Senior Backend / AI Systems Engineer
Spellbook · Remote · Remote - Ontario ·
COMPENSATION
€•• – ••k
Listed on the employer's job board (Ashby)
- Senior level role
- Fully remote (Ontario)
- Node.js + TypeScript
- AI & LLM systems
- Stock options included
You will engineer the backend infrastructure powering Spellbook’s AI-driven legal tools, balancing traditional software services with modern AI workflows. The team focuses on creating robust, high-reliability systems that help lawyers draft and review contracts with precision.
This hands-on role requires turning ambiguous problems into clear technical plans while collaborating closely with product and design teams. You will own platform concerns like rate limiting and data isolation, ensuring the product remains fast and trustworthy for thousands of legal professionals.
What you'll do
- Build and scale backend systems for core features like Reviews, Chat, and Library
- Design low-latency search and orchestration layers for AI-driven functionalities
- Operate RAG retrieval at scale with optimized performance and strict data isolation
- Manage platform reliability concerns including rate limiting, retries, and fallbacks
- Collaborate with Product and Design to balance latency, accuracy, and user experience
- Utilize agent-assisted coding workflows while maintaining rigorous security standards
- Participate in on-call rotations and incident response to improve feature reliability
What you'll need
- Five or more years of experience building production backend systems
- Strong fundamentals in distributed systems, APIs, concurrency, and queues
- Expertise in NoSQL data modeling, specifically MongoDB performance tuning
- Ability to translate ambiguous high-impact problems into shipped outcomes
- Clear communication skills for explaining technical decisions to diverse audiences
- Pragmatic approach to scaling, knowing when to optimize and when to keep it simple
- Self-motivated team player eager to fix issues and improve collective workflows
Nice to have
- Experience building production LLM systems with prompt iteration and agent orchestration
- Background in operating high-scale vector and lexical search retrieval systems
- Experience creating evaluation frameworks for quality metrics and regression testing
- Proficiency with AWS CDK and managing production services on AWS infrastructure
Stack
- Node.js
- TypeScript
- Express
- tRPC
- MongoDB
- Docker
- AWS
- CDK
- OpenAI
- Anthropic
How you'll work
- Candidates must be located in Ontario
- Flexible work environment focused on outcomes
- On-call participation required as needed
What you get
- Company-paid group benefits for employees and families
- $1,000 annual allowance for mental health support
- Generous time off policies and holiday closure
- Monthly paid meals and annual wellness allowance
- Parental leave top-ups for growing families
- Competitive stock option grants for early employees