Application Security Engineer

letgo, Barcelona

Buy and sell straight from your smartphone.

letgo's the largest and fastest growing app to buy and sell locally. With over 100M downloads and hundreds of millions of listings to date, letgo’s been named among the “Hottest Startups” by Wired and “Best Apps” by Google, and it’s the second fastest growing app in America since its 2015 launch. Business Insider calls letgo “the go-to app for selling your stuff” and it’s been featured by The New York Times, The Today Show, USA Today, The Verge, Fast Company, The Wall Street Journal, Fortune and hundreds of others worldwide.

Already among the most popular apps in America, letgo’s marketplace is filled with everything from electronics and cars to clothing and furniture. Listing something on letgo is as simple as taking a photo thanks to its advanced technology. It’s the only app of its kind that can automatically title and categorize an item using artificial intelligence. Plus, users can easily browse local listings, chat instantly in the app, and view each other’s profiles, ratings and reviews.

Based in our New York and Barcelona offices, our team of over 250 represents more than 30 nationalities. Fueled by our diverse expertise, letgo’s goal is to build the largest marketplace of its kind in the world. We’re looking for people who are as passionate as we are about creating something our users love and - just as importantly - who are excited by the challenge.

What responsibilities will you get when working with us?

  • Design and implement application mitigation measures in our platforms
  • Vulnerabilities assessment and tracking on our products
  • Our Products Bug Bounty Programs Management and Support
  • Identifying risk in code, applications, processes, and architecture
  • Proactively work with engineering teams to address security & compliance issues
  • Contributing feedback to engineers during all phases of the development lifecycle
  • Facilitate collaboration with other engineers, product managers, and leaders to incorporate security thinking across teams
  • Be the first response and remediation for security-related incidents and participate in on-call rotation
  • Maintaining your skills and keeping your technical knowledge current and relevant to the technologies used at letgo
  • Mentoring engineers on security best-practices and training
  • Acting as an ambassador for the security guild across teams
  • Take part in shaping the future of our security organization


  • 3+ years of relevant work experience in internet security
  • B.S. or M.S. in Computer Science or related field a plus
  • Background in software engineering and common development practices in a collaborative and dynamic environment
  • Strong technical knowledge in application security, cryptography, authentication and authorization and cloud environments
  • Deep understanding on security design architectural patterns
  • Solid background on secure coding practices with PHP, Node JS, Java and Python
  • Proven ability to ensure applications are secure throughout the software lifecycle
  • Familiarity with common tools for DAST, SAST, and IAST analysis such as Burp Suite, Checkmarx, Veracode, HP Fortify, IBM AppScan, Acunetix
  • Extensive experience in addressing web application security issues, such as those outlined in OWASP Top 10
  • Public speaking engagements or published research is also a plus
  • Excellent written and oral communication skills

letgo perks:

  • 100% covered medical, vision, and dental care premiums for you and your family
  • Competitive salary and stock options
  • Beautiful, new office in the heart of Soho and along the beach in Barcelona
  • Potential opportunities to travel to - and work in - both of our offices
  • Massage therapy (Barcelona office)
  • Fully stocked kitchens
  • Team-building activities
  • Language and other courses
  • Sports: GymForLess, yoga classes, basketball, fusbal and volleyball teams


letgo is proud to be an Equal Opportunity and Affirmative Action employer. Ensuring a diverse and inclusive workplace where we learn from each other is core to letgo's values. We do not discriminate based upon race, religion, color, national origin, gender (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender, gender identity, gender expression, transgender status, sexual stereotypes, age, status as a protected veteran, status as an individual with a disability, or other applicable legally protected characteristics.

About letgo

With over 100M downloads and 400M listings, letgo is the biggest and fastest growing app to buy and sell locally. One of America’s most popular apps, letgo’s marketplace is filled with everything from electronics, cars and collectibles to housing, clothing and furniture. With innovative features like video listings and letgo Reveal, the free app makes it easy to list what you don’t need and find great deals nearby on anything you do. Listing something is as simple as taking a photo because letgo’s technology automatically suggests a title, price and category. letgo was founded in 2015 by Alec Oxenford and Jordi Castello, with cofounder Enrique Linares joining soon after. Business Insider calls letgo “the go-to app for selling your stuff” and it’s been featured by The New York Times, The Today Show, Fast Company, The Wall Street Journal, Fortune and many others worldwide.

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Want to learn more about letgo? Visit letgo's website.