Senior Engineer VCL Compiler

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 GitHub Yelp Paramount and JetBlue.

Were building a more trustworthy Internet. Come join us.

Posting Open Date: Aug. 4 2026

Anticipated Posting Close Date*: Aug. 17 2026

*Job posting may close early due to the volume of applicants.

Sr Software Engineer VCL Compiler

We are looking for a Compiler Engineer to join our Core Platform team to help shape scale and maintain the VCL Compiler (VCC) and Varnish Configuration Language (VCL). VCL is at the heart of how our customers configure and customize their edge logic at scale.

In this role you will be responsible for evolving the language design refactoring compiler architecture and ensuring the absolute stability of a codebase that processes billions of requests per second. You will balance building innovative language features with the meticulous detail-oriented work of maintaining backward compatibility writing robust test suites and optimizing our C-based code generation pipeline.

What Youll Do:

• Design and implement VCL language extensions syntax updates and new compiler features
• Parsing and AST rework to improve long-term maintainability of the compiler
• Refactor and modularize the existing compiler codebase to reduce complexity and improve stability
• Own the testing and validation pipeline to ensure compiler changes dont break existing customer code
• Collaborate with cross-functional teams to align on architecture and technical direction
• Write clear technical documentation for internal teams and external users

What Were Looking For:

• Significant domain-relevant engineering experience - Most Senior Engineers at Fastly have at least 5 years of related experience.
• Significant production experience writing C with knowledge of POSIX/Linux environments
• Solid understanding of compiler internals: parsing AST design intermediate representations code generation
• Experience simplifying and refactoring established codebases while maintaining backward compatibility
• Track record of comprehensive testing practices CI/CD and treating the build pipeline as production infrastructure
• Good written communication skills with the ability to produce clear technical documentation
• A collaborative mindset with experience working across cross-functional teams

Well be super impressed if you have experience in any of these:

• Previous Fastly engineering experience
• Contributions to open source compiler or language projects
• Familiarity with Varnish VCL or CDN/edge computing infrastructure
• Background in domain-specific language (DSL) design

Work Hours:

• This position will require you to be available during core business hours. It may also require occasional nights and weekends as necessary to support any on-call coverage.

Work Location(s) & Travel Requirements:

The preferred locations for this position are:

• New York NY
• Denver CO
• San Francisco CA

Fastly currently embraces a largely hybrid model for most roles which allows employees flexibility to split their time between the office and home.

There is a strong preference for Hybrid near a local office. However we may be willing to consider exceptionally qualified remote candidates within the US.

This position may require travel as required by your role or requested by your manager.

SF / LA Fair Chance Ordinance Statement

Pursuant to the San Francisco Fair Chance Ordinance and the Los Angeles Fair Chance Initiative for Hiring Ordinance we will consider for employment qualified applicants with arrest and conviction records.

Salary:

The estimated salary range for this position is $181220 to $217464.

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 Fastlys 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 including medical dental and vision insurance. Family planning mental health support along with Employee Assistance Program Insurance (Life Disability and Accident) a Flexible Vacation policy and up to 18 days of accrued paid sick leave are there to help support our employees. We also offer 401(k) (including company match) and an Employee Stock Purchase Program. For 2026 we offer 11 paid local holidays 12 paid company wellness days.

Why Fastly

• We have a huge impact.Fastly is a small company with a big reach. Not only doour customershave a tremendous user base but we also support a growing number ofopen 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 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 were 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.

Were 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.

All job applications must be submitted through our official careers site at We will never request sensitive information such as your Social Security number bank account or credit card information during the application process. All official communication will come from an @ or @ email address.

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 or .

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