Senior Application Security Engineer

Stack

Responsibilities

• ▹Ensure security by design across Pennylane's application and infrastructure
• ▹Engage with the Product team to integrate security from design through delivery
• ▹Secure the main Ruby on Rails / ReactJS web application (dependencies, code, infrastructure, configuration)
• ▹Conduct code reviews from a security perspective (across roughly 80 releases per day)
• ▹Detect vulnerabilities and propose associated patches
• ▹Raise the security level of the CI/CD configuration
• ▹Secure the AWS infrastructure, including the Kubernetes (AWS EKS) environment, with the DevOps team
• ▹Conduct regular internal and external security assessments (code reviews, pentests, bug bounty)
• ▹Investigate security incidents, analyze logs, block attacks, and propose corrective measures
• ▹Ensure ISO 27001 compliance, train developers, run the Security Champions program, and raise security awareness

Requirements

• ▹Able to perform offensive security assessments on infrastructure and applications
• ▹Knowledge of exploiting and fixing a wide range of web vulnerabilities (beyond the OWASP Top 10), and explaining them to non-technical people
• ▹Experience with a programming language (Ruby, Python, JavaScript) for scripting or larger projects
• ▹Experience in cloud infrastructure security
• ▹Ability to make technical terms accessible to non-technical audiences
• ▹Fluent in French and/or English (written and spoken)

Soft skills

What we offer

• ▹25 paid vacation days, competitive compensation, company shares
• ▹Home-office setup and coworking budget
• ▹Gymlib wellness access, latest Apple equipment
• ▹Flexible remote work within Europe
• ▹Extra perks for France-based staff: RTT days, meal vouchers (Swile), Alan Blue healthcare

About the company

Pennylane is one of the fastest-growing fintechs in France. In five years it has raised a total of €359 million — including from Sequoia — added 500 new team members in 2025, and now employs over 1,000 people across 25+ nationalities; more than 1 million SMEs and 6,000 accounting firms use its service in France (4.6/5 on Glassdoor).