Senior Software Engineer

The Portfolio Group; City Of London; On-site; GBP 90,000 - 130,000; Full time

Job summary

The Portfolio Group is seeking a senior software engineer for a London-based, on-site role blending backend Python and frontend TypeScript work. You will own features from design through production, building robust APIs with Python (FastAPI) and responsive UI with React.

You will tackle scalable architectures, ensure reliability, and participate in modern delivery practices, CI/CD and testing, while collaborating with senior engineers to shape the platform's evolution.

Qualifications

• Strong commercial Python experience building production services.
• Excellent TypeScript and React development experience.
• Experience with FastAPI or similar Python backend frameworks.
• Strong understanding of software architecture and system design.
• Knowledge of concurrency and asynchronous programming.

Responsibilities

• Design, develop and own end-to-end software solutions using Python and TypeScript.
• Build robust backend services and APIs with Python (FastAPI).
• Create responsive frontend apps using React and TypeScript.
• Develop and integrate services connecting AI-powered capabilities.
• Make architectural decisions around scalability, performance, reliability and maintainability.
• Write clean, tested production code and contribute to code reviews.
• Work with CI/CD pipelines and automated testing.

Skills

Python

TypeScript

React

FastAPI

AWS

CI/CD

SQL

ORMs

Architectures

Concurrency

Tools

Git

Docker

Kubernetes

PostgreSQL

Redis

CI/CD Tools

Job description

London - 5 Days On Site

50% Backend. 50% Frontend. 100% Technical Ownership.

Can you build the backend, own the frontend and confidently explain every architectural decision in between?

We're looking for a genuinely strong Senior Software Engineer who loves building complete solutions, not just working on isolated tickets.

This is a hands on, evenly balanced full-stack engineering role combining production Python development with modern TypeScript and React.

You'll be working on technically challenging products, taking ownership of features and solutions from initial design through to production, while helping shape how the wider platform evolves.

We want someone who thinks like an engineer, not just a coder. Someone who understands what happens when systems scale, when services fail, when concurrency becomes an issue and when architectural decisions have long-term consequences.

What will you be building?

• Designing, developing and owning end-to-end software solutions using Python and TypeScript.


• Building robust backend services and APIs using Python, ideally FastAPI.


• Creating responsive, maintainable frontend applications using React and TypeScript.


• Developing and integrating services that connect modern applications with AI-powered capabilities.


• Designing solutions involving APIs, databases, event-driven architectures and distributed systems.


• Working with SQL databases, ORMs and efficient data access patterns.


• Making architectural decisions around scalability, performance, reliability and maintainability.


• Writing clean, well-tested production code and contributing to code reviews.


• Working with CI/CD pipelines, automated testing and modern software delivery practices.


• Taking responsibility for solutions beyond deployment, including troubleshooting, optimisation and ongoing improvements.

What we're looking for

• We're looking for someone equally comfortable across backend and frontend engineering.


• Strong commercial Python experience building, deploying and maintaining production services.


• Excellent TypeScript and React development experience.


• Experience with FastAPI or similar Python backend frameworks.


• A strong understanding of software architecture, system design and engineering trade-offs.


• Solid knowledge of concurrency, asynchronous programming, APIs and event-driven systems.


• Experience with relational databases, SQL and ORMs.


• Confidence working with CI/CD, automated testing, Git and modern development workflows.


• Experience building scalable applications in cloud environments, ideally AWS.


• The ability to take ownership of a problem, design the solution and deliver it independently while collaborating with the wider team.


• Experience with Model Context Protocol (MCP), AI integrations or developing platforms that expose AI capabilities would be advantageous.

What really matters?

We’re not looking for someone who has simply worked alongside a Python team or occasionally contributed to a React application.

We want an engineer who has genuinely built and owned production solutions across the stack.

Someone who can explain why they chose a particular architecture, what alternatives they considered, where things went wrong and how they solved the problem.

Someone who enjoys going deep technically and takes pride in the quality of what they deliver.

Why consider this opportunity?

You’ll be joining an engineering environment where technical depth, ownership and problem-solving are genuinely valued.

You’ll have the opportunity to:

• Own meaningful projects from design to delivery.


• Work across both frontend and backend without being boxed into one discipline.


• Contribute to architectural decisions and engineering standards.


• Build software that supports innovative, AI-driven products.


• Work directly with experienced engineers and technical leaders.

If you’re a proper full-stack engineer who loves Python as much as TypeScript, enjoys complex technical challenges and wants genuine ownership, this could be exactly what you’re looking for.

INDLON

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