Software Engineer - ML (Toronto)

Build something great. Accelerate your career.

Job Description

Reffie is an early-stage startup building the next-generation workflow and data analytics platform for residential real estate owners, operators, and property managers.

Antiquated software causes renting to be a painful experience for everyone involved. Our mission is to streamline rental communications and house families faster.

As one of our first five engineering hires beyond the founding team, you will influence key technical decisions and architect features that have a direct impact on hundreds of thousands of renters.

We are looking for highly driven and creative engineers who enjoy collaborating and working in person with other talented engineers. We are strongly biased towards people with previous start-up experience. You should thrive on shared problem-solving, fast feedback loops, and the kind of technical and creative momentum that only happens when smart people are in a room together.

Why Work for Us?

  • We are a small and passionate team with an expanding Toronto presence. We work in-office several days a week in Toronto. High-bandwidth collaboration and team cohesion matter to us—this is not a remote role.

  • We are backed by top early-stage VCs including Haystack, Trust, and Redbud. 

  • You’ll ship real features, own entire systems, and work across the stack if you choose to.

  • You want to enter on the ground floor of a fast-growing startup, learn a ton, and accelerate your career trajectory.

What You'll Do

  • Work with pre-trained LLMs (e.g. OpenAI, Claude, open-weight models) to power Reffie’s workflows. This includes prompt engineering, evaluating model performance, and fine-tuning where appropriate. You will monitor the performance, scalability, and reliability of those models after deployment.

  • Design scalable, production-grade ML integrations that help renters and leasing agents communicate more effectively.

  • Stay on top of the foundation model and applied ML landscape: new models, techniques, and tooling. Help us identify what is pragmatic to adopt.

  • Collaborate with team members on the full SDLC: design and architecture, sprint planning, development and issue tracking, code reviews, and testing and monitoring.

  • Write clean, testable, maintainable, Python code.

About You

Required

  • BS/MS in Computer Science or related field. Some AI/ML coursework required.

  • 3+ years of experience in software development

  • Strong Python skills and comfort with the data science stack: Python, jupyter, sklearn, pandas, numpy, etc. 

  • You are well-versed with at least one machine learning framework (tensorflow, pytorch, keras, etc).

  • You have integrated pre-trained models (especially LLMs) into production systems and know how to evaluate and monitor their performance, reliability, and cost.

  • Willing and excited to work in-person with the rest of the team in our Toronto office.

Be prepared to answer technical interview questions and code in all required languages and technologies.

Nice to Have

  • Experience with FastAPI and async Python.

  • Familiarity with MLFlow or similar MLOps tools.

  • Exposure to deploying cloud infrastructure with Terraform or a similar tool, AWS, and Docker.

Consider applying even if you don’t meet all the nice-to-haves. Our ideal candidate is, most importantly, a fast learner.

Hiring Process

screening call → technical interview → take-home test (est. 3hrs) → review & culture fit

Tech Stack

  • Backend is written in Python with a mix of k8s microservices (EKS) and AWS Lambdas. Our infrastructure is hosted on AWS and our DBMS is Postgres.

  • Terraform is used for infrastructure provisioning. Grafana for monitoring.

  • Frontend is a statically built React app written in TypeScript and served using S3 + CloudFront.

Our philosophy in choosing technology is: debugging problems is hard enough without finding problems in core infrastructure. Simple is better.

To Apply

Send an email with your resume to careers [at] reffie [dot] me. Resumes must:

  • Include a link to your LinkedIn profile.

  • Include a link to your GitHub profile.

  • Be in PDF format.

  • Have max 2 pages.

Your resume should also highlight your level of competence with the required skills where relevant. In the body of the email, please include a link to your favourite XKCD comic to indicate you read the instructions all the way to the end.

Please note: We will only be accepting applicants who are located in the Toronto area. Work authorization in Canada is required.