Dev Tunnels: Test Webhooks and Share Local Apps Without a Deploy

If you read the Cloudflare Tunnel post, you know the problem: localhost does not accept webhooks, OAuth providers reject http://localhost as a redirect URI, and showing a client a work-in-progress means a deploy. Cloudflare Tunnel solves it, but it wants a Cloudflare account and domain setup.

Microsoft Dev Tunnels is the zero-setup alternative. It is already installed if you have Visual Studio 2022 17.4+ (including VS 2026) or the Azure CLI. One command, and your localhost has a persistent public URL backed by Azure infrastructure.

When to use which:

• Cloudflare Tunnel: you own a domain and want a stable named URL (api.yourdomain.com), production-ish setup.
• Dev Tunnels: you want to be running in 30 seconds, no domain, already have VS or the Azure CLI.

How it works

The devtunnel process opens an outbound connection to Azure’s relay. No inbound ports, no firewall changes. Traffic hits the public *.devtunnels.ms URL and forwards to your local port.

graph LR
    A[Webhook / OAuth Provider\nExternal Client] -->|HTTPS| B[Azure Dev Tunnels\nEdge *.devtunnels.ms]
    B -->|Persistent connection| C[devtunnel CLI\nor Visual Studio]
    C -->|localhost| D[Your .NET App\nlocalhost:5217]

    style A fill:#f4a261,stroke:#e76f51,color:#000
    style B fill:#0078d4,stroke:#005a9e,color:#fff
    style C fill:#0e7490,stroke:#155e75,color:#fff
    style D fill:#16a34a,stroke:#15803d,color:#fff

Expose localhost in three commands

devtunnel user login              # one-time, uses your Azure/Microsoft account
devtunnel host -p 5217            # host a tunnel for localhost:5217
# Connect: https://abc123-5217.devtunnels.ms
# Inspect: https://abc123-5217-inspect.devtunnels.ms

That URL is live immediately.

The main use case: webhooks

Your app needs a POST from Stripe, GitHub, or Azure Event Grid, and none of them can reach localhost. Run your API, then host the port with devtunnel host -p 5217 --allow-anonymous and point the provider’s webhook at https://abc123-5217.devtunnels.ms/webhooks/stripe. The --allow-anonymous flag skips the tunnel’s built-in login page, which a webhook sender cannot pass. The -inspect URL gives you a request/response viewer, like ngrok’s dashboard, so you can see the exact payload before your handler runs.

The same tunnel covers the other localhost chores:

• OAuth redirect URIs: register https://<id>.devtunnels.ms/signin-oidc in your app registration. Azure AD, GitHub, and Google accept it where they reject localhost.
• Stable URLs: the quick-start URL rotates each session. devtunnel create <name> plus devtunnel port create <name> -p 5217 gives you a named tunnel that keeps the same URL, so you register a callback once.
• Client demos: devtunnel host -p 4200 and send the link, no deploy. First-time visitors see a confirmation page unless you add --allow-anonymous.
• Visual Studio: the same thing lives on the debug toolbar (Dev Tunnels, then Create a Tunnel), and the URL is exposed as VS_TUNNEL_URL during the session.

Dev Tunnels vs Cloudflare Tunnel vs ngrok

Gotchas

• Session auth page: by default a tunnel visitor sees a Microsoft login prompt. Add --allow-anonymous for webhooks and public demos.
• Tunnel lifetime: temporary tunnels close with the CLI; named tunnels persist but still need devtunnel host running.
• Rate limits: Dev Tunnels has usage limits. It is a dev tool, not a way to run production traffic through a tunnel.
• VS and CLI are separate: a tunnel created in Visual Studio does not show in devtunnel list, and vice versa.