Senior Software Engineer

Location: Remote

Type: Full-time

About Fastn

Fastn is on a mission to revolutionize how SaaS companies connect with their customers' environments. Powered by AI, we provide an embedded integration infrastructure that enables SaaS businesses to build, scale, and manage their integration ecosystem effortlessly.

With Fastn, companies can launch strategic integrations, create their own app marketplace, and unlock new revenue streams by offering seamless connectivity with the tools their customers already use. But our platform is more than just integrationsit’s about accelerating market penetration, driving partner-sourced revenue, and delivering smarter, more valuable customer experiences.

If you’re passionate about shaping the future of SaaS connectivity and building the next-generation app ecosystem, Fastn is the place to be.

What You’ll Do

As a Senior Software Engineer, you will play a pivotal role in architecting, developing, and scaling our AI-powered integration infrastructure. You will work closely with the founding team, product leaders, and customers to build a high-performance, ultra-scalable integration platform that processes millions of transactions per second with sub-millisecond response times. Additionally, you will lead and mentor engineering teams, driving technical excellence and innovation at scale.

Your Responsibilities

• Architect & Build: Design and develop core infrastructure, APIs, and integration workflows that power Fastn’s platform.
• Scalability & Performance: Build and optimize distributed systems that handle millions of transactions per second/minute with sub-millisecond response times.
• AI-Powered Integrations: Leverage AI-driven automation, data mapping, and smart API connectivity to enhance the integration experience.
• Security & Compliance: Implement industry-best practices for API security, data privacy, and regulatory compliance (SOC 2, GDPR, etc.).
• Technical Leadership: Lead and mentor teams, fostering a culture of high performance, innovation, and technical excellence.
• Collaboration: Work cross-functionally with product, design, and customer success teams to create a world-class developer experience.
• Strategic Impact: Influence product and technology strategy, ensuring Fastn remains at the forefront of AI-powered integration infrastructure.
  
  
  

What We’re Looking For

We’re seeking a highly skilled engineer who thrives at the intersection of SaaS, APIs, and AI. If you love solving complex challenges, building highly scalable distributed systems, and leading teams in a fast-paced, high-growth startup environment, this role is for you.

Must-Have Skills & Experience

• 5+ years of software development experience, ideally in high-performance SaaS platforms, API infrastructure, or distributed systems.
• Proven track record of building and leading engineering teams in high-growth environments.
• Strong expertise in backend development using Java, Python, or Node.js (Fastn’s stack is flexible).
• Deep knowledge of high-performance, low-latency systems with sub-millisecond response times.
• Experience designing and working with RESTful and GraphQL APIs.
• Expertise in database design & optimization (PostgreSQL, DynamoDB, or similar) for massive-scale applications.
• Experience with cloud platforms (AWS, GCP, Azure) and serverless architectures.
• Knowledge of event-driven architectures and message queues (Kafka, RabbitMQ, etc.) for handling millions of transactions per second/minute.
• Strong understanding of API security & authentication (OAuth, JWT, OpenID).
• Experience with AI/ML-driven automation in integrations is a plus.
  
  
  

Nice-to-Have Skills

• Experience with iPaaS (Integration Platform as a Service) tools like Mulesoft, Workato, or Tray.io.
• Hands-on experience with distributed systems and real-time data processing pipelines.
• Previous work in developer tooling, B2B SaaS integrations, or API marketplaces.
  
  
  

Why Join Fastn?

• Build something groundbreaking We’re redefining how SaaS companies scale their integration ecosystems.
• Work with cutting-edge AI & API technologies Be at the forefront of SaaS connectivity innovation.
• High-impact, fast-paced environment Your contributions will directly shape the success of Fastn.
• Strong engineering culture Collaborate with world-class engineers solving complex, high-scale challenges.
• Competitive compensation Market-leading salary, meaningful equity, and a flexible remote work environment.
  
  
  

Join Us in Building the Future of SaaS Connectivity!

If you’re excited to lead teams, build high-performance infrastructure, and shape the future of SaaS integrations, we’d love to hear from you.

Apply now and be part of something game-changing!