Apply on Employer Site

ZenRows · 3 months ago

Senior Software Engineer - Browser

United States

Full-time

Remote

Senior Level

5+ years exp

ZenRows is a rapidly growing startup based in Bilbao, focused on transforming data workflows through advanced web data extraction tools. They are seeking a Senior Software Engineer to enhance their browser technology, ensuring it remains undetectable by anti-bot systems, while also developing internal tools for automation and analysis of bot challenges.

Big DataCloud Data ServicesData IntegrationData MiningInformation TechnologySaaSSoftware

Responsibilities

Own and evolve our Chromium fork, maintaining full control over browser behavior and instrumentation

Patch and neutralize browser fingerprinting surfaces: canvas, audio, WebGL, screen, navigator, user agent, and more

Harden the browser against integrity checks (function.toString, error stack traces, memory layout, etc.)

Ensure parity with real users under advanced detection tools like FingerprintJS, Datadome, PerimeterX, and others

Analyze real-world JavaScript challenges and traps designed to detect bots

Reverse engineer obfuscated payloads and evasive scripts using tools like Chrome DevTools, Frida, Wireshark, mitmproxy, etc

Build internal tooling to automatically detect, triage, and solve bot challenges, integrating into our scraping runtime

Develop detection signatures for new anti-bot mechanisms and continuously track vendor evolution

Build robust internal libraries to spoof browser behavior, intercept and manipulate DOM/state, and bypass anti-bot logic

Create automated pipelines that detect detection, trigger browser patches, or escalate to manual review

Integrate JavaScript instrumentation and DOM mutation trackers to flag stealth issues before customers do

Build internal dashboards to monitor fingerprint mismatches, challenge rates, JS errors, and detection spikes

Proactively identify and mitigate stealth regressions caused by Chromium updates or vendor changes

Help maintain and evolve our internal stealth testbed, simulating dozens of anti-bot vendor environments

Be the team’s go-to expert in browser internals, bot detection evasion, and security-focused reverse engineering

Mentor engineers in topics like V8 internals, JS fingerprinting, and browser automation stealth

Help define our long-term strategy around browser-level evasion and undetectable scraping at scale

Qualification

C++JavaScriptChromium internalsReverse engineeringBrowser automationJavaScript fingerprintingDebugging skillsAgile mindsetTechnical leadershipCommunication skills

Required

5+ years of software engineering with a focus on browsers, reverse engineering, or automation in adversarial environments

Fluency in C++ and JavaScript (Node or browser), with ability to write clean, testable low-level code

Deep understanding of Chromium internals: Blink, V8, DevTools Protocol, browser architecture, etc

Proven experience patching Chromium or building hardened browser automation setups (e.g., stealth plugins, puppeteer-core forks)

Advanced knowledge of JavaScript fingerprinting, detection vectors, and browser inconsistencies

Familiarity with anti-bot vendors like PerimeterX, Datadome, Kasada, Akamai Bot Manager, and FingerprintJS

Strong debugging and tooling skills: Chrome DevTools, Wireshark, mitmproxy, Frida, Objection, or similar

Experience automating evasion workflows and detection pipelines is a major plus

Communicate clearly, document thoroughly, and guide complex decisions across teams

Preferred

Have built your own Chromium fork or stealth layer from scratch

Have hands-on experience defeating real anti-bot challenges and captcha solving in production environments

Know how to simulate mouse/keyboard behavior and DOM interaction that mimics real humans

Have published research or tools related to browser automation, anti-bot evasion, or JavaScript analysis

Knowledge of WebAssembly, memory layout inspection, syscall monitoring, or other stealth-adjacent low-level domains

Benefits

100% remote work: We are a company that offers true freedom. Work wherever life takes you.

The salary you are worth: We never ask people what they are earning, but instead what they are looking for. If your ability and experience justifies it and we think you will help us succeed, then we will match your expectations.

The equipment you want: We believe in giving our people the tools they need to succeed and don’t have a default machine to give you.

Generous Learning & Development budget: We believe in always adding value to our top performers and helping them grow their skills in a direction that is beneficial both to them and the business

All-Star Awards: We recognize achievements in many ways within the business, but the bi-annual All-Star Awards allow the CEO to tailor reward packages to the person. Whether this is a holiday destination of choice, a learning course that adds value or something else.. We believe in getting to know every employee personally.

BitWarden Account: With employees working remotely worldwide, we are keen to ensure we empower them with tools to keep passwords as secure as possible.

Charity Initiatives: We are a business that believes in giving back to the community, and every year, we allow our employees the opportunity to give back.

Annual Kick-Off: We want our employees to see where ZenRows was born and enjoy all the Pintxos they can handle.

Share in Our Success: We want our top performers to be part of the company's success and offer opportunities for stock option allocation when people show their value.

Deel Benefits: As a fully remote organization, we employ our people via Deel. This brings freedom of location and many other benefits, including discounts on VPNs, memberships and services.