How to Build a Url Shorter with C# Minimal APIs and Azure

The post outlines a simple URL shortener built with C# minimal APIs and Azure resources. It keeps the first version small, with 301 redirects, a home page, a custom 404 page, and low-cost hosting on Azure.

Reading notes

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• The redirect lookup uses Azure Table Storage because it is described as one of the cheapest and quickest storage options in Azure.
• The code uses DefaultAzureCredential instead of a connection string, so it can authenticate locally with Azure CLI and in Azure with a system-assigned managed identity.
• A storage account with a table named UrlLookup is required, and the StorageUri setting must point to that table endpoint.
• The account needs Storage Table Data Reader permission, because contributor or owner roles are not enough to read table values.
• New links are added as table entries with partition key url, row key set to the token, and a TargetUrl property for the destination.
• The minimal API route captures any path token with MapGet("/{id}") and queries the table for a matching row.
• If no row is found, the code returns a 404 status and serves a custom 404.html file from the web root.
• UseDefaultFiles and UseStaticFiles serve index.html from wwwroot as the home page.
• The complete example combines redirects, the static home page, and the custom 404 page in one minimal API app.
• The post suggests future additions such as a secure page to manage URLs and output caching to reduce costs.
• For random short codes, it points to the hashids libraries.
• The hosting example uses Azure Container Apps with continuous deployment from GitHub and Azure Container Registry.
• The app needs a StorageUri environment variable in Container Apps.
• Azure Container Apps do not currently support free managed SSL certificates, so the post links to a Let’s Encrypt workaround.
• To let the Container App access storage, the system-assigned managed identity must be granted Storage Table Data Reader on the storage account.