Senior Software Developer

Location: St. Catharines

About Rentsync:
Rentsync is an award-winning, high-growth organization that provides  high quality websites, marketing services, and software solutions  to the  rental and property management industry  throughout Canada and the United States.

About the Role:

We’re building the AI products that will define the next decade of rental housing technology. We’re looking for a senior engineer who doesn’t just use AI tools, but ships production systems on top of them.

What you’ll build:

Software features and products in the rental housing / proptech landscape

Production LLM-powered features and agents

Eval harnesses, prompt versioning, and observability

Integrations via MCP and APIs

Stack you may work with:
This is a hybrid/remote position, all qualified candidates are encouraged to apply, however preferential consideration may be given to individuals who can report to one of Rentsync’s regional offices (located in Toronto, St. Catharines and Montreal) 2 days per week on average.

Duties & Responsibilities:

Design, develop, test, and maintain scalable web applications across the full stack

Write clean, maintainable, well-tested, and well-documented code following established best practices

Participate in architectural discussions and contribute to technical design decisions

Design, maintain, and optimize database schemas and queries

Develop and maintain background processing and job queues

Integrate and maintain third-party APIs and external service integrations

Implement caching strategies and performance improvements

Monitor, troubleshoot, and resolve production issues in a timely manner

Participate in code reviews to ensure code quality, security, and adherence to standards

Collaborate with product managers, designers, and stakeholders to translate business requirements into technical solutions

Contribute to sprint planning, estimation, and Agile ceremonies using Jira

Maintain application security best practices, including proper authentication, authorization, and data protection

Assist in deployment and environment configuration across cloud infrastructure, with applications containerized using Docker

Continuously evaluate and recommend improvements to systems, tooling, and development processes

Design and ship AI products

Collaboratively establish patterns others adopt; reference implementations, scaffolding, standards

Partner with product and operations

Required Knowledge, Skills & Abilities:

Strong backend development skills and comfort across modern frontend frameworks

Sound judgment on reliability, cost, latency, and security trade-offs in AI systems

You build with AI daily

Senior-level communication: you can explain a trade-off to an engineer and a stakeholder in the same meeting

Experience designing and consuming RESTful APIs (GraphQL a plus)

Strong analytical, debugging, and problem-solving skills

Effective communicator, able to collaborate across engineering, product, and design

Proficiency with Git and collaborative workflows using Git Hub

Essential

Qualifications:

6+ years building and shipping production software, with a track record of owning systems end to end

Hands-on experience putting LLMs into production; RAG, agents, tool use, structured outputs, evals

Additional

Preferred Qualifications

Workplace experience Python for ML / data work

Workplace experience with autonomous or multi-step agents in production

Background in proptech, marketplaces, or high-volume consumer platforms

Familiarity with Cloudflare's platform (Workers, Zero Trust)

Experience standing up AI observability and eval tooling

Rentsync is an equal opportunity employer. If you are selected to participate in the interview process and require unique accommodations, please don’t hesitate to let us know.

Successful candidates may be required to complete a criminal background check in the final phase of the interview process.

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