Senior Application Security Engineer

JR United Kingdom; Sheffield; Remote; GBP 70,000 - 90,000; Full time

Job summary

A leading company in the software supply chain industry is seeking a Senior Application Security Engineer to enhance security practices. The role involves embedding security across platforms, leading threat modeling efforts, and performing ethical penetration testing. Candidates must have strong software development backgrounds, especially in Python, and deep knowledge of application security practices.

Qualifications

• Background in software development; essential Python skills.
• Deep knowledge of application security and hands-on experience with SAST, DAST, RASP.
• Experience with securing cloud environments, particularly AWS.

Responsibilities

• Embed security across the platform from source to production.
• Lead threat modeling and conduct security reviews.
• Perform penetration testing on services and infrastructure.

Skills

Python

Application Security

Penetration Testing

Container Security

API Security

Infrastructure as Code

CI/CD Pipelines

Job description

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Senior Application Security Engineer, Sheffield, South Yorkshire

Client: Cloudsmith

Location: Sheffield, South Yorkshire, United Kingdom

Job Category: Other

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EU work permit required: Yes

Job Views: 4

Posted: 31.05.2025

Expiry Date: 15.07.2025

Job Description:

Some people like building things. Others like breaking them. You? You love both and more importantly, you love stopping bad actors from breaking the things you helped build. If that sounds like your vibe, we’ve got a job you’ll want to see.

This job is with the software supply chain company - securing and powering how software gets delivered everywhere.

What you'll do:

• Embed security across the platform, from source to production.
• Architect security controls across distributed, cloud-native systems.
• Lead threat modeling and security reviews (and get people to enjoy them).
• Perform penetration testing on services and infrastructure ethically.
• Extend security automation and monitoring with tools like CircleCI, GitHub Actions, DataDog, AWS Security Hub, etc.
• Harden everything from container runtimes to APIs to artifact pipelines.
• Write secure code, review others' code, and help everyone improve their secure coding skills.
• Build tools, automate repetitive tasks, and occasionally create a proof of concept for fun.

You need:

• A background in software development. At your core, you’re a software engineer. Python is essential, and some TypeScript is a plus.
• Deep application security knowledge.
• Hands-on experience with SAST, DAST, RASP, and securing cloud environments (preferably AWS).
• Strong understanding of container security, API security, Infrastructure as Code (IaC), and CI/CD pipelines.
• Experience with pen testing, threat modeling, and developing security tools.
• Bonus: experience securing artifact systems or supply chains.
• Bonus: familiarity with Firecracker, gVisor, or advanced security tools like SCA and data enclaves.
• You believe security should enable, not block, engineering.
• You’re diplomatic and able to work with engineering teams to secure the SDLC without causing disruption.

This job is remote within the Island of Ireland or in the UK. You must be physically located here; remote work from other countries is not permitted.

Work permit sponsorship is not available.