Lead C++ Engineer - London | what3words

London United Kingdom

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The what3words team is on a mission to create the global standard for communicating location. We’re making the world an easier, more efficient and safer place for everyone.

what3words is built on the very latest tech platforms, which we’re always innovating and improving on – from a new website to apps, car and logistics software and hardware, voice technology, OCR and more.

We're looking for an outstanding C++ developer. A large part of your role will be to build our OCR technologies, based on Tesseract. These allow our users to "scan" three words using your phone. You will be responsible for both maintenance and R&D work in OCR, refining our algorithm to improve our recognition accuracy, which will require creative algorithmic problem solving. Experience in the application of machine learning to real-world problems is highly desirable. We take a data-driven approach, with thousands of labelled sample videos which provide us with a data set to test against. You will need a keen awareness of code performance, and have a strong mathematical background. Experience in OCR itself is not required, but is desirable.

We are proud of our tech stack and you will also be exposed to technologies such as ReactJS, Docker, Redis, AWS Lambdas, Prometheus, Grafana, Python, Athena, BigQuery, Java, Scala, and Swift. At the very heart of all our tech is our core C++ SDK, which converts to/from 3 words and powers our autosuggest and voice functionality.

Life on the what3words tech team is innovative, Agile and fast-paced. You’ll be joining a group of talented people from all over the world on an unprecedented journey.

Everyday brings new challenges, and we are continually learning.

We are a global company located in West London’s creative hub. Our headquarters are near Portobello Road and a short walk from Westbourne Park and Royal Oak tube stations.


  • C++11 (advanced)
  • Git
  • CMake
  • Strong mathematical background

Desirable Skills:

  • Cross-platform compilation
  • Machine learning experience
  • Image processing experience
  • OCR experience
  • Boost
  • Voice recognition experience
  • OpenCV

You will have:

  • Excellent communication skills with perfect spoken and written English
  • The ability to talk to techies and non-techies in suitable language
  • A passion for development and staying current with technology trends
  • The ability to work both independently and with others
  • A focus on high quality software engineering work and attention to detail
  • The ability to work in a fast-paced, deadline-driven environment

Extra credit if you:

  • Like maps and location based services and know what a GIS is, what Leaflet and the Google Maps API are and what the difference between latitude and longitude is
  • Are able to understand the business context of what you’re doing – understand the value your work creates.
  • Enjoy learning new skills in scripting languages and how to use those to showcase our products

**Tier 2 sponsorship available for candidates requiring a UK work visa**


Salary: Competitive

25 days holiday

Share options


Private healthcare

Cycle to work

VDU eye tests


Free breakfast & snacks

Birthday vouchers

Weekly lunch & learn sessions

Regular team lunches & team socials

Sports and hobbies clubs

open chat