surface problems early and propose solutions.
Solid understanding of data analysis and reporting, with the ability to utilize data effectively in AI-generated reports.
Experience working with large datasets and data preprocessing techniques.
Strong communication and collaboration skills, with the ability to work closely with cross-functional teams.
5+ years of production software development experience with a track record of shipping high quality solutions.
Proven track record of successfully developing and deploying AI models in a production environment.
Experience collaborating with product teams and utilizing data to drive feature development.

Nice To Haves

Experience designing, building, and deploying AI systems on modern cloud platforms such as AWS, Google Cloud, or Azure.
High degree of ownership, accountability, and initiative.
Thrives in fast-paced environments where ideas are rapidly prototyped, tested, and iterated or discarded.
Genuinely excited by autonomous AI systems and motivated by seeing your work deliver real value to customers.
Effective and adaptable collaborator across distributed, cross-functional teams.
Highly detail-oriented, with a long-term mindset focused on building systems that scale, perform, and endure.

Responsibilities

Develop and implement AI features within the Reactiv product, leveraging large language models (LLMs) and other AI technologies.
Design MCP integrations: write, maintain, and version Model Context Protocol (MCP) specs that let our in-product agents securely call internal APIs (catalog, image gen, analytics) and third-party tools.
Add Agentic UI tools directly into our drag-and-drop dashboard, putting powerful AI capabilities at customers’ fingertips.
Fine-tune prompts to enhance the performance and accuracy of AI features.
Collaborate closely with the product team to refine and enhance AI-driven features based on user feedback and business requirements.
Utilize data to generate accurate and insightful AI-generated reports, ensuring data integrity and relevance.
Analyze and process large datasets to identify trends, patterns, and insights that can inform product development.
Stay updated on the latest advancements in AI and machine learning, applying new techniques and methodologies to improve the product.
Troubleshoot and resolve issues related to AI models and features, ensuring robust and reliable performance.
Document AI development processes, model performance, optimize costs, and other relevant information for future reference and knowledge sharing.