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Software Engineer
Premium Job From Cloudfare
Recruiter: Cloudfare
Listed on: 23rd August
Location: London
Salary Notes: Competitive + Benefits
Type: Permanent
Start Date: ASAP
Reference: CLFD441
Contact Name: Cloudfare

Software Engineer 

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 world's largest networks that powers trillions of requests per month. Cloudflare protects and 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 and a decrease in spam and other attacks. Cloudflare was recognized by the World Economic Forum as a Technology Pioneer and named to Entrepreneur Magazine's Top Company Cultures list.

We realize people do not fit into neat boxes. We are looking for curious and empathetic individuals who are committed to developing themselves and learning new skills, and we are ready to help you do that. We cannot complete our mission without building a diverse and inclusive team. We hire the best people based on an evaluation of their potential and 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 and 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, and 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 and secure as possible. Filtering malicious traffic and handling good traffic according to customers configuration. Projects include implementing QUIC, bot mitigation and content optimisation.


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


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


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


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


Improving and 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 and supporting the operation of a vital core platform.  

The current platform makes extensive use of Nginx/C and Lua, and we're 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 and 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 and robust as changes are made. You obsess about service resilience and work with our support engineers to help them to debug and fix customer issues in these areas. You use our performance tooling to identify areas where the system is not fast enough, and 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, and make contact with engineers on other teams who have exciting ideas about a way to take the work further.

Examples of desirable skills and experience

We do not require you to have all of these!

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

It is also desirable that you have skills and experience in the following areas but it's 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++, and Python, but are looking for good engineers regardless of language.

A degree is not required for this position.

What Makes Cloudflare Special?

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

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

Project Athenian: We created Athenian Project to ensure that state and local governments have the highest level of protection and reliability for free, so that their constituents have access to election information and 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 and privacy-centric public DNS resolver. This is available publicly for everyone to use - it is the first consumer-focused service Cloudflare has ever released. Here's the deal - we don't store client IP addresses never, ever. We will continue to abide by our privacy policy and ensure that no user data is sold to advertisers or used to target consumers.

Sound like something you'd like to be a part of? We'd 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 and place great value in both diversity and 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.

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