Back End Developer Jobs in Boulder, CO (NOW HIRING)

Fastly helps people stay better connected with the things they love. Fastly's 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. Fastly's customers include many of the world's most prominent companies, including GitHub, Yelp, Paramount, and JetBlue.
We're building a more trustworthy Internet. Come join us.
Posting Open Date: June 24, 2026
Anticipated Posting Close Date*: July 10, 2026
*Job posting may close early due to the volume of applicants.
Senior Backend Software Engineer (APIs), Security Products
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.
What You'll Do:

• 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 the understand 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

What We're Looking For:

• 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

We'll be super impressed if you have experience in any of these:

• Built or operated security products (WAF, bot, DDoS, app security).
• Working knowledge of auth at API scale (RBAC, OAuth, JWT, SAML)

Work Hours:

• 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

Work Location(s) & Travel Requirements:
This position is open to the following preferred office locations:

• San Francisco, CA, USA
• Denver, CO, USA

Fastly currently embraces a largely hybrid model for most roles which allows employees flexibility to split their time between the office and home.
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 - $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.
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 initiatives. Outside 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 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.
All job applications must be submitted through our official careers site at www.fastly.com/about/careers. 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 @fastly.com or @recruiting.fastly.com 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 candidateaccommodations@fastly.com or 501-287-4901.
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