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CoStar Group

Senior Front-End Engineer - OnTheMarket Technology, London

Sorry, this job was removed at 02:12 p.m. (GMT) on Tuesday, Dec 09, 2025
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London, Greater London, England, GBR
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London, Greater London, England, GBR

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Senior Front-End Engineer - OnTheMarket Technology, London


Job Description


COSTAR GROUP - SENIOR FRONT-END ENGINEER – ONTHEMARKET TECHNOLOGY – LONDON

OVERVIEW

CoStar Group (NASDAQ: CSGP) is a leading global provider of commercial and residential real estate information, analytics, and online marketplaces.  Included in the S&P 500 Index and the NASDAQ 100, CoStar Group is on a mission to digitize the world’s real estate, empowering all people to discover properties, insights and connections that improve their businesses and lives. 

We have been living and breathing the world of real estate information and online marketplaces for over 35 years, giving us the perspective to create truly unique and valuable offerings to our customers.  We’ve continually refined, transformed and perfected our approach to our business, creating a language that has become standard in our industry, for our customers, and even our competitors.  We continue that effort today and are always working to improve and drive innovation.  This is how we deliver for our customers, our employees, and investors.  By equipping the brightest minds with the best resources available, we provide an invaluable edge in real estate. 

In December 2023 CoStar Group purchased OnTheMarket (OTM) with the intention of developing this established brand into the UK's number 1 Residential Property portal. Supported by the deep expertise of the CoStar Group and our Homes and Apartments teams, we will develop a world class user experience through offering the very best written content, imagery, design and functionality. The OnTheMarket product will support home buyers, sellers, and agents better than ever!

Learn more about OnTheMarket.

ROLE DESCRIPTION

The role of Senior Front-end Engineer will be a pivotal role within the OTM UX team, reporting to the Director, Residential Technology. The UX team is responsible for the user interface, user experience, and overall performance of the OnTheMarket web apps and iOS / Android apps. This role will be instrumental in delivering a seamless and engaging experience for our users.

This role would be suited to an individual with a deep understanding of React, Redux, and Next.js. The candidate must be able to demonstrate expertise in building scalable and maintainable user interfaces, ensuring high performance and responsiveness across all devices. A strong ability to translate designs and user requirements into high-quality, reusable and maintainable code.

RESPONSIBILITIES

  • Develop and maintain user-facing features using React, Redux and Next.js.

  • Build reusable components and front-end libraries.

  • Optimise applications for maximum speed and scalability.

  • Working with the CTO Collaborate with the Head of UX to ensure the technical feasibility of their designs.

  • JS application reliability including; incident management, performance tuning, monitoring & deployment.

  • Full workflow with testing frontend applications (unit, integration, or E2E) and advanced Git version control.

QUALIFICATIONS

  • Bachelor’s degree in Computer Science, Mathematics, Engineering or equivalent experience

  • Strong 4+ years commercial experience with JavaScript (ES6/ES7+)

  • Commercial experience with React and Redux.

  • Proficient with React features such as hooks, pure components, error handling, HOCs, and lazy loading and hands-on experience with Next.js and Server-Side Rendering (SSR)

  • Experience integrating and working with APIs, including the fetch() API

  • Solid understanding of HTTP, semantic HTML, accessibility, and responsive web design across various browsers and devices

  • Strong CSS skills, including Tailwind, Flexbox, Grid, and modern web layout techniques

  • Performance-minded, with experience optimizing rendering, load times, and tracking key metrics like Core Web Vitals using tools such as Lighthouse

  • A good grasp of software design principles

NICE TO HAVE

  • A good eye for design and attention to UI/UX details

  • Familiarity with CI/CD pipelines, particularly Jenkins

  • Experience in applying general SEO concepts

  • Experience with AWS is a plus

  • Experience working with the Google Maps API, data visualisations and creating clean, simple and compatible email templates

  • Familiarity with TypeScript

WHAT’S IN IT FOR YOU?
Working at CoStar Group means you'll enjoy a culture of collaboration and innovation that attracts the best and brightest across a broad range of disciplines. As well as having an outstanding working environment based in London Blue Fin. Other perks include full private medical cover, dental cover, Life Assurance and member rewards, 28 days annual leave, a competitive pension, season ticket loans, enhanced maternity and paternity pay and much more!

At CoStar, we recognise the positive value of diversity and promote equality. We aim at all times to recruit the person who is most suited to the job and welcome applications from people of all backgrounds – men and women, people of all ages, sexual orientations, nationalities, religions and beliefs. However, we particularly encourage applications from women, disabled and Black, Asian and Minority Ethnic (BAME) candidates, as these groups are underrepresented throughout the commercial real estate industry.>

CoStar Group is an Equal Employment Opportunity Employer; we maintain a drug-free workplace and perform pre-employment substance abuse testing.


CoStar Group is an Equal Employment Opportunity Employer; we maintain a drug-free workplace and perform pre-employment substance abuse testing

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