[Hiring] JavaScript Engineer @Confiant

Role Description

We are seeking an experienced JavaScript Engineer to be part of the team that owns and evolves the core client-side SDK that sits at the heart of Confiant's malvertising detection and blocking technology. This is a deeply technical, specialized role focused on building and maintaining a high-performance JavaScript SDK that is embedded across a wide network of publisher and ad platform integrations.

You will be engineering the invisible — precise, performant, and resilient JavaScript that executes in real-time within ad environments to detect and neutralize threats before they reach end users.

The ideal candidate has a genuine passion for the craft of JavaScript at a systems level:

• Understanding the browser runtime deeply
• Obsessing over payload size and execution cost
• Building SDK distribution and versioning strategies that scale cleanly across a large, diverse customer base

Key Responsibilities

• Co-own the design, development, and ongoing maintenance of Confiant's client-side JavaScript SDK with your teammates
• Build and optimize SDK internals for maximum runtime performance — minimizing execution time, memory footprint, and impact on page load across diverse publisher environments
• Develop robust SDK versioning, deployment, and distribution strategies that allow seamless rollouts and updates across a large, heterogeneous customer base
• Translate security threat intelligence (e.g., new malvertising techniques, ad injection patterns) into SDK-level detection and blocking logic
• Instrument the SDK for observability — ensuring signals, errors, and detection events are surfaced reliably back to Confiant's backend systems
• Collaborate with the security research team to stay ahead of evolving malvertiser methods and rapidly prototype new detection heuristics
• Conduct rigorous performance profiling, benchmarking, and regression testing to ensure SDK changes never degrade customer experience
• Establish and champion SDK engineering best practices including testing strategies, documentation standards, and release processes
• Debug complex, time-sensitive production issues occurring within live ad environments across a wide range of browsers and platforms

Qualifications

• Expert-level JavaScript (ES6+) with deep knowledge of browser internals — the event loop, memory model, garbage collection, and execution context
• Strong understanding of how JavaScript executes within third-party and sandboxed environments (iframes, ad slots, cross-origin contexts)
• Proven experience building, shipping, and maintaining JavaScript SDKs or embeddable scripts at production scale
• Demonstrated ability to optimize for performance: bundle size, parse time, runtime efficiency, and network impact
• Experience with SDK distribution patterns — versioning strategies, CDN delivery, backward compatibility, and graceful degradation
• Proficiency with modern JavaScript tooling: bundlers (Webpack, Rollup, esbuild), transpilers (Babel/SWC), and testing frameworks (Jest, Playwright, or similar)
• Deep familiarity with browser security models, including same-origin policy, CSP, and cross-origin isolation

Nice to Have

• Experience in AdTech, including familiarity with ad serving infrastructure, tag management, or programmatic advertising concepts
• Background in security engineering, threat detection, or malware analysis
• Experience instrumenting client-side SDKs for telemetry and observability
• Familiarity with browser automation tools (e.g., Puppeteer, Playwright) for testing ad environments

Leveling

• Engineer IV (Staff): 6+ years of experience, with a track record of leading the technical direction of a library or SDK product. Comfortable operating as a force multiplier across the engineering team and interfacing effectively with product stakeholders.
• Engineer V (Staff): Minimum of 8+ years of experience and significant maturity solving complex problems across various technical domains, communicating with/through Product and being a force multiplier for your engineering team as well as proven experience in setting engineering practices and principles within a working environment.

Benefits

• Fully Remote
• Unlimited Paid Time Off
• Sabbatical
• Stock Option Plan
• Exceptional Health Care Plans (Medical, Dental & Vision)
• FSA & Commuter Benefits
• Employee Sponsored Disability & Life Insurance
• 401(k) Plan with Automatic Employer Contribution
• Enhanced and Extended Family Leave
• Learning & Development Budget
• Yearly Office Supply Stipend
• Free Global Co-Working Membership