Senior Software Engineer, Browser Automation

Horizon3, US, Remote

What you will do

Help us grow and harden our browser automation and crawling engine, which is 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 the gnarly realities of modern web apps: SPA routing and hydration timing, authenticated sessions, multi-step flows, file uploads, WebSocket/Socket.IO http://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. This involves endpoint and parameter discovery, dedupe, queueing, and state management, while keeping everything production-safe and side-effect-aware.
Help draw the line between deterministic automation and LLM-driven navigation, applying models surgically rather than as a default, and keeping the system fast, debuggable, and cheap to run.

Posted pay

$199K–$235K

a year

This base pay is above the median for senior software engineering jobs that are remote in the US.

We compare the middle of each posted range. This is base pay as posted. The group does not include this job.

Location

US, Remote

Work type

Remote

Level

Senior

Posted

Jun 23, 2026

Last check

12 h ago

Job type

Software engineering

What you will do

Help us grow and harden our browser automation and crawling engine, which is 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 the gnarly realities of modern web apps: SPA routing and hydration timing, authenticated sessions, multi-step flows, file uploads, WebSocket/Socket.IO http://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. This involves endpoint and parameter discovery, dedupe, queueing, and state management, while keeping everything production-safe and side-effect-aware.
Help draw the line between deterministic automation and LLM-driven navigation, applying models surgically rather than as a default, and keeping the system fast, debuggable, and cheap to run.