While Chilkat is powerful, consider these alternatives if licensing cost is a barrier:
| Feature | Chilkat | Native .NET | Open Source | | :--- | :--- | :--- | :--- | | MIME/Email | Excellent | Weak (System.Net.Mail) | MimeKit (very good) | | SFTP | Excellent | None (WinSCP wrapper) | SSH.NET | | S/MIME | Excellent | Poor (System.Security) | Bouncy Castle | | REST/HTTP | Good | Good (HttpClient) | RestSharp |
Recommendation: Use chilkatdotnet45.dll when you need all-in-one reliability, cross-version consistency, and support for legacy protocols. Use native libraries for greenfield projects without exotic email requirements. chilkatdotnet45.dll
Alternatively, using NuGet automatically adds the reference and copies the DLL to your output directory.
The 45 in chilkatdotnet45.dll is not a version number (the internal API version is different). It indicates the target .NET Framework. While Chilkat is powerful, consider these alternatives if
Why does this matter? Because .NET 4.5 introduced significant breaking changes in cryptography and TLS. Chilkat had to adapt, but more importantly, the DLL carries its own TLS implementation. It does not rely on Windows SChannel or .NET’s SslStream for heavy lifting. This is a key feature: consistent TLS behavior across Windows Server 2008 R2, 2012, 2016, 2019, and even Linux under Mono.
You have two options:
Cause: A configuration mismatch. Some older Chilkat DLLs were built against .NET 2.0, but modern projects use 4.x.
Solution:
Ensure you are specifically using chilkatdotnet45.dll, not chilkatdotnet20.dll. Remove the old reference and add the correct one. Why does this matter