Full-stack Software Engineer Intern
Full Stack Software Engineer Intern - Summer 2026 (Full-time), and ASAP (Part-time)
Fastflo | Harvard Innovation Labs) · Remote
About Fastflo
Fastflo is a PE-backed B2B SaaS startup that's transforming how companies hire deskless and frontline workers. We move the entire hiring process — from application to onboarding — into candidates' native messaging apps: iMessage, WhatsApp, and SMS. No resumes, no portals, no drop-off. Candidates apply in under 2 minutes, right where they already spend their time.
We're headquartered at the Harvard Innovation Labs and integrated with 80+ applicant tracking systems. Our enterprise customers include Porsche, Volkswagen, McDonald's, and Dior. We've already turned down an acquisition offer because we believe we're just getting started.
We ship fast, and punch well above our weight. Our engineering team uses Claude Code and AI tooling as a force multiplier — you won't be fetching coffee or filing tickets.
The Role
As a Full Stack Software Engineer Intern, you'll work directly alongside our founding engineering team on production features that enterprise customers use every day. This is not a sandbox internship — you'll ship real code to real users from week one. We're looking for final year students, who can work part-time now, and convert to a Summer internship which would then turn into a full-time role. At Fastflo we keep the team tight and always promote internally before hiring externally.
You'll work across the full stack of a modern cloud-native application: building UI components, designing API endpoints, writing database queries, and integrating with third-party messaging and ATS platforms. You'll participate in architecture discussions, write tests before code, and see your work go live.
What You'll Work On
- Build and ship full-stack features across our recruiting platform
- Work with our messaging infrastructure (iMessage, WhatsApp, SMS) to create seamless candidate experiences
- Develop and maintain ATS integrations used by Fortune 500 enterprises
- Write clean, tested code following Domain-Driven Design and Layered Architecture principles
- Instrument features with analytics and monitoring
- Collaborate with the founding team on product direction — your ideas will shape the roadmap
Our Stack
Typescript · Supabase (Postgres) · Vercel · Next.js · React · AWS
What We're Looking For
- Currently pursuing a degree in Computer Science, Software Engineering, or a related field
- Hands-on experience building full-stack web applications (personal projects, coursework, or prior internships all count)
- Familiarity with modern web frameworks and JavaScript/TypeScript
- Comfort with relational databases and SQL
- Genuine curiosity about how software systems work end-to-end — from the browser to the database to the API call
- Bonus: experience with any part of our stack, exposure to AI/LLM tooling, or interest in messaging APIs and HR tech
Why Fastflo
- Real impact from day one. Small team, big clients. Your code will be used by recruiters at companies you've heard of.
- AI-native engineering culture. We use Claude Code and LLM tooling daily — you'll learn to build with AI, not just read about it.
- Founding-team access. You'll work directly with the CEO and CTO. No layers, no bureaucracy.
- PE-backed with enterprise traction. We have the resources of a funded company and the speed of a bootstrapped one.
- Harvard Innovation Labs. You'll be building out of one of the best startup ecosystems in the world.
- Strong engineering principles. Domain-Driven Design, Layered Architecture, Test-Driven Development — you'll learn patterns that will serve your entire career.
Details
Duration: Now (Part-time) & Summer 2026 (10–12 weeks)
Location: Remote, but possibility for on-site at Harvard Innovation Labs.
Compensation: Competitive stipend