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CloudFlare // highly-available global networks
Engineering, Full Time    London, UK    Posted: Wednesday, June 12, 2019
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About Us

At Cloudflare, we have our eyes set on an ambitious goal: to help build a better Internet. Today the company runs one of the worlds largest networks that powers more than 10 trillion requests per month. Cloudflare protects & accelerates any Internet application online without adding hardware, installing software, or changing a line of code. Internet properties powered by Cloudflare have all web traffic routed through its intelligent global network, which gets smarter with every request. As a result, they see significant improvement in performance & a decrease in spam & other attacks. Cloudflare was recognized by the World Economic Forum as a Technology Pioneer & named to Entrepreneur Magazines Top Company Cultures list.

We realize people do not fit into neat boxes. We are looking for curious & empathetic individuals who are committed to developing themselves & learning new skills, & we are ready to help you do that. We cannot complete our mission without building a diverse & inclusive team. We hire the best people based on an evaluation of their potential & support them throughout their time at Cloudflare. Come join us!

What you'll do

You will work as part of our core engineering team in London which builds the Cloudflare system running in 160+ cities around the world. Your code will impact upwards of 2.8 billion people/month. Your work will focus on building robust, secure & high performance distributed systems. We are a small engineering team operating at massive scale, so what you do will have huge influence.

We work in agile teams, so you will be supported by colleagues, & collaborate with other teams around the company. Our London teams include:


Building a TLS/HTTP proxy, to make the connection from eyeball to edge as fast & secure as possible. Filtering malicious traffic & handling good traffic according to customers configuration. Projects include implementing QUIC, bot mitigation & content optimisation.


Building Go APIs & React UIs to support feature configuration, & to retrieve data from the edge to provide analytics & insight APIs for those features.


Crafting, building, & scaling one of the biggest global data pipelines to overcome network delays & partitions. Using Go, Kafka, ClickHouse, Flink & PostgreSQL to store & analyse in excess of 10 million events per second (and growing fast).


Maintaining our Authoritative DNS server & our public resolver We like to be state of the art & roll out new standards features early like DNS-over-TLS.


Using core networking to stop DDoS at kernel or switch level. Creating detection & control systems for automatic reaction to attacks by analysing a large volume of real-time data. Managing & routing traffic at layer 4 to optimise our performance.


Improving & operating our built-in house distributed key-value store. It stores over 600 million key-value pairs distributed over 50,000 Unix processes. Quicksilver is being accessed each time a request hits Cloudflare Edge. Quicksilver serves over 11 million request a second for a daily total exceeding 1 trillion.

This particular role is on one of our main Edge teams. The team is responsible for developing & supporting the operation of a vital core platform.

The current platform makes extensive use of Nginx/C & Lua, & were currently planning how to evolve the platform. At the moment we are investigating Rust as a candidate technology for future iterations of the platform. Initially you will be working on the existing Nginx/C & Lua codebase.

We are interested in people who have experience being part of a team that develops & supports services, as well as experience with the technologies that we use. Having experience of writing production Rust code is a bonus, but is not essential, although a desire to work with Rust is welcomed due to increasing use of Rust within Cloudflare. This role will mean that you will initially be working on the existing code base, as well as being part of the team as it looks to the future.

Experience of identifying performance issues, or performance optimisation, is also a bonus. Having experience of working within enterprise SLA targets is strongly desirable.

Your first 6 months could look like this: After a structured onboarding you buddy with a more experienced engineer to learn to code at our edge in Lua. You take ownership of a few feature areas, making sure they are well documented & robust as changes are made. You obsess about service resilience & work with our support engineers to help them to debug & fix customer issues in these areas. You use our performance tooling to identify areas where the system is not fast enough, & start doing some lower level C/C++/Go or Rust (again, working with others) to build a new module to speed it up. You talk about this work at one of our weekly company talks, put together a post for the company blog, & make contact with engineers on other teams who have exciting ideas about a way to take the work further.

Examples of desirable skills & experience

We do not require you to have all of these!

  • Desire to learn & improve
  • Understanding of distributed systems
  • Talking about your work to technical & non technical people
  • Working as part of an agile software development team
  • Understanding of security issues & responsibilities
  • Experience of debugging & testing
  • Analysing data sets such as logs
  • Designing & building APIs

It is also desirable that you have skills & experience in the following areas but its ok to demonstrate a willingness/desire to learn them.

  • Understand how the Internet works, at a protocol level
  • Good knowledge of unix-like systems

We work with languages such as Lua, Go, Rust, C, C++, & Python, but are looking for good engineers regardless of language.

A degree is not required for this position.

What Makes Cloudflare Special?

Were not just a highly ambitious, large-scale technology company. Were a highly ambitious, large-scale technology company with a soul. Fundamental to our mission to help build a better Internet is protecting the free & open Internet.

Project Galileo: We equip politically & artistically important organizations & journalists with powerful tools to defend themselves against attacks that would otherwise censor their work, technology already used by Cloudflares enterprise customers--at no cost.

Project Athenian: We created Athenian Project to ensure that state & local governments have the highest level of protection & reliability for free, so that their constituents have access to election information & voter registration.

Path Forward Partnership: Since 2016, we have partnered with Path Forward, a nonprofit organization, to create 16-week positions for mid-career professionals who want to get back to the workplace after taking time off to care for a child, parent, or loved one. We released to help fix the foundation of the Internet by building a faster, more secure & privacy-centric public DNS resolver. This is available publicly for everyone to use - it is the first consumer-focused service Cloudflare has ever released. Heres the deal - we dont store client IP addresses never, ever. We will continue to abide by our privacy policy & ensure that no user data is sold to advertisers or used to target consumers.

Sound like something youd like to be a part of? Wed love to hear from you!

Cloudflare is proud to be an equal opportunity employer. We are committed to providing equal employment opportunity for all people & place great value in both diversity & inclusiveness. All qualified applicants will be considered for employment without regard to their, or any other person's, perceived or actual race, color, religion, sex, gender, gender identity, gender expression, sexual orientation, national origin, ancestry, citizenship, age, physical or mental disability, medical condition, family care status, or any other basis protected by law. We are an AA/Veterans/Disabled Employer.

Cloudflare provides reasonable accommodations to qualified individuals with disabilities. Please tell us if you require a reasonable accommodation to apply for a job. Examples of reasonable accommodations include, but are not limited to, changing the application process, providing documents in an alternate format, using a sign language interpreter, or using specialized equipment. If you require a reasonable accommodation to apply for a job, please contact us via e-mail at or via mail at 101 Townsend St. San Francisco, CA 94107.

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