Principal Engineer

Fastly; City Of London; Hybrid; GBP 102,000 - 123,000; Full time

Job summary

A leading cloud technology company in London is seeking a Principal Software Engineer to enhance core edge systems. The ideal candidate will lead projects, optimize network protocols, and collaborate across teams. Required experience includes coding in C, C++, and Rust, with at least 10 years in the field. This position is hybrid and offers a salary range of $134,763 to $161,716 based on experience.

Benefits

Comprehensive benefits package

Equity and discretionary bonus programs

Flexible work environment

Qualifications

• 10+ years of relevant engineering experience.
• Proven ability to design & implement reliable, scalable, low-latency systems.
• Excellent communication skills and ability to produce documentation.

Responsibilities

• Lead full-lifecycle projects from architecture to deployment.
• Write, test, and deploy C, Rust, and Go code.
• Enhance and optimize network protocols like TCP and QUIC.

Skills

C

C++

Rust

Linux systems

Network programming

Tools

Git

Compilers

Job description

Fastly helps people stay better connected with the things they love. Fastlys edge cloud platform enables customers to create great digital experiences quickly, securely and reliably by processing, serving and securing our customers applications as close to their end-users as possible at the edge of the Internet. The platform is designed to take advantage of the modern internet to be programmable and to support agile software development. Fastlys customers include many of the worlds most prominent companies including Vimeo, Pinterest, The New York Times and GitHub.

We're building a more trustworthy Internet. Come join us.

Principal Software Engineer – Edge Systems

The Edge Systems Team develops software that interacts with the full systems stack of Fastlys infrastructure from the kernel up to core systems software. Projects range from implementing new protocols, optimizing kernel‑userspace communication, routing among the edge nodes, designing distributed systems and more. We expect this position to focus on enhancing our overall core edge systems with respect to efficiency, performance and resilience. We are looking for a Principal Software Engineer passionate about applying their to the Internet fast and reliable.

What You’ll Do

• Lead full‑lifecycle projects from architecture & design to deployment in support of Fastly's edge systems.
• Write, test and deploy C, Rust and Go code.
• Enhance, maintain and optimize network protocols such as TCP and QUIC.
• Work across layers from the Linux kernel to the core edge systems and control planes.
• Collaborate with cross‑functional teams and stakeholders to shape a clear technical roadmap, prioritizing key initiatives and proactively identifying and mitigating risks to deploy, support, troubleshoot and deliver features to customers.

Contribute to open source projects such as h2o and picotls

Mentor and support the professional growth of engineers fostering a culture of respect, knowledge sharing, innovation and collaboration within the team.

What We’re Looking For

• Proven ability to design & implement reliable, scalable, low‑latency systems. Most Principal Engineers at Fastly have at least 10 years of domain‑relevant engineering experience.
• Significant production experience with coding in C, C++ and/or Rust.

Experience with Linux systems and network programming

• Hands‑on experience in building distributed infrastructure and maintaining it over time.
• Advanced knowledge of Linux as a development environment: git, compilers, etc.
• Excellent written and verbal communication skills with the ability to produce clear and comprehensive documentation.
• A collaborative mindset with experience working across cross‑functional teams fostering a culture of respect, knowledge sharing and innovation.
• Proven ability to mentor and support the growth of engineers both within a specific area of expertise and more broadly.

We value a variety of voices so this is not a laundry list. It would be an added bonus if you have experience in any of the following:

• Web / Internet protocols such as TCP, HTTP, TLS, DNS, QUIC.
• Understanding of datapath mechanisms such as eBPF and DPDK.
• Ability to systematically profile and benchmark complex cross‑layer distributed systems.
• Understanding of how customers will interact with features you develop.
• Comfortable working in a geographically distributed team and highly available environments.

Work Hours

This position will require you to be available during core business hours and occasionally nights and weekends as required for on‑call support.

Work Location(s) & Travel Requirements

This position is open to hybrid work locations only. The preferred locations for this position are London, UK. Fastly currently embraces a largely hybrid model for most roles which allows employees flexibility to split their time between the office and home. We are not considering remote applicants at this time. This position may require travel as required by your role or requested by your manager.

Salary:

The estimated salary range for this position is $134,763 to $161,716. Starting salary may vary based on permissible non‑discriminatory factors such as experience, skills, qualifications and location. This role may be eligible to participate in Fastly's equity and discretionary bonus programs.

Benefits

We care about you. Fastly works hard to create a positive environment for our employees and we think your life outside of work is important too. We support our teams with great benefits that start on the first day of your employment with Fastly. Curious about our offerings? We offer a comprehensive benefits package designed to meet your needs. Our offerings may vary depending on the country where you work and are subject to change.

Why Fastly

We have a huge impact. Fastly is a small company with a big reach. Not only do our customers have a tremendous user base but we also support a growing number of open‑source projects and, of code employees are encouraged to share causes close to their heart with others so we can help lend a supportive hand.

We love distributed teams. Fastly's home‑base is in San Francisco but we have multiple offices and employees sprinkled around the globe. As a new hire you will be able to attend our IN‑PERSON new hire orientation in our San Francisco office! It is an exciting week‑long experience that we offer to new employees to build connections with colleagues across Fastly, participate in hands‑on learning opportunities and immerse yourself in our culture firsthand.

We value diversity. Growing and maintaining our inclusive and diverse team matters to us. We are committed to being a company where our employees feel comfortable bringing their authentic selves to work and have the ability to be successful every day.

We are passionate. Fastly is chock full of passionate people and we're not one size fits all. Fastly employs authors, pilots, skiers, parents (of humans and animals), makeup geeks, coffee connoisseurs and more. We love employees for who they are and what they are passionate about.

We're always looking for humble, sharp and creative folks to join the Fastly team. If you think you might be a fit, please apply! A fully completed application and resume or CV are required when applying.

Fastly is committed to ensuring equal employment opportunity and to providing employees with a safe and welcoming work environment free of discrimination and harassment. Our employment decisions are based on business needs, job requirements and individual qualifications. All qualified applicants will receive consideration for employment without regard to age, ancestry, color, family or medical care, leave, gender identity or expression, genetic information, marital status, medical condition, national origin, family or parental status, physical or mental disability, political affiliation, protected veteran status, race, religion, sex (including pregnancy), sexual orientation or any other characteristic protected by applicable laws, regulations and ordinances.

Consistent with the Americans with Disabilities Act (ADA) and federal or state disability laws Fastly will provide reasonable accommodations for applicants and employees with disabilities. If reasonable accommodation is needed to participate in the job application or interview process to perform essential job functions and/or to receive other benefits and privileges of employment, please contact your Recruiter or the Fastly Employee Relations team at ________.

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