Senior Software Engineer (m/f/d)

Senior Software Engineer at Cello, an AI-powered infrastructure company. The role involves building and improving frontend widgets, backend infrastructure, and data pipelines using React, NestJS, Python, and AWS. You will work directly with stakeholders, influence architecture, and adopt AI improvements to speed up development.

• Build new features and improve existing systems.
• Influence architecture and product direction.
• Help adopt AI improvements to speed up building and shipping.
• Work directly with stakeholders.
• Touch everything from frontend widgets to backend infrastructure to data pipelines.

• Good communication skills and collaborative attitude.
• Deep backend experience with NestJS or Python (or comparable framework), and hands-on AWS knowledge from running services in production.
• Fluent in TypeScript and JavaScript.
• Infrastructure as code with Terraform or similar.
• Strong opinions about observability with OpenTelemetry, distributed tracing, structured logging, dashboards and alerting.
• Know when 'good enough' is right and when to invest in quality.
• Strong problem solver - break down complex problems and ship pragmatic solutions.
• Contribute ideas and challenge assumptions.
• Geniunely curious about the product.
• Live at the bleeding edge of agentic coding: Claude Code, Cursor, multi-agent setups, MCP servers.
• Know how code and systems actually work without AI assistant.
• Strong work ethic - take ownership, ship what you commit to.
• Familiarity with data warehousing/analytics (e.g. Snowflake, ClickHouse) - nice-to-have.
• Experience building systems at real scale: high traffic, large user base, high availability - nice-to-have.
• Solid experience with at least one frontend framework — React, Next.js, or similar - nice-to-have.