Sr./ Staff JavaScript Developer - Web SDK w Polska

About Oscilar

At Oscilar, we're building the most advanced AI Risk Decisioning™ Platform. Banks, fintechs, and digitally native organizations rely on us to manage their fraud, credit, and compliance risk with the power of AI.

Role Description

We are seeking a highly skilled Staff JavaScript Developer to design, build, and optimize our Web SDK. This SDK will be at the core of our solutions for device fingerprinting, identity verification, and behavior analytics, enabling our customers to stay ahead in the ever-evolving fraud prevention landscape. This is not a UI or App development role, this is building SDKs for detecting fraud by analyzing device and behavioral properties. This requires deep understanding of the platform internals.

As a Staff Developer, you will lead the design, development, and performance optimization of our Web SDK, leveraging your deep expertise in JavaScript, TypeScript, and modern web technologies. You will collaborate across teams to deliver a secure, scalable, and developer-friendly SDK.

Responsibilities

• Lead the development and maintenance of a high-performance Web SDK for collecting and analyzing browser and device-related data.
• Design and implement algorithms to create unique device fingerprints and capture behavior-based insights (e.g., gestures, keyboard, and mouse interactions).
• Build and maintain a robust CI/CD pipeline with automated cross-browser testing and release cycles.
• Continuously optimize SDK performance to minimize resource usage and ensure a seamless user experience.
• Stay updated on emerging web technologies, security practices, and industry trends to enhance SDK capabilities.
• Develop clean, maintainable, and well-documented code aligned with the best coding practices.
• Conduct thorough code reviews and mentor junior engineers on best practices.
• Collaborate with cross-functional teams—including product managers, designers, and QA engineers—to meet high-quality standards and customer requirements.
• Ensure data privacy and security principles are embedded in the SDK’s design and implementation.
• Drive innovation in browser-based solutions for risk, fraud detection, and device analytics.

Why join us

• Mission-driven teams: Work alongside industry veterans from Meta, Uber, Citi, and Confluent, all united by a shared goal to make the digital world safer.
• Ownership and impact: We believe in extreme ownership. You'll be empowered to take responsibility, move fast, and make decisions that drive our mission forward.
• Innovate at the cutting edge: Your work will shape how modern finance detects fraud and manages risk.

Benefits

• Compensation : Competitive salary ($180K – $262.5K) and equity packages, including a 401k
• Flexibility : Remote-first culture — work from anywhere
• Health : Comprehensive health, dental, and vision insurance with a top tier plan for you and your dependents (US)
• Balance : Unlimited PTO policy
• * Technical: * AI First company; both Co-Founders are engineers at heart; and over 50% of the company is Engineering and Product
• Culture : Family-Friendly environment; Regular team events and offsites
• Development : Unparalleled learning and professional development opportunities
• Impact: Making the internet safer by protecting online transactions

Technical Skills

• Proficiency: JavaScript (ES6+), TypeScript, REST APIs, Git, and version control tools.
• Web SDK Expertise: Extensive experience designing and maintaining Web SDKs or libraries with a focus on data collection, tracking, or analytics.
• Browser APIs: Deep understanding of browser environments, APIs, and efficient handling of browser-related data.
• Security Principles: Strong knowledge of data privacy, encryption, hashing, and obfuscation techniques.
• Cross-browser Compatibility: Experience in building solutions that work seamlessly across various browsers and devices.
• Server-side Familiarity: Understanding of server-side technologies and RESTful APIs for data retrieval and storage.
• Build Tools: Proficiency in modern build tools and frameworks like Webpack, Babel, or Rollup.

Soft Skills

• Excellent problem-solving abilities, with attention to detail and a focus on delivering high-quality solutions.
• Strong communication and collaboration skills to work effectively in cross-functional teams.
• Ability to mentor and provide constructive feedback to junior developers.

Education & Experience

• Bachelor’s degree in computer science, Software Engineering, or a related field (or equivalent experience).
• 8+ years of experience in web development, with at least 3 years focused on building and maintaining SDKs.
• Proven track record of contributing to open-source projects or showcasing relevant work on platforms like GitHub.

Preferred Qualifications

• Experience with AI-driven analytics, risk systems, or fraud prevention technologies.
• Familiarity with JavaScript SDKs, gestures, and interaction data processing.
• Prior experience in a high-scale, distributed environment.