Full-Stack Software Engineer

Pentasia; Greater London; Hybrid; GBP 65,000 - 80,000; Full time

Job summary

Pentasia is seeking a Full-Stack Software Engineer in Central London on a hybrid basis. You will develop and enhance web, mobile and payments platforms, review code for production readiness, and help drive secure, scalable software with AI-assisted tooling.

The role reports to the CEO with daily direction from the Lead Engineer. You will ship features across UI and data layers, implement automated tests, and collaborate on API integrations while maintaining strong security practices.

Qualifications

• 4+ years’ experience delivering web applications in a live production environment.

Responsibilities

• Ship features end to end from UI through data layer for customer-facing and internal platforms.
• Participate in dual-approval releases: peer review of Lead Engineer's code and vice versa.
• Build automated tests and maintain technical docs.
• Develop and support integrations via APIs and webhooks.
• Cover Lead Engineer's responsibilities during leave or absence.
• Work with AI-assisted development tools and validate outputs.
• Adhere to PCI DSS secure development standards.

Skills

TypeScript

React/Next.js

Node.js

SQL

PostgreSQL

Tools

Git & CI/CD

Job description

Full-Stack Software Engineer

Location: Central London (hybrid working)
Salary: £65k to £80k base, dependent on experience
Reporting line: Chief Executive Officer, with daily direction from the Lead Engineer

The opportunity

My client is an FCA-regulated payments business operating across card issuing, merchant acquiring and transaction processing. Its London-based technology function is deliberately small and highly experienced, and makes heavy use of modern tooling, including AI, to achieve outsized output. The company owns and runs its full technology stack: consumer and business-facing web and mobile products, a payment gateway, and a range of internal platforms.

They are now looking for a Full-Stack Software Engineer to join this team. You will work closely with the Lead Engineer to develop and enhance the group’s web, mobile and payments platforms. You will also act as the independent reviewer for all changes going into production.

What you’ll be doing

• Shipping features and resolving issues end to end, from user interface through to the data layer, across all of the company’s customer-facing and internal platforms
• Taking part in a dual-approval process for production releases: reviewing the Lead Engineer’s code and having your own code reviewed in return
• Building automated test coverage and maintaining accurate technical documentation
• Developing and supporting integrations with third-party partners via APIs and webhooks
• Covering the Lead Engineer’s responsibilities during leave or absence
• Working with AI-assisted development tools every day, while taking full responsibility for reviewing and validating what they produce
• Applying secure development standards aligned with PCI DSS and contributing to the remediation of security weaknesses

What you’ll bring

• 4+ years’ experience delivering web applications in a live production environment
• Strong skills in TypeScript, React and/or Next.js, Node.js and SQL, ideally with PostgreSQL
• Confident use of Git, pull-request workflows and CI/CD pipelines, with a solid testing discipline
• Sound grasp of core web security principles, including the OWASP Top 10, authentication and input validation
• Hands-on use of AI coding assistants in your day-to-day work

Desirable

• Background in payments, fintech or banking
• Mobile development experience with React Native or Expo
• Experience deploying to AWS or Vercel

Additional information

Applicants must hold the right to work in the UK. As the employer is a regulated financial services firm, any offer will be conditional on satisfactory references and a criminal background check. My client is committed to equal opportunities.