WinINet vs. WinHTTP
With a few exceptions, WinINet is a superset of WinHTTP. When you're choosing between the two, you should use WinINet unless you plan to run within a service or service-like process that requires impersonation and session isolation.
Comparison of features
| Feature | WinINet | WinHTTP |
|---|---|---|
| Credential cache. Allows all built-in applications in Windows Internet Explorer to get credentials automatically. It also allows an application running outside of Internet Explorer to prompt/specify the credentials for the server only once. From then on the requests are automatic. | yes | no |
| Credential prompting. Provides an API that allows the calling code to prompt the user for credentials. | yes | no |
| FTP | yes | no |
| Autodial/RAS support. This is legacy functionality. Use Remote Access instead. | yes | no |
| Zones. Automatic integration with Internet Explorer security zones. | yes | no |
| IDNA support. Integrated support for the IDNA RFC/Punycode. | yes | yes |
| Cookie Jar APIs. Persistent and non-persistent cookies are supported. Any application or script can use this to see the same cookies as the browser. | yes | no |
| Protected mode IE support | yes | no |
| Decompression support. Support for gzip and deflate compression scheme. | yes | yes |
| Chunked upload support. Client code must perform the chunking. | no | yes |
| SOCKS4 (SOCKS version 4) support. Doesn't include v4a. | yes | no |
| SOCKS5 (SOCKS version 5) support | no | no |
| Bidirectional send and receive | no | no |
| Overlapped I/O | no | no |
| File scheme support. Useful for proxy scripts with a file scheme. | yes | no |
| InternetOpenUrl. Simplified code to open a URL. | yes | no |
| Services support. Can be run from a service or a service account. | no | yes |
| Session isolation. Separate sessions do not impact each other. | no | yes |
| Impersonation. Supports being called while the thread is impersonating a different user. | no | yes |