Senior Full Stack Engineer – Typescript, C#, AWS, IAM, Security

Smart Sourcer; Remote; GBP 85,000 - 90,000; Full time

Job summary

A global B2B SaaS leader seeks a Senior Full Stack Engineer to build secure APIs and integrations in TypeScript and C#. This permanent role offers a chance to work in a cutting-edge, AI-driven environment, embracing Zero Trust security principles. Responsibilities include secure login implementations and cross-team collaborations. The ideal candidate will have strong full-stack development skills and a security-first mindset, with a salary range of £85k-£90k plus bonus and benefits, 95% remote with occasional London presence.

Benefits

Bonus

Benefits

95% remote working

Qualifications

• Strong full-stack development skills in TypeScript and C#.
• In-depth understanding of security concepts like Zero Trust and OAuth2.
• Proven experience with OIDC-compliant IDPs such as Auth0 or Okta.

Responsibilities

• Build full-stack APIs and integrations in TypeScript, C#, AWS IAM.
• Deliver secure login, SSO, MFA, RBAC / ABAC using AWS services.
• Collaborate across Product, Security, and Engineering teams.

Skills

Full-stack development skills (TypeScript, C#, AWS)

Understanding of Zero Trust & OAuth2

Experience with OIDC-compliant IDPs (Auth0, Okta, Cognito)

Solid AWS expertise (IAM, Lambda, API Gateway, CDK)

Experience in secure coding

Problem-solving and leadership skills

Job description

Senior Full Stack Engineer – Typescript, C#, AWS, IAM, Security

Outstanding opportunity to join this global B2B SaaS leader as a Senior Full Stack Engineer with some security and IAM exposure required to develop APIs to connect their IAM solution to their core applications. This permanent role offers the chance to shape how full stack applications embrace Zero Trust authentication and authorization services in a cutting-edge, AI-driven environment.

About the Role

• Build full-stack APIs and integrations in TypeScript, C#, AWS IAM
• Deliver secure login, SSO, MFA, RBAC / ABAC, and tenant isolation at scale, leveraging AWS services (Lambda, IAM, CloudFront, API Gateway, CDK)
• Collaborate across Product, Security, and Engineering teams, embed identity into new features, and uphold engineering excellence through CI / CD, testing, and incident response

Required experience

• Strong full-stack development skills (TypeScript, C#, AWS)
• An in-depth security mindset with an understanding of Zero Trust & OAuth2
• Proven experience with OIDC-compliant IDPs (Auth0, Okta, Cognito)
• Solid AWS expertise (IAM, Lambda, API Gateway, CDK)
• A proven background in building RESTful APIs that interact with IDPs
• Security-first mindset with experience in secure coding, threat modelling, and protecting PII
• Ability to mentor, collaborate, and lead with hands-on problem-solving

£85k-£90k + bonus + benefits. 95% remote & London