Senior Software Engineer

Who we are

At Fluxon, we believe that how you build matters as much as what you build. We help businesses navigate their most important technology decisions with confidence, and take responsibility for seeing them through. Founded by ex-Googlers and startup veterans, we’re proud to partner with teams behind some of the most ambitious products, including Google, OpenAI, Anthropic, Walmart and Stripe. 

Our work spans strategy, design, and engineering — often in complex, AI-driven environments — where clarity, speed and quality are the standard. We use AI intentionally, applying it only where it adds real value and expands what’s possible. Care shapes everything we do.

Inside Fluxon, you’ll find a global, remote-first team of experienced builders, who are curious, kind and serious about their craft. We’re building a place where people can take ownership, solve problems that matter and do work they’re proud to stand behind. If you want to do your best work alongside people who care as much as you do, you’ll feel at home here.

Note: This position is fully remote with a strong preference for a candidate based in Portugal (Lisbon). 

About the role

As a Senior Software Engineer at Fluxon, you'll have the opportunity to bring products to market while learning, contributing, and growing with our team.

You'll be responsible for:

• Driving end-to-end implementations all the way to the user, collaborating with your team to build and iterate in a dynamic environment


• Engaging directly with clients to understand business goals, give demos, and debug production issues


• Informing product requirements, identifying appropriate technical designs in partnership with our Product and Design teams


• Proactively communicating progress and challenges in your work and seeking help when you need it


• Performing code reviews and cross-feature validations


• Providing mentorship in your areas of expertise

You'll work with a diversity of technologies, including:

• Languages
  
  
  
  • TypeScript/JavaScript, Java, .Net, Python, Golang, Rust, Ruby on Rails, Kotlin, Swift
  
  
  
  


• Frameworks
  
  
  
  • Next.js, React, Angular, Spring, Expo, FastAPI, Django, SwiftUI
  
  
  
  


• Cloud Service Providers
  
  
  
  • Google Cloud Platform, Amazon Web Services, Microsoft Azure
  
  
  
  


• Cloud Services
  
  
  
  
  • Compute Engine, AWS Amplify, Fargate, Cloud Run
  
  
  • Apache Kafka, SQS, GCP CMS
  
  
  • S3, GCS
  
  
  
  


• Technologies
  
  
  
  
  • AI/ML, LLMs, Crypto, SPA, Mobile apps, Architecture redesign 
  
  
  • Google Gemini, OpenAI ChatGPT, Vertex AI, Anthropic Claude, Huggingface
  
  
  
  


• Databases
  
  
  
  • Firestore(Firebase), PostgreSQL, MariaDB, BigQuery, Supabase
  
  
  • Redis, Memcache
  
  
  
  

Qualifications

• 5+ years of industry experience in software development


• Experienced with the full product lifecycle, including CI/CD, testing, release management, deployment, monitoring and incident response


• Fluent in software design patterns, scalable system architectures, tooling, fundamentals of data structures and algorithms

What we offer

• Remote-first, flexible work with a budget to set up a work space that works for you


• Localized healthcare coverage to support you and your family’s wellbeing


• Flexible paid time off with a minimum of 3 weeks per year (plus holidays)


• "No internal meetings" Fridays, so you can focus on deep, uninterrupted work


• A professional growth budget for learning that matters to you –  whether it’s developing your technical skills or learning a new language


• A monthly wellness allowance to support your physical and mental health


• Annual company offsites, where we gather in person to build meaningful connections


• A competitive salary that reflects your expertise, impact and experience


• Profit-sharing, so you can benefit directly from the value we build together


• A paid sabbatical program, designed for rest, renewal and fresh perspective