Senior Python Engineer - Perm or Contract

Our 'black belt' specialists are leaders in their domains: digital champions, delivery-focused experts, top-tier security professionals, AI thought leaders, and engineering best practice advocates.

With a global footprint and deep local insight, Software at Scale delivers cutting-edge technology solutions that power mission-critical platforms. We solve complex engineering challenges at scale, driving quality, performance, and resilience through the strength of our people.

The Role & The Challenge

We are seeking an exceptional, highly proactive Senior Python Engineer who thrives in a high-trust, fully empowered environment. This is a purely hands-on execution role for a seasoned technologist who possesses deep internal knowledge of the Python ecosystem, with a specific mandate around FastAPI.

A critical focus of this role is building and optimising ultra-fast, data-intensive Software as a Service (SaaS) platforms designed to scale out horizontally. We do not micromanage. You will step into an environment where you are expected to take complete technical ownership, architect high-throughput systems, and creatively solve deep architectural puzzles.

You are not just a solo brilliant coder; you are a foundational team player. You will lead by example, establishing engineering baselines, and naturally providing the technical mentorship needed to lift the engineering capabilities of the squads around you.

Key Responsibilities

• SaaS Architecture & Scale-Out: Architect, build, and optimise multi-tenant SaaS platforms, ensuring the architecture can dynamically and horizontally scale out to handle massive concurrency.
• FastAPI Engineering: Design, build, and scale production-grade, asynchronous RESTful JSON APIs using FastAPI, ensuring optimal response times and high throughput.
• Technical Leadership & Team Uplift: Actively mentor and elevate mid-level engineers through collaborative code reviews, pair programming, and architectural whiteboard sessions.
• Data Orchestration: Build robust backend architectures that support enterprise-scale requirements, complex data orchestration, and seamless integration with front-end systems.
• DevOps & Testing: Develop and maintain frictionless CI/CD pipelines. Implement robust test automation practices (pytest), including containerised workflows using Docker.
• Cloud-Native Deployment: Leverage AWS-native services to deploy reliable, horizontally scalable Python applications.
• AI Tooling Adoption: Champion the adoption of GenAI and agentic tools where they tangibly improve engineering productivity, code quality, or system capability.
• Observability: Apply observability best practices using modern monitoring, logging, and tracing tools to proactively manage system performance and identify bottlenecks.

What You Bring

• SaaS Scaling Expertise: Mandatory commercial experience designing and engineering Software as a Service (SaaS) platforms that are explicitly built to scale out horizontally under heavy load.
• Python & FastAPI Mastery: Deep, hands-on expertise in modern Python and asynchronous programming. You must have extensive commercial experience building high-performance APIs from scratch using FastAPI.
• Proactive Execution: A proven history of hunting down answers, researching architectural trade-offs independently, and proposing fully formed solutions rather than waiting for top-down direction.
• Security & Performance: A strong track record of building secure, performant applications, optimising database queries (SQLAlchemy or similar ORMs), and implementing effective caching strategies.
• Cloud & CI/CD: Experience deploying and operating Python workloads on AWS, managing CI/CD pipelines, and working with Docker containers.
• Communication: Strong communication skills and a collaborative, execution-driven approach to solving enterprise problems.

What We Offer

• Meaningful, hands-on engineering work across complex, enterprise-grade SaaS platforms.
• Clear growth pathways from Senior to Staff and beyond.
• A low-ceremony, delivery-focused environment that values engineers who own outcomes.
• Competitive remuneration and benefits.
• The opportunity to work alongside highly experienced engineers on challenging, high-impact systems.