Horizon3.ai

4 weeks ago

Senior Software Engineer, Browser Automation

✓ Verified Job

Canonical indexed version, validated from employer's careers page.

Source: Company careers pageValidated by: Fursa AI

Last checked: 12 hours agoStatus: Live

Job Summary

Join Horizon3.ai to build and scale the browser automation and crawling engine for an autonomous, production-safe web application pentest platform. You’ll advance Playwright-based crawling, tackle complex SPA and auth scenarios, improve coverage and throughput, and blend deterministic automation with selective LLM-driven navigation in a security-focused, distributed system.

Location: United States

Workplace: Remote

Employment Type: Full time

Job Function: Software Engineering

Key Responsibilities

•Grow and harden our browser automation and crawling engine—the layer that discovers, navigates, and interacts with target applications before and during an autonomous pentest.
•Advance our browser-driven crawler using Playwright and Stagehand.
•Tackle modern web app realities: SPA routing/hydration timing, authenticated sessions, multi-step flows, file uploads, WebSocket/Socket.IO traffic, infinite scroll, and crawler traps.
•Extend our agentic login and authentication capabilities, including complex auth flows, MFA/TOTP, and credentialed access reliable enough to run unattended against customer environments.
•Improve crawl coverage, determinism, and throughput through endpoint and parameter discovery, dedupe, queueing, and state management while keeping production-safety in mind.

Pay and Benefits

Salary: USD 169,000 - 208,000 annually

Equity and Bonus:Equity

Perks:Health InsuranceVisionDentalParental LeaveEquity

Key Requirements

•Experience building production software with deep hands-on browser automation (Playwright, Puppeteer, or Selenium) against real, non-trivial web applications.
•Strong TypeScript / Node.js skills and comfort with the headless-browser stack, including Chromium internals, Chrome DevTools Protocol, network interception, the DOM, and JS execution contexts.
•Track record of taming flaky, stateful, JavaScript-heavy apps; you’ve fought SPA timing, authentication, and anti-automation defenses.
•Solid instincts for distributed/concurrent systems: queues, backpressure, retries, idempotency, and running many browser sessions reliably at scale.
•Bias toward determinism and debuggability; judgment to reach for an LLM only when a deterministic approach genuinely can’t do the job.

Experience:CybersecuritySaaS

Skills:OwnershipCollaborationProblem-solvingCommunicationPrioritization

Languages:English

Tech Stack:PlaywrightStagehandTypeScriptNode.jsChromiumChrome DevTools ProtocolSocket.IOLLMsPuppeteerSelenium

Company Brief

Horizon3.ai

Builds NodeZero®, an autonomous penetration-testing platform that continuously finds, prioritizes, and verifies exploitable vulnerabilities across on-premises, cloud, and hybrid environments to help organizations reduce security risk.

Industry: Cybersecurity

Company Size: Large (251 to 1,000 employees)

Growth: Scaleup

Funding: Series D

Headquarters: San Francisco, United States

Founded: 2019

Glassdoor: 4.9

Website LinkedIn Glassdoor

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Horizon3.ai

4 weeks ago

Senior Software Engineer, Browser Automation

✓ Verified Job

Canonical indexed version, validated from employer's careers page.

Source: Company careers pageValidated by: Fursa AI

Last checked: 12 hours agoStatus: Live

Job Summary

Location: United States

Workplace: Remote

Employment Type: Full time

Job Function: Software Engineering

Key Responsibilities

•Grow and harden our browser automation and crawling engine—the layer that discovers, navigates, and interacts with target applications before and during an autonomous pentest.
•Advance our browser-driven crawler using Playwright and Stagehand.
•Tackle modern web app realities: SPA routing/hydration timing, authenticated sessions, multi-step flows, file uploads, WebSocket/Socket.IO traffic, infinite scroll, and crawler traps.
•Extend our agentic login and authentication capabilities, including complex auth flows, MFA/TOTP, and credentialed access reliable enough to run unattended against customer environments.
•Improve crawl coverage, determinism, and throughput through endpoint and parameter discovery, dedupe, queueing, and state management while keeping production-safety in mind.

Pay and Benefits

Salary: USD 169,000 - 208,000 annually

Equity and Bonus:Equity

Perks:Health InsuranceVisionDentalParental LeaveEquity

Key Requirements

•Experience building production software with deep hands-on browser automation (Playwright, Puppeteer, or Selenium) against real, non-trivial web applications.
•Strong TypeScript / Node.js skills and comfort with the headless-browser stack, including Chromium internals, Chrome DevTools Protocol, network interception, the DOM, and JS execution contexts.
•Track record of taming flaky, stateful, JavaScript-heavy apps; you’ve fought SPA timing, authentication, and anti-automation defenses.
•Solid instincts for distributed/concurrent systems: queues, backpressure, retries, idempotency, and running many browser sessions reliably at scale.
•Bias toward determinism and debuggability; judgment to reach for an LLM only when a deterministic approach genuinely can’t do the job.

Experience:CybersecuritySaaS

Skills:OwnershipCollaborationProblem-solvingCommunicationPrioritization

Languages:English

Tech Stack:PlaywrightStagehandTypeScriptNode.jsChromiumChrome DevTools ProtocolSocket.IOLLMsPuppeteerSelenium

Company Brief

Horizon3.ai

Industry: Cybersecurity

Company Size: Large (251 to 1,000 employees)

Growth: Scaleup

Funding: Series D

Headquarters: San Francisco, United States

Founded: 2019

Glassdoor: 4.9

Website LinkedIn Glassdoor