Senior Engineer - VCL Compiler
About The Position
Fastly is seeking a Compiler Engineer to join their Core Platform team. This role will focus on shaping, scaling, and maintaining the VCL Compiler (VCC) and Varnish Configuration Language (VCL). VCL is crucial for customers to configure and customize their edge logic at scale. The engineer will be responsible for evolving the language design, refactoring compiler architecture, and ensuring the stability of a codebase that processes billions of requests per second. This involves balancing the development of new language features with maintaining backward compatibility, writing robust test suites, and optimizing the C-based code generation pipeline.
Requirements
- Significant domain-relevant engineering experience (at least 5 years)
- 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
Nice To Haves
- 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
Responsibilities
- 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
Benefits
- Medical insurance
- Dental insurance
- Vision insurance
- Family planning support
- Mental health support
- Employee Assistance Program
- Life insurance
- Disability insurance
- Accident insurance
- Flexible Vacation policy
- 18 days of accrued paid sick leave
- 401(k) with company match
- Employee Stock Purchase Program
- 11 paid local holidays (for 2026)
- 12 paid company wellness days (for 2026)
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What This Job Offers
Job Type
Full-time
Career Level
Senior
Education Level
No Education Listed
