Software Engineer - JavaScript SDK

About Userpilot

Userpilot is a leading product analytics and user engagement platform used by product teams at hundreds of companies to understand, segment, and activate their users. The product spans a performant JavaScript SDK that runs inside customers' web apps, a Chrome Extension for building in-app UI without code, and a React dashboard that handles complex real-time data, all backed by a distributed Elixir/Phoenix backend that sustains hundreds of thousands of concurrent WebSocket connections, high-throughput Kafka event ingestion, and real-time content delivery at scale.

We move fast, we ship often, and we believe the best engineers care as much about the product they're enabling as the systems and interfaces they build.

The Role

We are looking for a senior frontend or SDK engineer to work on our browser-based Userpilot SDK repository. This person will be responsible for the reliability, performance, release process, and long-term maintainability of the JavaScript SDK that powers in-app experiences, surveys, autocapture, session recording, checklists, resource centers, and related client-side functionality.

Responsibilities

• Own day-to-day maintenance of the SDK repository, including bug fixes, feature support, code reviews, dependency updates, and release readiness.
• Maintain and improve the SDK build system using Webpack, Babel, ESLint, and related tooling.
• Manage SDK builds, including versioning, CDN/S3 upload workflows, Cloudflare cache purging, and release validation.
• Improve SDK reliability across customer environments, including iframes, CSP constraints, browser compatibility, DOM mutation behavior, and third-party app edge cases.
• Monitor bundle size and runtime performance, and use bundle analysis to keep the SDK lightweight.
• Maintain CI/CD workflows and coordinate with the separate end-to-end Cypress test suite.
• Maintain clear technical documentation for local development, release steps, debugging, and SDK architecture.
• Collaborate with product, backend, QA, customer success, and support teams to triage production issues and deliver SDK improvements safely.

Required Skills

• Strong JavaScript experience, especially browser runtime behavior and DOM APIs.
• Experience maintaining production frontend SDKs, widgets, embeds, tracking scripts, or similar client-side libraries.
• Solid understanding of Webpack, Babel, npm, ESLint, and modern frontend build pipelines.
• Comfortable debugging issues across browsers, iframes, customer websites, CSP policies, network conditions, and asynchronous script loading.
• Experience with CI/CD, GitHub Actions, release automation, and deployment workflows.
• Strong ownership mindset: able to triage issues, prioritize risk, communicate clearly, and keep the repo healthy over time.

Nice To Have

• Experience with session replay or analytics tooling, especially rrweb.
• Experience with CDN-hosted JavaScript SDKs and cache invalidation strategies.
• Familiarity with Cypress or browser-based end-to-end testing.
• Experience modernizing JavaScript codebases incrementally.
• Knowledge of privacy, masking, consent, and data collection concerns for client-side SDKs.
  

Success Looks Like

• SDK releases are predictable, tested, and low-risk.
• Production bugs are triaged quickly and fixed with minimal regressions.
• Build and release documentation is clear enough for other engineers to follow.
• Bundle size, browser compatibility, and runtime performance are actively managed.
• The repository becomes easier to understand, test, and evolve over time.

Right to Work

Candidates must have the right to work in Ireland. We are not in a position to offer visa sponsorship for this role.

Equal Opportunities Statement

Userpilot is an equal opportunity employer. We are committed to creating an inclusive environment for all employees and applicants. We do not discriminate on the basis of gender, civil status, family status, age, disability, race, religion, sexual orientation, or membership of the Traveller community, in accordance with the Employment Equality Acts 1998-2015.

Data Privacy Notice

By applying for this role, your personal data will be processed by Userpilot for the purposes of recruitment and candidate evaluation. We will retain your information for no longer than is necessary for this purpose.