Senior Software Engineer (m/f/d)

Stack

Responsibilities

• ▹Work directly with stakeholders - no walls, no ticket factory
• ▹Build new features and improve existing systems
• ▹Help decide when to ship fast to learn and when to slow down to fix the foundation
• ▹Have real influence on architecture and product direction, not just coding tickets
• ▹Help the team adopt the latest AI improvements to speed up how they build and ship

Requirements

• ▹Good communication skills and a collaborative attitude
• ▹Deep backend experience with NestJS or Python (or a comparable framework), with hands-on AWS knowledge from production
• ▹Fluent in TypeScript and JavaScript as daily drivers, not languages you've only dabbled in
• ▹Treat infrastructure as code - Terraform (or similar) is second nature, not clicking around consoles
• ▹Strong opinions on observability, backed by real work with OpenTelemetry, distributed tracing, structured logging, and alerting
• ▹Know when something is good enough, and when it's worth investing in extra quality
• ▹Strong problem-solving skills: breaking down complex, ambiguous problems and shipping pragmatic solutions
• ▹Contribute ideas and challenge assumptions, not just execute
• ▹Genuine curiosity about the product itself, wanting to understand what's being built and why
• ▹Comfortable at the bleeding edge of agentic coding (Claude Code, Cursor, multi-agent setups, MCP servers)

Soft skills

About the company

Cello is an AI-powered infrastructure company that has raised $10.3M from top-tier investors, helping SaaS companies turn their users and partners into a sales channel through referrals and sharing. Over 10 million end users interact with their system every month, and the founding team includes operators from Twilio, Wise, and Skype. The company is remote-first with regular in-person team meetups.