Backend Software Engineer (Junior to Mid-Level)

Remote Software Engineer (Junior to Mid-Level) ? Affiniti AI

Location: Remote (UK preferred)

Role Type: Full-time, Permanent

About Affiniti AI

Affiniti AI is building the future of AI-powered mental health support, helping therapists and patients improve engagement, therapy outcomes, and scalability of care. Our platform blends AI and evidence-based therapy techniques, offering therapists an intelligent tool to support patients between sessions. We are a mission-driven team passionate about using technology for real-world impact.

The Role

We are looking for a strong junior or mid-level software engineer who thrives in a fast-paced environment and is excited by the challenge of building and scaling AI-powered mental health tools. You will work across scalability, performance, compliance, and product development, ensuring our AI-powered therapy platform is robust, secure, and performant.

You?ll be working closely with our founders and an experienced team of engineers, product designers, and mental health professionals in an open and highly collaborative environment. Everyone contributes ideas and takes ownership of their work. This is an opportunity to be part of a fast-moving, high-impact startup where your work directly affects mental health outcomes. We move fast and expect a high level of autonomy. If you enjoy working in a high-trust environment where your decisions directly shape the product, you'll fit right in.

Key Responsibilities

Build and maintain scalable backend systems using Flask and AWS to support real-time AI-powered mental health interactions.
Ensure high availability and performance, optimizing for thousands of concurrent users while maintaining compliance with healthcare security standards.
Implement CI/CD pipelines, containerization (Docker, Kubernetes), and DevOps best practices to enable rapid deployment and high reliability.
Contribute to compliance and security efforts, ensuring secure coding practices and regulatory alignment (GDPR, UKCA, healthcare security standards).
Develop and integrate APIs with healthcare systems (FHIR, HL7, IAPTus, EMIS) (useful but not essential).
Collaborate with AI/ML teams to enhance NLP and LLM-based features (familiarity with AI tools is beneficial, but not required).
Own features from design to deployment, working closely with product and UX teams to iterate quickly and ship improvements.
Maintain a high standard of code quality, testing, and documentation.

What We?re Looking For

We value engineers who are adaptable, practical, and mission driven. If you thrive in an environment where you can take ownership, contribute ideas, and move quickly, we?d love to hear from you.

Must-Have Skills

Passionate about building technology that makes a positive real-world impact.
Comfortable iterating quickly in an agile environment where code is shipped frequently.
1-3 years experience as a backend, DevOps, or full-stack engineer.
Proficiency in Python (Flask or FastAPI).
Strong understanding of RESTful API design.
Experience with PostgreSQL (SQLAlchemy + Alembic for migrations).
Hands-on experience with OAuth2/JWT authentication.
Basic understanding of secure API design (e.g., input validation, CORS, avoiding common vulnerabilities).
Experience deploying applications on AWS (EC2, S3, Lambda).
Strong understanding of CI/CD pipelines such as GitHub Actions.
Experience with Docker.
Experience writing unit tests with pytest.

Nice-to-Have Skills

Basic understanding of MongoDB.
Knowledge of GraphQL.
Experience deploying on Kubernetes.
Familiarity with Redis.
Experience in Software as a Medical Device (SaMD) or other regulated environments.
Familiarity with LLMs, NLP models, or AI-powered applications.
Knowledge of healthcare integrations (FHIR, HL7, IAPTus, EMIS).
Frontend experience with React.js (useful but not essential).
Experience with asynchronous processing (Celery, RabbitMQ, Redis) for scalable systems.
Exposure to secure coding best practices (OWASP, HIPAA/GDPR compliance, encryption techniques).

What You Don?t Need to Have

We don?t expect you to be an expert in everything! If you?re comfortable with Python, API development, and CI/CD but haven?t worked deeply with cloud infrastructure, async processing, or AI, that?s completely fine - what matters most is your willingness to learn. We actively support skill development in these areas.

Why Join Us?

Mission-Driven Work: Your contributions will have a direct positive impact on mental health outcomes.
Remote-First: Work from anywhere, with flexibility.
Fast-Paced Startup: Ship features quickly, take ownership, and work in a high-impact environment. You?ll be trusted to make meaningful contributions from day one.
Highly Collaborative & Open Culture: We foster a supportive, transparent, and team-oriented environment where ideas are valued, and everyone has a voice. You?ll work closely with our founders, engineers, and domain experts.
Growth Opportunities: You?ll gain experience in scaling AI-powered products, healthcare compliance, and high-availability systems - ideal for engineers looking to accelerate their careers.
Clear Career Progression: As we grow, you?ll have opportunities to take on greater technical responsibility and leadership roles.

How to Apply

We keep our hiring process simple and transparent:

Initial Screening Interview (30 min) - A short conversation to learn about your background, interests, and how you approach problem-solving. We'll also share more about Affiniti AI and the role.
Take-Home Technical Task (2-4 hours) - A real-world coding challenge relevant to our work at Affiniti AI. You'll have time to complete it at your own pace within a given deadline.
Technical Deep Dive Interview (60 min) - A discussion of your solution to the task, covering trade-offs, scalability, and problem-solving approaches. We'll also explore broader technical topics such as CI/CD, DevOps, and system design.
Culture & Team Fit Interview (30-45 min) - A final chat to discuss career growth, team dynamics, and alignment with our mission.

We move fast - expect responses within days, not weeks!

Salary: £30,000-£40,000 + equity options