Software Engineer

London, United Kingdom

We realise people do not fit into neat boxes. We are looking for people who are curious and committed to developing themselves and learning new skills, and we are ready to help you to do that. Cloudflare’s mission is to build a better internet. We cannot do this 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. We do not discriminate against employees on the basis of any characteristic or classification protected by law.

About Us

At Cloudflare, we have our eyes set on an ambitious goal: to help build a better Internet. Today, Cloudflare runs one of the world’s largest distributed networks that powers more than 1.5 trillion page views each month across 8 million Internet properties. Cloudflare protects and accelerates any Internet application online without adding hardware, installing software, or changing a line of code.

Our customers range from Fortune 500 companies and nonprofits to small businesses and budding entrepreneurs. We are working to create a faster, more secure, and more reliable experience for anyone online and given the scale at which we operate, our mission is big. Our team is hard at work shaping the future of the Internet by solving some of its toughest challenges. Come join us.


You will work as part of our core engineering team in London which builds the Cloudflare system running in 150+ cities around the world. Your code will impact upwards of 2.8 billion people/month, as well over 10% of all internet connections which pass through our servers. 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 that handles over 10% of internet connections, 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.

If you joined the Edge team, for example, your first 6 months could look like this: After a structured onboarding you buddy with a fellow 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 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.

If you have a preference for any of these teams, please note it in your application.

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
  • Understand how the internet works at a protocol level
  • Good unix knowledge, patches to Operating Systems a huge plus for some roles
  • Understanding of security issues and responsibilities
  • Experience of debugging and testing
  • Analysing data sets such as logs
  • Designing and building APIs

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 Us 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. In 2014, we launched Project Galileo, an initiative through which we partner with global NGOs to identify websites at risk of attack and provide the same state-of-the-art mitigation technology already used by Cloudflare’s enterprise customers - at no cost. Project Galileo equips politically and artistically important organizations and journalists with powerful tools to defend themselves against attacks that would otherwise censor their work.

Additionally, in 2016, we announced our partnership with Path Forward, a nonprofit organization that works with companies to create 18-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. With the lofty goal of shaping the future of the Internet, we’re focused on recruiting the best and the brightest, no matter what.


We’re passionate about connecting highly skilled women with leading companies commited to diversity and inclusion

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