Platform & Security Engineer
Mast is on a mission to make complex lending simple. The UK's specialist lending market is underserved by technology, with legacy systems that can't handle the nuance of complex income, niche products, or the broker workflows that specialist lenders rely on.
We're building modern, cloud-native lending technology, purpose-built for specialist lenders, that helps them process more applications in less time, reach decisions faster, and deliver better experiences for brokers and borrowers.
We're pioneering the use of AI in mortgage origination, building it into the platform from the ground up rather than bolting it onto legacy architecture.. We work with regulated lenders across the UK, have a 100% delivery track record, and are building a high-performance team where everyone has real ownership and direct impact.
We're looking for a Platform & Security Engineer to help scale and secure the Mast platform as we continue to grow. This role combines platform engineering, cloud infrastructure, security, reliability, observability, operational resilience, and compliance. You'll work closely with the Head of Engineering to improve developer experience, modernise infrastructure, strengthen our security posture, and ensure our systems remain reliable and resilient as we onboard more clients and ship more features. This role is suited to an experienced engineer comfortable owning infrastructure, security, reliability, and operational resilience across production systems in a fast moving startup environment.
Responsibilities
Cloud & Platform
Own and maintain cloud infrastructure across AWS and container-based environments
Design, build, and maintain infrastructure using Infrastructure as Code tools such as Terraform
Support with future replatforming and infrastructure modernisation initiatives, including migration from Heroku to AWS container platforms
Security & Compliance
Manage vulnerability remediation processes including CVE tracking, security patching, and maintaining regular patching cadences
Support operational resilience (OR), disaster recovery (DR), backup strategies, and business continuity planning
Help maintain and improve security and compliance processes aligned with ISO27001 framework
System Reliability & Observability
Improve system reliability, scalability, resilience, and performance across the Mast platform
Troubleshoot infrastructure, platform, networking, and security related issues across environments
Contribute to incident response processes and ongoing operational improvements
Build systems and tooling that automate infrastructure management and operational workflows wherever possible
Implement and maintain observability tooling including monitoring, logging, alerting, and tracing
Developer Experience (DevEx)
Building tools and platforms that enable product teams to provision resources autonomously (self-service)
Building and maintaining CI/CD pipelines and deployment workflows to improve developer experience and delivery velocity
Introducing guardrails for self-service cloud engineering by development teams
Requirements
5+ years experience in either platform engineering, cloud infrastructure, SRE, DevOps, or security engineering roles
Strong experience with AWS and container based infrastructure
Experience managing infrastructure using Infrastructure as Code tools such as Terraform
Experience building and operating scalable, reliable production systems
Experience with CI/CD pipelines, deployment automation, and developer tooling
Working knowledge of Linux/Unix systems, networking, and cloud security fundamentals
Experience with observability tooling including monitoring, logging, alerting, and tracing
Experience supporting incident response, operational resilience, disaster recovery, or business continuity processes
Comfortable working across infrastructure, security, reliability, and compliance domains
Comfortable owning operational and infrastructure concerns end-to-end in a fast moving environment
Strong communication skills and ability to collaborate effectively with both technical and non-technical stakeholders
Comfortable using AI tools as part of your development workflow
Desired Attributes
Thrives in fast-paced startup environments with a strong sense of ownership and urgency
Pragmatic and solutions oriented, with strong execution skills
Strong operational mindset and calm under pressure during incidents
Self directed, highly organised, and capable of driving initiatives independently
Curious and adaptable, with a continuous improvement mindset
Focused on building practical, scalable systems that improve operational efficiency and developer experience
Experience with Ruby on Rails applications and infrastructure is highly desirable
Salary & Location
Location: London or UK Remote
Salary: £90,000 to £100,000 + Stock Options
Benefits
Stock Option Plan
25 days holiday + bank holidays
4 - 10 weeks work from anywhere, based on tenure (for UK based roles)
Vitality Health insurance
Pension plan
Equipment budget
Learning & development budget
Cycle to Work Scheme
Monthly team socials + Quarterly Team Meet-ups @ HQ
Digital-first, employee-first company with a flexible working culture + Central London HQ
Mast. is an equal opportunity employer and we celebrate diversity and are committed to creating an inclusive environment for all employees.
ABOUT US
Mast is a high-performance team of engineers and lending experts building the future of specialist lending technology. We value radical honesty, transparency, and speed. We hire exceptional people, expect a lot from each other, and offer real ownership, fast growth, and the chance to shape an industry.