Senior Python Developer (US Collaboration Focus) in London

We are looking for a Senior Python Developer to join our Growth and Analytics team, working closely with colleagues in both the UK and US. This role will focus on building, maintaining and evolving data-driven tools and services that support commercial growth, analytics, and marketing strategy. The successful candidate will contribute to the development of new projects while also adopting and evolving existing systems used by the US team, ensuring consistency across markets and improving scalability and performance. You will play a key role in translating business problems into technical solutions, collaborating with stakeholders across marketing, data science, editorial, and technology teams. This is a hands-on development role with opportunities to influence architecture, best practices, and the evolution of our internal tooling.

Core responsibilities

• Design, build and maintain Python-based tools and services that drive business value.
• Work closely with US-based teams, collaborating on shared projects and supporting existing tools and platforms.
• Adopt, maintain and improve existing US-developed systems.
• Develop applications and pipelines that integrate with APIs, databases, and external platforms.
• Analyse application performance and scalability, identifying opportunities for optimisation.
• Write clean, maintainable, well-tested code following team coding standards and best practices.
• Conduct code reviews and collaborate through pair programming where appropriate.
• Work with stakeholders to translate business requirements into technical solutions.
• Contribute to the architecture and design of new tools, helping ensure long-term sustainability and maintainability.
• Document systems and processes to ensure knowledge sharing across global teams.
• Support the adoption of AI in AI driven workflows.

Experience & skills required

• Strong experience developing applications in Python.
• Experience with data processing libraries such as Pandas.
• Strong understanding of SQL and relational databases (e.g., SQLAlchemy).
• Experience working with APIs and integrating multiple data sources.
• Experience with Git or similar version control systems.
• Comfortable working in Linux or MacOS environments, including Bash and cron jobs.
• Experience writing unit and integration tests.
• Ability to work with large datasets and high-volume transactional environments.
• Strong problem-solving skills and the ability to independently deliver solutions.
• Comfortable working across time zones and collaborating with international teams.

This role requires flexibility in working hours to support collaboration with the US team. Core working hours will typically be 12:00–18:00 UK time, the remaining contracted hours will vary in line with business needs, project demands and manager approval.

Desirable

• Experience building APIs using FastAPI or Flask.
• Familiarity with cloud platforms such as AWS, GCP, or Azure.
• Experience with Docker and containerised deployments.
• Experience with web scraping tools (Scrapy, Selenium, BeautifulSoup).
• Experience with data visualisation libraries such as Matplotlib or Plotly.
• Familiarity with CI/CD pipelines and DevOps practices.
• Exposure to LLM tools or frameworks (LangChain, LlamaIndex) and modern AI workflows.

Benefits

• Hybrid working model (3 days in the office).
• 28 days holiday plus bank holidays (option to buy and sell holiday days).
• Enhanced pay for maternity, paternity, adoption and shared parental leave.
• Private healthcare cover and life assurance.
• Summer Hours.
• Free access to HeadSpace, employee assistance programme (24 hour helpline), mental health first aiders, and a wellbeing portal.
• Season ticket loans (from day 1 for entry level) and cycle to work scheme.
• Relocation Rent Support Loan.
• Employee networks: HC All In (open forum), Elevate (for ethnic minority colleagues), HarperParents, Menopause at Work, Pride at HC, Social Mobility Network and Neurodiversity at Work.
• Unlimited training on our Learning and Development portal, management courses (up to MA level) and mentoring programmes.
• Virtual GP and eye care vouchers.
• Gym membership discount.
• Onsite physiotherapy (London only).
• Charitable donation matching and 2 volunteering days.
• We're a certified Carbon Neutral company.
• Free e-books and audiobooks, digital newspaper subscriptions and discounts on books.
• Subsidised canteen and retail discounts.
• Onsite prayer room.

At HarperCollins, we value authenticity and integrity in our recruitment process. To ensure a fair and accurate evaluation of all applications, we ask that all responses to assessment questions reflect your own thoughts, experiences, and capabilities. This allows us to fairly assess your knowledge, skills, and experience to determine how they align with the role. We value diverse perspectives and genuine contributions, even if answers are not perfect. The use of AI tools or external assistance to generate responses is discouraged unless explicitly permitted for specific tasks. If you wish to discuss anything regarding this position and/or your application to this role, please reach out directly to () with subject heading ‘Vacancy Query’ plus the job title and we will aim to get back to you within 5 working days. Please note, if you are interested in the role you would need to submit your application via Applied. We do not accept email applications.