Senior Software Engineer (Contract)

Remote from: Germany
Annual salary: Undisclosed
Salary information is not provided for this position. Check our Salary Directory to estimate the average compensation for similar roles.
Department: Software Engineering
Employment type: Contract,
Job posted: 9 Jun 2026
Apply before: 9 Jul 2026
Experience level: Senior
Views / Applies: 12 / 0

About company

About Mozilla

Feel good about your work again.

Computer Software
2005

Actively Hiring

AI Summary

Mozilla seeks a Senior Software Engineer to join the Privacy Team, focusing on implementing privacy-improving and anti-tracking features in the Firefox web browser. The role involves architectural improvements in the Gecko engine and requires expertise in C++, Rust, and JavaScript. The position is contract-based, geographically distributed, and requires strong communication skills. Ideal candidates have experience with browser engines, memory safety, and multi-threaded systems. This role offers the opportunity to make a positive impact on web privacy and user protection.

Role DNA

Job Complexity

Easy Hard

Pace & Pressure

Relaxed Fast-paced

Autonomy Level

Guided Full Ownership

Communication Load

Independent Highly Collaborative

AI Insight The role requires senior-level expertise in C++ and Rust, deep understanding of browser architecture, and the ability to independently scope and land complex features within tight release windows, indicating high difficulty.

Salary Analysis

AI Insight The offered salary is not specified, but for a Senior Software Engineer role in the US, the market range typically spans $130,000 to $230,000 annually, with a median around $180,000. Contract positions may offer higher hourly rates but lack benefits. Mozilla's compensation is typically competitive within the industry.

Key Skills

C++ Rust JavaScript Browser Architecture Privacy Anti-tracking Gecko Memory Safety Multi-threaded Programming Asynchronous Communication

Cover Letter Sample

I am excited to apply for the Senior Software Engineer (Contract) position on the Privacy Team at Mozilla. With over 4 years of experience in C++ and Rust, a strong background in memory safety and multi-threaded systems, and a passion for protecting user privacy, I am eager to contribute to advancing Firefox's web platform.

My previous work includes implementing anti-tracking features and optimizing data sanitization in large-scale projects, aligning closely with the responsibilities outlined. I thrive in geographically distributed, asynchronous teams and have a proven track record of independently scoping and delivering complex features within tight timelines.

I am particularly drawn to Mozilla's mission of building an open and accessible internet, and I believe my technical skills and commitment to privacy can make a meaningful impact. I look forward to the opportunity to discuss how my experience aligns with your team's goals.

Possible Interview Questions

Can you describe your experience with implementing privacy-improving features in a web browser or similar system?

I have worked on a team that integrated anti-tracking mechanisms into a browser engine, focusing on blocking fingerprinting and third-party cookies. I implemented data sanitization routines in C++ and Rust, ensuring minimal performance impact while effectively preventing user tracking.

How do you approach architectural improvements in a complex codebase like Gecko?

I start by understanding the current architecture through code review and documentation, then identify pain points. I propose incremental changes, prototype them, and gather feedback. I prioritize changes that offer the most benefit with minimal disruption, and I ensure thorough testing.

Describe a time you had to independently scope and land a complex feature within a tight release window.

In my previous role, I was tasked with adding a new security feature that required changes across multiple modules. I broke the work into smaller milestones, communicated progress daily, and coordinated with QA. I completed the feature two weeks before the release freeze, allowing time for integration testing.

How do you ensure code quality and maintainability when working with memory-unsafe languages like C++?

I follow strict coding standards, use static analyzers, and conduct regular code reviews. I also leverage Rust's memory safety in areas where it's feasible. I write extensive unit tests and use sanitizers to catch memory issues early.

How do you handle communication and collaboration in a geographically distributed team?

I rely on async communication tools like Slack and email for documentation of decisions, and schedule regular video calls for complex discussions. I provide clear status updates and document my work to keep everyone aligned. I also make an effort to understand time zone differences and respect colleagues' working hours.

Are you passionate about Privacy Protections and the Open Web? Do you want to ship software to a large user base? Do you want your contributions to have a positive impact on the world? Do you want to advance current browser architecture to make the web a safer place for users?

Mozilla exists to build the Internet as a public resource accessible to all because we believe that open and free is better than closed and restricted. We are looking for a Senior Software Engineer to support the Privacy Team to advance the Firefox Web Platform.

As a Senior Software Engineer in the Privacy Team at Mozilla, you will…

Implement Privacy-improving, anti-tracking features and data sanitization into the Firefox web browser to prevent all forms of unhealthy user tracking.
Implement architectural improvements into Gecko, the browser engine underlying Firefox.
Build performant, low-latency, and maintainable C++, JavaScript and Rust code
Work as part of a geographically distributed team in an asynchronous manner (mostly Europe and US-East).

Your Professional Profile:

Bachelor’s degree in computer science, engineering, or a related program; or equivalent work experience.
At least 4 years of experience with programming in C++ and Rust, with a strong background in memory safety, multi-threaded system architecture, or raw data stream manipulation
Proven ability to onboard quickly, deliver and improve complex software projects.
Proven track record of independently scoping and landing complex features within tight release windows.
Excellent written and verbal communication skills. You can validate your progress and decisions and communicate them clearly.

Bonus Points:

You have already contributed to the Mozilla mission and the codebase.
Experience working within the browser space (Gecko, Chromium, WebKit) or web engine runtime abstractions.
Experience or high interest in designing or leveraging ML pipelines to automate internal developer workflows.
Deep understanding of web architecture, the privacy/security model of the web, and client-side data structures.
Knowledge of basic statistical modeling.
Proficiency with Python and SQL.

About Mozilla

Mozilla exists to build the Internet as a public resource accessible to all because we believe that open and free is better than closed and controlled. When you work at Mozilla, you give yourself a chance to make a difference in the lives of Web users everywhere. And you give us a chance to make a difference in your life every single day. Join us to work on the Web as the platform and help create more opportunity and innovation for everyone online.

Commitment to diversity, equity, inclusion, and belonging

Mozilla understands that valuing diverse creative practices and forms of knowledge are crucial to and enrich the company’s core mission. We encourage applications from everyone, including members of all equity-seeking communities, such as (but certainly not limited to) women, racialized and Indigenous persons, persons with disabilities, persons of all sexual orientations, gender identities and expressions.

We will ensure that qualified individuals with disabilities are provided reasonable accommodations to participate in the job application or interview process, to perform essential job functions, and to receive other benefits and privileges of employment, as appropriate. Please contact us at [email protected] to request accommodation.

We are an equal opportunity employer. We do not discriminate on the basis of race (including hairstyle and texture), religion (including religious grooming and dress practices), gender, gender identity, gender expression, color, national origin, pregnancy, ancestry, domestic partner status, disability, sexual orientation, age, genetic predisposition, medical condition, marital status, citizenship status, military or veteran status, or any other basis covered by applicable laws. Mozilla will not tolerate discrimination or harassment based on any of these characteristics or any other unlawful behavior, conduct, or purpose.

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