Senior Engineer - VCL Compiler

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 You'll 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 don't 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 We're 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

We’ll 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 $181,220 to $217,464.

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 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.