Senior Software Engineer

Position Summary

The Senior Software Engineer designs and builds the features, services, and APIs that power Onit's Contracts product line within its legal operations platform, spanning enterprise legal management, matter management, spend management, and contract lifecycle management. This engineering-focused role is built on strong Ruby on Rails expertise and sound software engineering practices: clean, tested, production-grade code, well-designed data models, and reliable, performant systems. Working with architects, product managers, designers, and fellow engineers, the Senior Software Engineer owns features end to end, sets the technical approach for their area, and mentors less experienced engineers.

Key Responsibilities

• Application Development: Design, build, and own production-grade features, services, and APIs in Ruby on Rails that deliver Contracts product capabilities from concept to production.

• Database & Data Modelling: Design relational data models and schemas and write efficient queries that keep data consistent and performant across product surfaces.

• Performance & Scalability: Profile and optimise code, queries, and services for performance, scalability, and cost as usage and data volumes grow.

• Quality & Reliability: Build automated tests, monitoring, and alerting so issues are caught early, and lead troubleshooting and root-cause analysis of production issues.

• Security & Multi-Tenancy: Implement multi-tenant data isolation, access controls, and privacy safeguards.

• Frontend Collaboration: Contribute to frontend development (e.g., React) as needed, partnering with design to deliver cohesive user experiences.

• Engineering Excellence: Set the technical approach for features in your area, lead design and code reviews, and contribute to engineering standards, CI/CD, and documentation.

• Mentoring & Collaboration: Mentor Software Engineers, and partner with product, design, and QA to deliver features from concept to production.

Required Skills

• 5+ years of professional software engineering experience building and shipping production web applications or services.

• Strong hands-on experience in Ruby on Rails (ROR), with solid software engineering fundamentals: design patterns, testing, and clean, maintainable code.

• Working knowledge of relational databases and SQL (e.g., PostgreSQL, SQL Server, or MySQL), including data modelling and writing efficient queries.

• Experience designing and building REST APIs and backend services.

• Experience writing automated tests (e.g., RSpec) and troubleshooting production issues.

• Experience with cloud platforms (AWS preferred), Git-based workflows, CI/CD, and containerisation (Docker).

• Working proficiency with AI coding tools (e.g., Claude, Cursor) to accelerate development, debugging, and test writing, with the judgment to review and validate AI-generated code before it ships.

• Clear communication and the ability to mentor engineers, explain technical trade-offs, and collaborate across product and engineering teams.

Preferred Qualifications

• Strong experience in ROR combined with strong database skills, such as advanced SQL, data modelling, and query optimisation and performance tuning on large datasets.

• Strong experience in ROR combined with frontend development experience using React.

• Candidates with strong ROR skills, average database knowledge, and frontend experience will also be considered.

• Experience with multi-tenant SaaS systems and data isolation.

• Experience building analytics, reporting, or benchmarking features in an existing transactional product.

• Background in enterprise B2B SaaS or the legal technology domain.