Software Engineer
Madrid, Spain / Portugal·Full-time·Added 3 months ago
What they offer
Full-time hours
Per the ad.
Fully remote
Per the ad.
What they ask for
Have the right to work in Spain
The Flex doesn't mention sponsorship in the ad.
Work in English
English is required, per the ad.
Have senior-level experience
Senior-level role.
This job was published 3 months ago
The role
At The Flex, we believe renting a home should feel as effortless as booking a ride.
Our mission is ambitious: enable anyone to live anywhere, anytime, without friction.
Powered by Base360.ai, our proprietary automation platform, we are building the operating system for modern renting—connecting property data, orchestrating operations, automating workflows, and enabling seamless stays across continents.
We're looking for a highly ambitious engineer who wants to build systems that create leverage at scale. This isn't a role where you'll spend months debating specifications. You'll build, ship, automate, and solve real-world problems that directly impact thousands of guests and properties.
If you're excited by APIs, automation, AI agents, cloud infrastructure, and building products from the ground up, we want to meet you.
What you'll do
Design and develop scalable applications, services, and APIs that power bookings, pricing, payments, guest experiences, and operations.
Build event-driven workflows that automate tasks previously performed by humans.
Leverage LLMs, AI agents, and machine intelligence to streamline operations, improve decision-making, and enhance customer experiences.
Create robust APIs that enable seamless communication between internal systems, third-party providers, and future products.
Build and maintain integrations with platforms including Airbnb, Hostaway, Stripe, Twilio, OpenAI, Google, and other strategic partners.
Deploy and manage cloud-native infrastructure designed for reliability, performance, and global growth.
Build solutions for:
Real-time reservation synchronization
Dynamic pricing intelligence
Smart key management
Automated guest communication
Operational forecasting
Cleaning and maintenance automation
AI-powered monitoring and alerts
Own projects end-to-end—from idea to deployment—and continuously improve the systems you build.
How you'll work
Work from anywhere. We care about outcomes, not hours.
What You'll Build
As a Founding Software Engineer, you'll help architect and scale Base360.ai—the technology platform powering every aspect of The Flex.
You'll build internal products, automation engines, AI-powered workflows, integrations, and operational systems that eliminate manual work and allow the business to scale globally.
Your work will touch everything from guest journeys and property operations to pricing intelligence and AI-driven decision-making.
Tech Stack
We care more about capability than specific technologies, but our current stack includes:
Python
FastAPI
React
TypeScript
Supabase
PostgreSQL
AWS
Serverless Architecture
OpenAI APIs
Twilio
Stripe
Docker
GitHub Actions
You Might Be a Great Fit If You Have
Strong experience building production-grade software systems
Experience with FastAPI, Python, React, or similar frameworks
Strong understanding of APIs, distributed systems, and cloud architecture
Experience designing scalable backend systems
Ability to work independently with minimal supervision
Strong problem-solving ability and product mindset
Curiosity about AI, automation, and operational efficiency
A bias toward action and shipping
Bonus points for experience with:
Property technology (PropTech)
Marketplace businesses
AI agents and workflow automation
Event-driven architectures
Supabase
AWS serverless infrastructure
What Success Looks Like
Within your first 12 months:
Core operational processes are automated through systems you've built
Manual work across the business is significantly reduced
New integrations are deployed and maintained reliably
AI-powered workflows become part of everyday operations
Base360.ai becomes a competitive advantage that enables rapid global scaling
Build Something Meaningful
Your work will directly impact how people live, travel, and experience cities around the world.
Extreme Ownership
You'll have the freedom to make decisions and build systems that matter.
Learn Faster
You'll solve real-world challenges across software, AI, automation, operations, and scale.
This Role Is Not For You If
You're looking for a slow-paced corporate environment
You prefer maintaining systems rather than building them
You need detailed instructions for every task
You avoid ownership and accountability
"Good enough" is your standard
We're not looking for someone to fill a position.
We're looking for someone to help build the future operating system of modern renting.
#LI-Remote
Pay & benefits
What you'll get
Competitive compensation with substantial upside for exceptional performers.
About The Flex
The Flex is a PropTech company operating in the real estate technology sector, focused on building software solutions for the property industry. The company is at an early stage, operating as a startup with a small, focused team. Their work centers on developing products that address challenges in the real estate market, leveraging technology to improve processes for property professionals.
The Flex has established a presence in Madrid, Spain, where they are actively hiring for their founding team. As a young startup, they offer international professionals the opportunity to join at the ground level, taking on significant ownership and responsibility in shaping the company's product and growth. Their work culture is likely dynamic and fast-paced, typical of early-stage startups, with a strong emphasis on engineering and product development.
- Industry
- PropTech
- Employees
- 50
- Headquarters
- Madrid, Spain
- In Spain
- Madrid
Good to know if you are moving
- Early-stage startup: joining now means you can have significant impact on the product and company culture.
- Based in Madrid, Spain, offering a chance to be part of a founding team in the PropTech sector.
- As a startup, the company may offer equity or other incentives to early employees, common in this stage of company growth.
- The team is small, so roles are likely to be cross-functional and offer broad responsibility.
- The company is building software for the real estate industry, a sector with global relevance.
In their own words
About the company & team
Work closely with founders and have a direct influence on product and technical direction.
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