connection-string-builder
Build a SQL Server connection string field by field, or paste an existing one to see it broken down. Runs entirely in your browser.
Fill in the fields on the left, then click "Build string".
// things this catches
Encrypt not set for Azure SQL. Azure SQL rejects unencrypted connections outright — if your server host contains database.windows.net and Encrypt is off, that's almost always a bug, not a choice.
TrustServerCertificate=True in what looks like a production host. It's the right call for a local Docker SQL instance with a self-signed cert; it's a silent security hole if it ships to prod by accident.
Both Integrated Security and a User Id set. These are mutually exclusive — the driver will ignore one, and it's rarely obvious which.
Since .NET 6, Microsoft.Data.SqlClient defaults Encrypt to True and TrustServerCertificate to False — a connection string that worked under .NET Framework's older client can suddenly fail after a migration purely because of this default flip. Worth checking explicitly rather than assuming the old string still behaves the same way after upgrading.
// why "just paste it from Azure Portal" isn't always enough
The Azure Portal's connection string blade gives you a string that's syntactically correct but not always what you want to run with — it typically enables Encrypt but leaves the auth block as a placeholder, and it won't reflect an Azure AD identity setup even if that's actually how your app authenticates in production. Treat it as a starting template, not the final string.
// learn more
For annotated examples covering Windows auth, Azure AD, and connection pooling, see SQL Server Connection String Examples. Building the API that sits in front of this database next? The cURL Converter turns a copied curl command into working request code in the same languages this site already covers.
A few mistakes show up constantly in .NET connection strings, so the builder flags them as you go rather than letting you find out at runtime.