Senior Software Engineer

Location:

Lancing, West Sussex (Office-Based Monday-Friday)

Build Technology That Changes Lives

At TellJO, we’re using technology to help vulnerable people access support earlier, improve wellbeing, and avoid crisis.

Our SaaS platform helps organisations identify vulnerability, understand risk, and deliver better outcomes for the people they support.

We’re looking for a Senior Software Engineer to take ownership of our technology platform and play a key role in its ongoing development, operation, and security.

This is a hands‑on role with significant autonomy. You’ll be responsible for software development, cloud infrastructure, deployment pipelines, security, and operational resilience. Initially, you’ll operate as the primary technical resource, with the opportunity to help shape and grow the engineering function as the business evolves.

• Design, develop, and maintain applications using C#, .NET, React, and Type Script
• Own and improve our Azure-hosted SaaS platform
• Manage deployment pipelines and release processes using Azure Dev Ops
• Ensure the platform remains secure, reliable, scalable, and performant
• Manage Cloudflare WAF, Microsoft Defender for Cloud, and security monitoring
• Apply secure‑by‑design principles throughout the software development lifecycle
• Support ISO 27001 and Cyber Essentials compliance activities
• Troubleshoot issues across application, infrastructure, and security layers
• Contribute to product direction, technical architecture, and continuous improvement
• Use modern AI‑assisted development tools to improve productivity and code quality

• Strong understanding of OWASP Top 10 and secure software development practices
• Experience with Cloudflare WAF and web application security
• Experience with Microsoft Defender for Cloud (Azure Defender)
• Experience identifying, prioritising, and remediating security vulnerabilities
• Strong understanding of authentication, authorisation, MFA, and least‑privilege access principles
• Experience managing Azure-hosted applications and services
• Experience with Azure App Services, Azure SQL, Key Vault, Blob Storage, and monitoring tools
• Experience with Azure Dev Ops and CI/CD pipelines
• Understanding of cloud security, resilience, and operational best practices

• Strong commercial experience with C# and modern .NET
• Strong React and Type Script experience
• Experience with Entity Framework Core and SQL Server
• Experience building and maintaining REST APIs
• Experience designing scalable and maintainable software solutions
• Strong debugging, troubleshooting, and problem‑solving skills

• Comfortable operating independently and taking ownership
• Able to balance strategic thinking with hands‑on delivery
• Strong communication skills and a pragmatic approach to problem solving
• ISO 27001 or Cyber Essentials
• Experience working within regulated or security‑conscious environments

• Build technology that makes a genuine social impact
• Enjoy significant autonomy and ownership
• Work directly with senior leadership
• Influence technical decisions and platform direction
• Help shape the future engineering function as the company evolves