IIS vs Nginx on Windows Server: Which One Should You Use

Both IIS and Nginx run happily on Windows Server, so the “which one” question is decided by your workload, not by the operating system. The short version: if your application is .NET or needs Windows authentication, use IIS; if you are serving static files, Node.js, PHP, or acting as a reverse proxy at high concurrency, Nginx is often the better fit. This guide compares them feature by feature and gives you a decision checklist. If you are sizing a server for either, compare Windows VPS providers on our comparison table first.

What each web server is built for

IIS (Internet Information Services) is Windows’ native web server, installed as a Windows role and managed through the IIS Manager GUI, PowerShell (WebAdministration/IISAdministration modules), or its XML configuration store. Its strengths come from being part of the platform: application pools isolate applications into separate worker processes, the ASP.NET Core Module hosts .NET apps in-process, Web Deploy integrates with Visual Studio and Azure DevOps, and Windows Authentication plugs directly into Active Directory.

Nginx is an event-driven server originally built for Linux, with official Windows builds. One worker process handles many thousands of concurrent connections using an asynchronous, non-blocking model, which keeps memory usage low under load. Its configuration is a plain text file (nginx.conf) that is trivial to version-control, and its reverse proxy and load-balancing features are first-class rather than add-ons.

Feature comparison

Feature	IIS	Nginx
ASP.NET Framework hosting	Native (FastCGI / ISAPI)	Not supported directly; proxy to a Windows host
ASP.NET Core hosting	Native via ASP.NET Core Module (in-process)	Reverse proxy to Kestrel (standard, well documented)
PHP	FastCGI (php-cgi)	FastCGI — the most common pairing on Windows
Node.js	Via iisnode module	Direct reverse proxy / WebSocket support
Static files	Fast, with HTTP.sys kernel-mode caching	Very fast; event-driven I/O handles high concurrency
Windows / AD authentication	Native (Kerberos, NTLM, AD integration)	None built-in; needs extra modules or a front-end approach
Web Deploy (MSDeploy) publishing	Native	Not available
URL rewriting	URL Rewrite module	Built-in rewrite directives
Reverse proxy / load balancing	Via Application Request Routing (ARR)	First-class, part of the core server
Process isolation	Application pools (crash isolation, recycling)	Worker processes; no per-app pool concept
Configuration	GUI + XML (applicationHost.config, web.config)	Single text file, easy to script and version
TLS / certificates	Schannel; certificate management in the GUI	OpenSSL; config-file based

Performance: what the benchmarks actually mean

Benchmarks that pit Nginx against IIS usually test static-file throughput and concurrent connections, where Nginx’s event loop is genuinely impressive and IIS’s per-request thread model costs more memory. But those numbers rarely decide real deployments. On a typical Windows VPS — 2 to 8 GB of RAM serving a business site or an API — both servers saturate the network long before they run out of headroom; the bottleneck is almost always the application, the database, or PHP-FPM, not the web server itself. If you expect very high concurrency (thousands of simultaneous keep-alive connections, long polling, WebSockets), Nginx holds up with far less memory. For ordinary workloads, choose by features, not by benchmark tables. Whatever you pick, see the full specs and pricing to ensure the plan’s RAM and vCPU match the traffic you expect.

When IIS is the right choice

• Your app is ASP.NET Framework or ASP.NET Core and you want in-process hosting, app pool isolation, and recycling without extra plumbing.
• You need Windows Authentication or Active Directory single sign-on for an intranet application.
• Your team publishes with Web Deploy from Visual Studio or Azure DevOps — the deployment story is simply the smoothest on IIS.
• You prefer managing servers through the IIS Manager GUI and per-site web.config files.

When Nginx is the right choice

• You are serving a static site, a single-page application, or files (downloads, media) where raw throughput matters.
• Your stack is Node.js, Python, or PHP and you want a battle-tested reverse proxy in front of it.
• You run multiple backends on one server and need path- or hostname-based routing, load balancing, and TLS termination in one place.
• Your team lives in nginx.conf and wants the same config file on Linux and Windows servers.

The hybrid setup most Windows VPS users end up with

You do not have to choose. A very common production pattern on a single Windows VPS is Nginx in front terminating TLS, serving static assets directly, and proxying API or application traffic to IIS (or directly to Kestrel). A minimal Nginx server block looks like this:

server {
    listen 443 ssl;
    server_name app.example.com;
    ssl_certificate     C:/certs/fullchain.pem;
    ssl_certificate_key C:/certs/privkey.pem;

    location /static/ {
        alias C:/apps/myapp/wwwroot/static/;
        expires 7d;
    }
    location / {
        proxy_pass http://127.0.0.1:5000;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-Proto $scheme;
    }
}

IIS handles the .NET application pool, Nginx handles TLS, static files, and connection fan-in — each doing what it is best at. If you would rather keep everything in the Microsoft ecosystem, IIS with the Application Request Routing (ARR) module provides the same reverse-proxy pattern with GUI management. Either way, the two servers coexist fine on a 4 GB plan. For a sense of what that costs, review the current Windows VPS plans on our homepage.

A five-question decision checklist

1. Is your application .NET Framework or ASP.NET Core? → IIS (or Nginx in front of Kestrel).
2. Do you need Windows Authentication or AD integration? → IIS.
3. Is the workload static files, a SPA, Node.js, or PHP? → Nginx.
4. Do you expect thousands of concurrent connections or WebSockets? → Nginx.
5. Which one does your team already maintain well? → The server you can operate reliably beats the theoretically faster one.

Licensing and operations

IIS is included free with every Windows Server edition — no extra license, no CAL for the web server role itself. Nginx is open source (with a commercial NGINX Plus offering you do not need for a single VPS). Both are free to run, so cost is not a deciding factor. The practical operational notes: keep Windows patched either way, because both servers sit on the same OS; back up the configuration (the C:\inetpub tree plus applicationHost.config for IIS, or the nginx.conf plus your site files for Nginx); and monitor the same way regardless — CPU, RAM, request latency, and error rates tell you more than any web server marketing slide. When you are ready to provision, our comparison table on the main site lists plans with enough headroom for your stack and your monitoring.