Senior Backend Software Engineer

Who you are

• Hands-on experience designing and building reliable, large-scale backend systems - most Senior Engineers at Fastly have at least 5 years of relevant experience
• 5+ years shipping production Go as your primary language
• 3+ years on public APIs with external consumers. You've shipped a breaking change to customers who'd already integrated against your API. You've written a deprecation notice that actually went out
• You drive projects, not just tasks. You've owned a multi-week effort end-to-end: design doc through post-launch
• Good judgement on RESTful API design: resource modeling, versioning, idempotency, error semantics, pagination, OpenAPI. You've made one of these calls wrong in production and remember what it cost to clean up
• You design for the people downstream of your API. The customer hitting your endpoint at 3am, the support engineer debugging their escalation, the frontend teammate integrating against your contract. You've watched a vague error message of yours confuse someone and changed how you write them since
• Testing and observability as subtraction, not addition. You can name a metric you added that paid off — and one you'd delete now
• Coding agents as a daily driver, not reluctantly. This team uses them heavily
• Built or operated security products (WAF, bot, DDoS, app security)
• Working knowledge of auth at API scale (RBAC, OAuth, JWT, SAML)
• This position will require you to be available during core business hours (Pacific Time) and occasional nights and weekends as required for on call support

What the job involves

• Some of the largest sites on the internet trust Fastly to keep them safe. The Security Products Console team owns the public-facing interface they use to do it - configuring Next-Gen WAF, DDoS protection, Bot Management, and the products we're building next
• Our APIs meet critical business needs. Customers deploy them during active attacks, automate them through Terraform and CI/CD, and build entire security workflows on top of them. When the threat landscape moves, our APIs are how customers move with it. A bad release here leaves them exposed when they need us most: a great one is invisible, and that's the bar
• We're hiring as the API surface scales for new product launches and a growing developer ecosystem. You'll be one of the engineers shaping what that surface looks like for the next several years
• Design, ship, and own public-facing APIs and backend services in Go -from technical proposal & design docs through implementation, testing, and production rollout and on-call support
• Use AI coding agents as part of your daily workflow
• Partner with frontend engineers, product managers, and security researchers to ship the customer experience end-to-end
• Take ambiguous or broadly-scoped problems and turn them into well-defined technical plans that the team can execute on
• Author design and architectural documents and use them to drive alignment across engineering and product teams
• Collaborate with internal platform teams, product managers, and stakeholders across the organization to understand their needs and deliver impactful solutions
• Consider stability, performance, and scalability in your designs and in the guidance you provide to the team
• Mentor and grow other engineers on the team through code review, pairing, and technical leadership
• Participate in an on-call rotation

The application process

• Anticipated Posting Close Date*: 10/24/2026
• A fully completed application and resume or CV are required when applying

Benefits

• Parental support and beyond: We support our families by offering generous time off for parental leave. And beyond that, we work hard to build a culture that allows for all employees to have the life outside work that they desire year round.
• Health and wellness: Your well-being matters here. Our health plans offer a variety of options, including full medical, dental, and vision coverage, short- and long-term disability insurance, mental health resources, and more.
• Invest in your future: We offer 401(k)/retirement plans, employee stock purchasing plans (ESPP), and reimbursements for learning and development programs — so we can support your ongoing growth and success.
• Keep learning and growing: Helping people go further means nurturing their talent. Through annual reimbursements for employee learning activities, regular hangouts and advice from our Senior Staff, talks from industry leaders, and cultural events — we offer tons of opportunities for people to learn. And we’re always looking to grow as a company, too: we collect employee engagement and experience data annually and leverage our Employee Experience Champion Network to understand employee feedback, so we can keep improving.