Senior Full Stack TypeScript

About the Role

Kaffu Salla currently recruiting on behalf of one of our merchants for a Senior Full Stack TypeScript Engineer to take ownership of an existing production system, strengthen its security, and improve its functionality without disrupting ongoing business operations.

The merchant is looking for an experienced, hands-on engineer who can understand unfamiliar and undocumented code, investigate existing system architecture, identify security vulnerabilities, and implement reliable improvements without unnecessarily rebuilding the system from scratch.

This role requires strong full-stack development skills, practical application security experience, and the ability to maintain and improve business-critical systems safely.

Key Responsibilities

1. Legacy Code Takeover and Refactoring• Take ownership of an existing production system, including code written by previous developers.

• Read, understand, and reverse-engineer undocumented code and existing system architecture.
• Identify technical risks and implement incremental improvements without unnecessary rewrites.
• Maintain system stability and business continuity while fixing bugs and improving existing functionality.

2. Full Stack Development• Develop and maintain backend services using TypeScript, Node.js, and NestJS or Express.

• Develop and maintain frontend applications using React.js or Next.js.
• Build, maintain, and integrate REST APIs.
• Work with PostgreSQL and Redis to support reliable application functionality and data management.

3. Application Security and Secrets Management• Secure API keys, credentials, environment variables, and application secrets.

• Review GitHub repositories and Git history to identify exposed secrets and leaked credentials.
• Revoke and rotate compromised API keys, credentials, and cloud access secrets.
• Apply secure coding practices and prevent common application vulnerabilities, including SQL injection.
• Implement secure authentication and server-side authorization.
• Use secure password hashing mechanisms such as bcrypt or Argon2.
• Apply appropriate encryption and access controls to protect sensitive information.

4. Sensitive Data Protection and Access Control• Protect sensitive employee information, payroll data, identity numbers, and contractual records.

• Implement granular role-based access control (RBAC).
• Enforce authorization checks on the backend to prevent users from accessing information outside their permissions.
• Identify and prevent insecure direct object reference (IDOR) vulnerabilities and unauthorized data exposure.
• Ensure that data access is properly restricted across users, roles, departments, and tenants where applicable.

5. Database Management and Safe Migrations• Design, maintain, and improve PostgreSQL databases and database schemas.

• Execute database migrations safely without breaking existing production functionality.
• Plan and implement zero-downtime migrations where required.
• Protect existing data integrity and minimize service interruptions during database changes.

6. Automated Testing and Production Reliability• Write and maintain integration tests and end-to-end (E2E) tests.

• Establish a testing safety net before refactoring existing functionality.
• Verify that changes do not introduce regression bugs.
• Troubleshoot production issues and prioritize system stability, security, and reliability.

Required Qualifications

• Strong practical experience with TypeScript and Node.js.
• Hands-on experience with NestJS or Express.
• Experience developing applications with React.js or Next.js.
• Strong knowledge of PostgreSQL and relational database design.
• Practical experience with Redis.
• Proven experience maintaining and improving existing production systems, including legacy or undocumented codebases.
• Strong understanding of application security, secure API development, and secrets management.
• Experience implementing authentication, authorization, and granular RBAC.
• Knowledge of secure password hashing, data encryption, and SQL injection prevention.
• Experience writing integration tests and end-to-end tests.
• Experience with production database migrations, with the ability to minimize downtime and prevent data loss or regressions.
• Ability to investigate unfamiliar codebases, work independently, and deliver practical solutions while maintaining business continuity.

• Strong practical experience with TypeScript and Node.js.
• Hands-on experience with NestJS or Express.
• Experience developing applications with React.js or Next.js.
• Strong knowledge of PostgreSQL and relational database design.
• Practical experience with Redis.
• Proven experience maintaining and improving existing production systems, including legacy or undocumented codebases.
• Strong understanding of application security, secure API development, and secrets management.
• Experience implementing authentication, authorization, and granular RBAC.
• Knowledge of secure password hashing, data encryption, and SQL injection prevention.
• Experience writing integration tests and end-to-end tests.
• Experience with production database migrations, with the ability to minimize downtime and prevent data loss or regressions.
• Ability to investigate unfamiliar codebases, work independently, and deliver practical solutions while maintaining business continuity.

• Accommodation: Provided by the merchant.
• Iqama Transfer Fees: Covered by the merchant.
• Medical Insurance: Provided by the merchant.