Senior Front End Engineer

Sr. Frontend Engineer, Ketch SDKs

As a Sr. Frontend Engineer, Ketch SDKs, you'll own the runtime that powers the modern internet. You'll design and maintain SDKs that process millions of events per day and emit billions of signals to platforms like Google, Meta, Snowflake, Datadog, and Full Story enabling data collection that respects user choices while powering the modern ad-tech ecosystem. Every network request, every consent signal, every event flows through the infrastructure you build. If Ketch ever goes down, major platforms you use daily may go down with it. The stakes are real. This is infrastructure at an impossible scale, in the hardest runtime environment imaginable. You'll tackle performance, privacy, and reliability head-on, building systems that can't fail and architectures that ripple through Fortune 500 production environments. We operate with deep personal ownership which means that you'll solve problems from first principles, drive end-to-end solutions, and define the technical direction for client-side data governance at scale. You'll design SDKs used by thousands of engineers, integrating with the entire web and mobile stack, shaping the backbone of a free and fair internet.

Tech Stack

• Frontend: TypeScript, React, Rollup, ESBuild, Jest, Playwright
• Infrastructure: AWS (Lambda, CloudFront, S3), Docker, Terraform
• Integrations: Google Analytics, Meta, Snowflake, Datadog, FullStory, 100+ other platforms
• Observability & Telemetry: Datadog, Sentry, custom pipelines processing billions of events daily
• CI/CD & Delivery: GitHub Actions, automated pipelines, feature flags
• Mobile / Cross-Platform: iOS/Android SDKs, React Native (plus polyfills and platform-specific optimizations)

Top Skills

• Front End React
• SDK
• Excellent communication skills, dynamic personality
• Ability to work in a fast-paced start-up environment
• Start-up experience highly preferred
• Recent/extensive experience in permanent roles to ensure long-term stability and commitment

Ketch is a Series B, well-funded startup that's focused on developing first-in class innovation around the domain of data management and privacy. Our vision is an intelligent, pervasive data fabric that respects the data rights of people and businesses. We envision a world in which societies, governments, businesses, and citizens move from rules to tools that respect our data dignity, and enable all stakeholders to responsibly harvest the gains of a data-driven economy. Ketch gives businesses and software engineers a coordinated set of APIs, applications, and infrastructure to help businesses exert perfect control over every scrap of responsibly gathered data.

Additional Skills & Qualifications

What You'll Own

• Design and evolve the core Ketch SDK runtime for consent orchestration, event tracking, rule evaluation, and platform integration at massive scale.
• Optimize SDK performance under impossible constraints and enforce deterministic client-side data governance across 50+ browsers/OS combinations, intercepting and managing network requests, cookies, and storage.
• Build APIs and tooling for thousands of engineers, making complex integrations simple, secure, and impossible to misuse.
• Extend SDKs for custom integrations, multi-platform routing, adtech connectivity, and AI-driven privacy telemetry.
• Simulate real-world network interactions with emulators and pipelines that feed AI models for privacy risk detection.
• Collaborate across product, design, and customer success, mentor engineers, and drive architectural excellence across the frontend team.

What We're Looking For

• Deep expertise in JavaScript & TypeScript (ES6+), browser APIs, event loops, closures, and high-performance client-side coding across diverse runtime environments.
• Proven experience building SDKs and JavaScript tags deployed on customer websites, integrating with internal and external platforms under production pressure.
• Mastery of browser architecture and client-side systems: rendering pipeline, network stack, storage APIs, cross-origin communication, and deterministic data flow governance.
• Performance and reliability wizardry: profiling, benchmarking, optimizing, and debugging async race conditions across distributed client-side systems.
• Systems thinking and build tooling experience: Webpack, Rollup, ESBuild, ESM/CommonJS/UMD, polyfills, and managing browser inconsistencies or third-party script conflicts.
• Collaboration, mentorship, and product-minded ownership: articulate technical decisions, influence stakeholders, drive pragmatic solutions, and elevate teams through code reviews and knowledge sharing.
• Bonus skills: mobile SDKs (iOS/Android/React Native), ad-tech

VERY IMPORTANT: ++Must be authorized to work in the United States without sponsorship++.

Job Type & Location

This is a Contract position based out of San Francisco, CA.

Pay and Benefits

The pay range for this position is $160000.00 - $200000.00/yr. Medica, dental, vision, life

Workplace Type

This is a hybrid position in San Francisco, CA.

Application Deadline

This position is anticipated to close on Jan 11, 2026.