Desenvolvedor .NET Sênior — (C# / SQL Server / AppSec)

Jobgether; United States; Remote; USD 33,000 - 67,000; Full time

Benefits offered by this job

Fully remote (Brazil)

Independent contractor (PJ)

Life insurance

iFood Livre

TotalPass

Technical impact

Professional growth

Job summary

Jobgether is seeking a senior software engineer focused on secure backend development. You will craft features, refactor legacy code, and optimize performance using C# and the .NET stack, while preserving essential financial workflows.

You will strengthen API security, implement secure coding practices, and integrate SAST/DAST/SCA into CI/CD. Candidates should balance deep technical work with collaboration on security and risk reduction.

Qualifications

• Strong experience with C# and .NET including frameworks and ASP.NET Core/Web API/MVC.

Responsibilities

• Develop features, fix bugs, refactor code, and improve performance using C#/.NET.
• Maintain and modernize legacy applications while preserving business rules and critical processing workflows.
• Optimize SQL Server databases with T-SQL, stored procedures, indexes, and transactions.
• Identify, assess, and remediate vulnerabilities including insecure SQL queries and auth flaws.
• Implement secure coding to mitigate SQLi, XSS, CSRF, SSRF, and IDOR/BOLA.
• Review and strengthen API security with proper authentication/authorization.
• Conduct code reviews, regression tests, and integrate security validation into pipelines.
• Implement and maintain security tools: SAST/DAST/SCA.
• Ensure transactional integrity, traceability, and segregation of duties for financial data.
• Apply idempotency controls and maintain logs/audit trails for compliance.
• Collaborate with teams to improve software quality and reduce risk.

Skills

C# & .NET

Web API & MVC

SQL Server & T-SQL

OWASP Top 10

OAuth 2.0 / OpenID Connect / JWT

AppSec / SAST / DAST / SCA

IIS / Windows Server

DevSecOps practices

Analytical problem solving

Tools

SAST tools

DAST tools

SCA tools

SonarQube

Snyk

IIS

Job description

Accountabilities:

- Develop new features, fix bugs, refactor existing code, and improve application performance using C#, .NET Framework, modern .NET, ASP.NET Core, Web API, and MVC.

- Maintain and modernize legacy applications while preserving existing business rules, functional behavior, and critical financial processing workflows.

- Optimize SQL Server databases by improving T-SQL queries, stored procedures, indexes, transactions, and execution performance.

- Identify, assess, and remediate application vulnerabilities, including insecure SQL queries, authentication weaknesses, authorization flaws, and risks involving sensitive data.

- Implement secure coding practices to mitigate common vulnerabilities such as SQL Injection, Cross-Site Scripting (XSS), Cross-Site Request Forgery (CSRF), Server-Side Request Forgery (SSRF), and insecure direct object references (IDOR/BOLA).

- Review and strengthen API security through appropriate authentication, authorization, access validation, and secure integration mechanisms.

- Conduct code reviews, develop regression tests, and integrate security validation into development and deployment pipelines.

- Implement and maintain application security tools and processes, including static application security testing (SAST), dynamic application security testing (DAST), and software composition analysis (SCA).

- Ensure transactional integrity, operational traceability, appropriate segregation of duties, and protection of financial positions and transactions.

- Apply idempotency controls and maintain technical evidence, logs, and audit trails to support investigations, compliance, and audit requirements.

- Collaborate with technical teams to improve software quality, strengthen security controls, and reduce operational and business risks.

Requirements:

- Strong professional experience in software development using C# and .NET, including .NET Framework, modern .NET, ASP.NET Core, Web API, and MVC.

- Advanced knowledge of Microsoft SQL Server, including T-SQL, stored procedures, transactions, indexing, query optimization, and database permissions.

- Solid understanding of secure coding principles and the OWASP Top 10, with practical experience identifying and addressing SQL Injection, XSS, CSRF, SSRF, and IDOR/BOLA vulnerabilities.

- Experience securing APIs and implementing authentication and authorization mechanisms using OAuth 2.0, OpenID Connect, JWT, and robust access validation.

- Practical knowledge of application security (AppSec), including vulnerability assessment, secure code reviews, SAST, DAST, and SCA.

- Experience maintaining and supporting legacy applications, including environments involving IIS, Windows Server, integrated authentication, and application integrations.

- Understanding of transactional integrity, access segregation, data protection, and secure processing of sensitive business information.

- Strong analytical and problem-solving skills, attention to detail, and the ability to assess technical risks without compromising critical business functionality.

- Ability to work independently, prioritize technical issues, communicate clearly, and collaborate with development and security stakeholders.

Nice to have:

- Knowledge of SOLID principles, Clean Architecture, automated testing, and API design best practices.

- Experience with DevSecOps practices, Git, CI/CD pipelines, SonarQube, Snyk, or equivalent tools.

- Familiarity with encryption, secrets management, TLS, secure logging, and audit trail implementation.

- Experience in financial services, particularly investment funds, portfolios, financial positions, transaction processing, or reconciliation workflows.

Benefits:

- Remote work: Fully remote working arrangement, offering flexibility and location independence within Brazil.

- Contract type: Independent contractor (PJ).

- Life insurance: Coverage designed to provide additional financial protection.

- iFood Livre: Access to the iFood Livre benefit program.

- TotalPass: Access to a fitness and wellness platform supporting physical activity and well-being.

- Technical impact: Opportunity to work on application security, backend engineering, database optimization, and the protection of critical business systems.

- Professional growth: Exposure to secure software development practices, vulnerability management, and modern DevSecOps approaches.