Oded Coster, Developer in London, United Kingdom
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Oded Coster

Verified Expert  in Engineering

Back-end Developer

London, United Kingdom
Toptal Member Since
June 23, 2021

Oded is a highly accomplished architect and software engineer with 25 years of experience in the field. He has worked for world-known names such as Tesco, ASOS, AKQA, and Stack Overflow. Oded also ran his own consultancy in London for nearly a decade. He is one of the top contributors at Stack Overflow, with over 7,500 programming answers reaching over 60 million people. Oded enjoys freelancing and the opportunity to work with different companies and projects.


Intelligent Hack
.NET Core, C#, .NET, Microsoft SQL Server, Redis, Leadership, Code Architecture...
C#, .NET Core, Microsoft SQL Server, TypeScript, JavaScript, Code Architecture...
Stack Overflow
C#, .NET, Microsoft SQL Server, Website Performance, Database Performance...




Preferred Environment

Windows, Visual Studio, .NET Core, Vanilla JS, Simplicity

The most amazing...

...performance work I've done was at Stack Overflow, a site that serves over 40 million pages a day using only nine web servers and a single database server.

Work Experience

CTO & Senior Consultant

2020 - PRESENT
Intelligent Hack
  • Helped reduce technical debt in the 20-year-old codebase of a client by, among others, cleaning up millions of lines of unused and redundant code.
  • Brought in a culture of engineering excellence and helped client employees to feel empowered and gain a sense of ownership of their codebase.
  • Restructured a large Visual Studio solution to enable large-scale refactoring, like reducing the number of projects used by over 170.
Technologies: .NET Core, C#, .NET, Microsoft SQL Server, Redis, Leadership, Code Architecture, Simplicity, Database Performance, SQL Performance, Website Performance, Observation, Monitoring, Azure, Azure DevOps, Visual Studio, Visual Studio Code (VS Code), LINQ, Team Effectiveness, Team Leadership, Windows PowerShell, Performance Engineering

Senior Software Engineer

2018 - 2019
  • Wrote a code generator that produced JavaScript, TypeScript, and Solidity code based on a JSON description file. This was needed to ensure the product front end and the Ethereum blockchain were packing and unpacking transferred data in the same way.
  • Migrated many database fields to use less storage, as initially, they were using varchar fields to hold what was essentially binary data. This translated to very large space savings and more database transactions per second.
  • Implemented consumption of WebSocket subscriptions to replace direct polling of Ethereum nodes.
Technologies: C#, .NET Core, Microsoft SQL Server, TypeScript, JavaScript, Code Architecture, Simplicity, ASP.NET MVC, Amazon Web Services (AWS), Visual Studio, Windows PowerShell

Senior Software Engineer

2013 - 2018
Stack Overflow
  • Revamped the user profile, including inline reputation graphs and the introduction of user metric such as the social impact of a user on the community.
  • Wrote the export scripts still used for the quarterly data dumps that Stack Overflow produces (questions and answers, comments, and other public data). This is a highly efficient process that dumps many terabytes of data into files in hours.
  • Implemented a header redesign that was launched on over 300 sites and brought much-needed cohesion to the Stack Exchange network of sites.
Technologies: C#, .NET, Microsoft SQL Server, Website Performance, Database Performance, Performance Engineering, HTML, CSS, JavaScript, Redis, HAProxy, Simplicity, Visual Studio, Windows PowerShell, SQL Performance

Founder and Consultant

2005 - 2013
  • Wrote an automated image resizing application based on highly specific parameters and workflow, estimated to save £90,000 per year. Client: ASOS.
  • Designed and wrote a dynamic website generator and deployer. This included website creation and deployment, database creation, public DNS updates, and hooking up the systems. This work saved many person-hours every month. Client: Liquid Thinking.
  • Helped Tesco revamp and modernize their groceries website. At the time, they had the largest retail site in the world.
Technologies: C#, .NET, Microsoft SQL Server, HTML, CSS, JavaScript, Code Architecture, Leadership

Senior Software Engineer

2001 - 2004
  • Designed and wrote a custom content management system for the commerce site, allowing the marketing department to create custom web pages without developer intervention.
  • Wrote a sophisticated customer segmentation tool, allowing the marketing department to target highly specific segments of the user base.
  • Implemented an issues and bug tracking system for internal IT usage.
Technologies: ASP.NET, Microsoft SQL Server, HTML, JavaScript, CSS

Stack Overflow

Stack Overflow is a Q&A site for programmers. It is the number one destination for any programmer who is stuck and needs answers and is in the top 40 most used sites in the world.

I spent five years working in the core team at Stack Overflow - working on the Q&A engine and performance and features on the site.

Automated Image Resizing

For ASOS, I wrote an automated image resizing application based on their proprietary image editor workflow. This included live previews and curated sets of pre-selected editing options.

This work was estimated to save £90,000 per year in increased image editor productivity.

Christmas Campaign - Composited Video

I developed all video and audio processing routines for the Halifax Save the Children Christmas choir campaign.

This web app allowed customers of the bank to record themselves singing Christmas carols, then select other friends and customers that have also recorded themselves.

The application then composited these videos and audio streams to produce a single video where the selected people were singing together.

Three Languages Code Generator

I designed and wrote a code generator that produced JavaScript, TypeScript, and Solidity code based on a JSON description file.

This was needed to ensure the product front end and the Ethereum blockchain were packing and unpacking transferred data in the same way.

The code generator was a cornerstone in getting third-party game creators onto the FunFair platform.
2008 - 2012

Diploma in Computer Science

Open University - England


FFmpeg, LINQ


Visual Studio


.NET Core, .NET, ASP.NET MVC, ASP.NET, Vanilla JS, Windows PowerShell


Databases, SQL Performance, Microsoft SQL Server, Database Performance, Redis


C#, HTML, JavaScript, TypeScript, CSS


Windows, Azure, Visual Studio Code (VS Code), Amazon Web Services (AWS)


DevOps, Azure DevOps


Software Engineering, Website Performance, Back-end, Performance Engineering, Simplicity, Teamwork, Front-end, HAProxy, Leadership, Code Architecture, Observation, Monitoring, Team Effectiveness, Team Leadership

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