Senior Software Engineer in London

About HackerOne

HackerOne is a global leader in offensive security solutions. Our HackerOne Platform combines AI with the ingenuity of the largest community of security researchers to find and fix security, privacy, and AI vulnerabilities across the software development lifecycle. The platform offers bug bounty, vulnerability disclosure, pentesting, AI red teaming, and code security. We are trusted by industry leaders like Amazon, Anthropic, Crypto.com, General Motors, GitHub, Goldman Sachs, Uber, and the U.S. Department of Defense.

HackerOne is at a pivotal inflection point in the security industry. Offensive security is no longer optional – it is the standard for forward‑thinking companies that want to build trust and resilience in a world where AI‑driven innovation and adversaries are moving faster than ever. With the industry shifting, HackerOne stands apart: we combine the ingenuity of the largest security research community with a best‑in‑class AI‑powered platform, trusted by the world’s top organizations.

HackerOne Values

HackerOne is dedicated to fostering a strong and inclusive culture. HackerOne is Customer Obsessed and prioritises customer outcomes in our decisions and actions. We Default to Disclosure by operating with transparency and integrity, ensuring trust and accountability. Employees, researchers, customers, and partners Win Together by fostering empowerment, inclusion, respect, and accountability.

Position Summary

As a Senior Software Engineer, you will work with Product Managers and Designers to be the technical lead for a variety of challenging projects and build delightful features and products for our community and the thousands of companies that trust HackerOne with their cybersecurity posture. When you are not leading a project, you are a collaborative and effective software engineer and team member. You will interact with one of the world’s most vibrant communities of security researchers and hackers and use this experience to build delightful features and products for them and the thousands of companies who trust HackerOne with their cybersecurity posture.

As a Software Engineer, you combine broad technological expertise, deep domain knowledge, and an unquestionable dedication to business objectives as you intersect with the engineering organization. You seek leadership responsibilities, identify and spearhead new initiatives, and make systematic improvements to technical weaknesses they find in their squad’s codebases, as well as in shared codebases across the company.

At HackerOne, we embrace a Flexible Work approach, enabling our team members to work remotely while maintaining productivity and collaboration. We are seeking candidates located in London and the surrounding metropolitan areas to facilitate occasional in‑person interactions as needed. While the position is primarily remote, there will be periodic in‑person requirements to support team collaboration and foster stronger connections.

What You Will Do

Your day will start with a warm welcome online and get your tools to start! Your first 30 days will be focusing on getting to know our HackerOnies. You will join your new squad and be onboarded – get to learn the technology stack (Ruby on Rails + GraphQL + ReactJS + many more). Within 60 days, you will have committed a bunch of code to our repositories and will start developing a knack for being a fast and effective software engineer on our codebase. Within 90 days, you will start getting ready to lead your first project. You will have branched out and talked to sales, marketing, and various other functions, and you will have developed a good sense of cross‑functional collaboration and communication. Beyond 90 days, you will be a fully‑fledged software engineer. By that time you will be able to understand the business value of our products and features, and the needs of our customers, and you can translate feature requests into simple, but robust engineering (or non‑engineering) solutions.

Minimum Qualifications

• 5+ years of experience in full‑stack software engineering, especially within a SAAS environment, preferably with experience in Ruby on Rails, ReactJS and TypeScript, generative AI, ElasticSearch / OpenSearch, GraphQL
• Practical experience with GenAI and running LLM models in production
• Proven experience leading and delivering cross‑functional projects from start to finish
• Strong track record of individual contributions to business goals

Preferred Qualifications

• In‑depth understanding of LLM models

Compensation Band £90K – £110K • Offers Equity

Job Benefits

• Health (medical, vision, dental), life, and disability insurance*
• Equity stock options
• Retirement plans
• Paid public holidays and unlimited PTO
• Paid maternity and parental leave
• Leaves of absence (including caregiver leave and leave under CO’s Healthy Families and Workplaces Act)
• Employee Assistance Program
• Flexible Work Stipend

*Eligibility may differ by country

We’re committed to building a global team! For certain roles outside the United States, India, the U.K., and the Netherlands, we partner with Remote.com as our Employer of Record (EOR). Visa/work permit sponsorship is not available. Employment at HackerOne is contingent on a background check. HackerOne is an Equal Opportunity Employer in the terms and conditions of employment for all employees and job applicants without regard to race, color, religion, sex, sexual orientation, age, gender identity or gender expression, national origin, pregnancy, disability or veteran status, or any other protected characteristic as outlined by international, federal, state, or local laws. This policy applies to all HackerOne employment practices, including hiring, recruiting, promotion, termination, layoff, recall, leave of absence, compensation, benefits, training, and apprenticeship. HackerOne makes hiring decisions based solely on qualifications, merit, and business needs at the time.