AI-Assisted Site Rebuild

This case study is the website you are reading. In October 2026, all that remained of our previous ASP.NET Core site was its compiled, deployed files. There was no source code to work from: the controllers, services and page templates existed only inside compiled assemblies.

We approached it as a modernisation project and carried it out with an AI coding agent, Claude Code. Our technical architect set the direction, approved the design decisions and reviewed the results, while the AI handled much of the hands-on work.

Recovering the code

• We decompiled the application with ILSpy, recovering ten controllers, an email service and the view models.
• The eighteen Razor page templates had been compiled into the application, so a small purpose-built converter turned them back into editable .cshtml files.
• We copied across the static content, leaving out files the build now generates itself.

Rebuilding on .NET 10

• A clean .NET 10 solution following current conventions, including minimal hosting and nullable reference types.
• The outdated WebClient replaced with HttpClient, and email sending moved into its own service.
• Unused dependencies removed, and the mail library updated to resolve known security advisories.
• Hard-coded server paths made configurable, and a Web Deploy publish profile added.

Checking the result

Rather than take the new code on trust, we ran the old and new sites side by side and compared the HTML of every page. Apart from one page that depends on an external feed, every page matched the original exactly. The interactive features were then tested end to end before the site went live.

Improvements along the way

• Credentials moved out of the configuration files.
• Error details and source paths no longer shown to visitors.
• The live site no longer runs in development mode.
• Input validation added to the Footy Doodle image service.
• The Footy Doodle 3D football made interactive (drag to spin, flick, pinch or scroll to zoom, plus keyboard controls), with automated browser tests for mouse, touch and keyboard.
• Cache-busting added, so updates reach visitors straight away through the CDN.

The outcome

The recovery, rebuild, checks and first deployment were all completed in a single day. AI made the building fast, and careful design and thorough testing made it safe to put live.

Technologies used:

• Claude Code
• .NET 10
• ASP.NET Core MVC
• C#
• Razor
• ILSpy
• MailKit
• three.js
• Puppeteer
• Web Deploy
• Cloudflare

Questions and answers

Can AI rebuild a website when the source code has been lost?

Yes, with experienced people directing it. We decompiled the old site with ILSpy, and the AI wrote a converter that turned the compiled page templates back into editable Razor files. It handled much of the hands-on work while we set the direction and checked the results.

How long did the website rebuild take?

One day. The recovery, the rebuild on .NET 10, the page-by-page checks and the first deployment were all completed on 13 October 2026.

How was the rebuilt site checked against the original?

We ran the old and new sites side by side and compared the HTML of every page. All of them matched exactly, apart from one page that relies on an external feed. Interactive features were then tested in a browser, including automated tests for mouse, touch and keyboard.

Which parts of the rebuild did the AI carry out?

Claude Code, the AI coding agent, carried out most of the hands-on work: decompiling, writing the converter, rebuilding the code and running the tests. Our technical architect set the direction, approved the design decisions and decided what went live.

What improved beyond a like-for-like copy?

Passwords were moved out of the configuration files, error details are no longer shown to visitors, the live site no longer runs in development mode, input is validated, and libraries with known security issues were updated. The Footy Doodle football also became fully interactive.

What technology stack did the rebuild use?

.NET 10 and ASP.NET Core MVC with C# and Razor, ILSpy for decompiling, MailKit for email, three.js for the football, Puppeteer for browser testing, Web Deploy for publishing and Cloudflare in front of the site.