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 is seeking a Senior Full Stack Engineer to develop secure APIs that integrate IAM solutions with core applications. The role offers the chance to work in a cutting-edge, AI-driven environment while applying Zero Trust principles. Candidates should have significant experience in TypeScript, C#, and AWS, as well as a strong understanding of security protocols and secure coding practices. This permanent position allows for 95% remote work and comes with a competitive salary of £85k-£90k plus bonus and benefits.

Benefits

Bonus

Benefits

95% remote work

Qualifications

• Strong full-stack development skills in TypeScript, C#, AWS.
• In-depth understanding of Zero Trust & OAuth2 security frameworks.
• Experience with OIDC-compliant identity providers.

Responsibilities

• Build full-stack APIs and integrations in TypeScript, C#, AWS IAM.
• Deliver secure login and SSO services using AWS.
• Collaborate with teams to embed identity into new features.

Skills

Full-stack development

AWS expertise

Security mindset

RESTful APIs

Mentoring and collaboration

Tools

TypeScript

C#

AWS IAM

Auth0

Okta

Cognito

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