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Backend / Systems Engineer

Engineering Full-time

Go, DNS, TLS, and the edge proxy under load

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This is the systems seat. You will work in Go on the parts of the product that have to be correct and fast: the edge proxy that terminates TLS and reverse-proxies customer traffic, the on-demand certificate issuance that happens inside the handshake, and the DNS and verification services that decide whether a domain is really ready. When a connection is slow or a certificate fails to issue, you are the person who finds out why.

What you will do

  • Own the reverse-proxy edge: TLS termination, request routing, connection handling, and the latency and reliability budgets that go with serving other companies' traffic.
  • Build on-demand TLS so certificates are issued and renewed inside the handshake through ACME, with no manual step for the end-user.
  • Work on the DNS layer: querying provider state, confirming records propagated, and handling apex domains and the awkward cases providers create.
  • Run drift monitoring that catches a record that changed or a certificate about to lapse, and fire the webhook before the customer notices.
  • Set up the observability, load testing, and alerting that let a small team trust the edge in production.

What we are looking for

  • You are fluent in Go and have built networked services that stay up under real traffic.
  • You know TLS, certificates, and ACME well enough to debug a failed handshake or a renewal that did not fire.
  • You understand DNS beyond the basics: propagation, caching, apex versus subdomain, CNAME and ALIAS behavior across providers.
  • You have run a proxy, load balancer, or edge service in production and have opinions about timeouts, retries, and backpressure.

Bonus

  • You have implemented an ACME client or worked directly with a certificate authority's issuance flow.
  • You have operated infrastructure that terminates TLS for domains you do not own.
  • You have profiled and cut tail latency in a Go service.

Where we stand

Equal opportunity employer

We hire on merit and welcome everyone.

Reasonable accommodations

Available for disability and pregnancy, on request.

Participates in E-Verify

We confirm work authorization only after you accept an offer.

No salary history asked

We never ask what you earned before.

Your data, protected

Applicant privacy notice covering GDPR and CCPA.

Custom Domain is an equal opportunity employer. We do not discriminate in hiring or employment on the basis of race, color, religion, sex (including pregnancy, sexual orientation, and gender identity), national origin, age, disability, genetic information, or any other characteristic protected by applicable federal, state, or local law. All employment decisions are based on qualifications, merit, and business need.

Custom Domain participates in E-Verify. We provide the U.S. Department of Homeland Security and the Social Security Administration with information from each new employee's Form I-9 to confirm authorization to work in the United States. We use E-Verify only after you have accepted a job offer and completed Form I-9.

If you need a reasonable accommodation to take part in the application or interview process, write to accommodations@customdomain.ai. We will work with you on accommodations for qualified individuals with disabilities and for known limitations related to pregnancy, childbirth, or related medical conditions.

Applicants have rights under federal employment laws. See the EEOC Know Your Rights notice, and review our Applicant Privacy Notice. We do not ask for your salary history.