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Senior Backend / AI Systems Engineer

SpellbookRemote - OntarioEngineering
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Salary
Not listed
Job type
Full-time
Work mode
Remote
Posted
20 May 2026
Status
Open · checked 9d ago

About this role

Spellbook is hiring a Senior Backend / AI Systems Engineer to build robust backend infrastructure for legal AI workflows in Remote - Ontario. This hands-on position suits an experienced developer who wants to shape scalable AI systems that transactional lawyers rely on daily.

Role Overview

In this role, the engineer develops and scales backend systems that drive product capabilities like reviews, chat features, and libraries. The position involves designing low-latency inference layers and operating large-scale retrieval systems with strict data isolation. The team values pragmatic problem-solving, turning ambiguity into shipped solutions that legal professionals trust.

Key Responsibilities

Build and scale backend systems that support core product features across Spellbook.
Design low-latency, high-reliability search, inference, and orchestration layers for AI capabilities.
Build and operate RAG retrieval at scale with performance optimization and permissions-correct data isolation.
Manage core platform elements for AI, including rate limiting, retries, consistency, and safe degradation.
Partner with Product and Design teams to balance latency, accuracy, user experience, and reliability.
Utilize modern development workflows, such as agent-assisted coding, while maintaining high security and testing standards.
Participate in on-call rotations and incident response to improve overall system reliability.

Requirements

Possess 5+ years of professional experience building backend systems in production environments.
Demonstrate strong fundamentals in backend engineering, distributed systems, data modeling, concurrency, and queues.
Show strong NoSQL data modeling expertise, specifically with MongoDB schema design, indexing strategies, and query optimization.
Ability to transform ambiguous challenges into clear plans and delivered outcomes.
Exhibit strong communication skills to explain technical decisions to both technical and non-technical audiences.
Act as a pragmatic self-starter who understands scalability trade-offs and team collaboration.

Nice to Have

Experience building production LLM-powered systems, including prompt iteration, tool calling, and agent orchestration.
Experience operating high-scale vector and lexical retrieval systems.
Background in building evaluation frameworks for quality metrics and regression testing.
Familiarity with AWS CDK and operating production services inside AWS.

Skills and Tools

Node.js
TypeScript
Express
tRPC
MongoDB
Docker
AWS
AWS CDK
LLM providers like OpenAI and Anthropic

Salary and Benefits

Access to company-paid group benefits for employees and families, including funds toward mental health support.
Generous time off policies alongside holiday closures.
Monthly paid meals and an annual wellness allowance.
Parental leave top-up programs.
Competitive stock option grants as an early team member.

About the Company

Spellbook provides an AI copilot designed specifically for transactional lawyers to draft, review, and negotiate contracts directly within Microsoft Word. Over 4,000 law firms, solo practitioners, and in-house teams utilize the platform. Backed by prominent investors such as Khosla Ventures, Thomson Reuters Ventures, and Inovia Capital, the company recently raised a $50 million Series B funding round.

How to Apply

Candidates must be located in Ontario to be considered for this position. Please visit the official company careers page at spellbook.legal to apply for this job opening.

Skills and tech stack

AWSDockerNode.jsTypeScriptLLMRAG

Questions candidates ask

Where is the Senior Backend / AI Systems Engineer position located?

This role is remote based out of Ontario, and candidates must reside in Ontario to be considered.

What level of experience is required for this role?

Applicants must have 5+ years of experience building backend systems in production.

What technologies are used in the tech stack?

The tech stack includes Node.js, TypeScript, Express, tRPC, MongoDB, Docker, AWS, AWS CDK, and LLM providers like OpenAI and Anthropic.

What benefits does Spellbook offer to employees?

Benefits include company-paid group benefits with mental health support, generous time off, holiday closures, monthly paid meals, an annual wellness allowance, parental leave top-ups, and stock option grants.

How can I apply for this job?

You can apply directly on the official company careers page at spellbook.legal.

Ready to apply?

The application is on the official Spellbook careers page.

Apply on company site