Can I deploy my application with that engine on a royalty-free basis?

Soeech Engine Licensing

Can I develop with a Microsoft engine and just deploy my application with that engine on a royalty-free basis? If so, why would someone choose to purchase an engine if they can get one for free?

Yes. You can develop with a Microsoft engine and just deploy your application with that engine on a royalty-free basis.

There may be engine features that are not supported by Microsoft or even SAPI. For example, IBM ViaVoice offers features not found in SAPI. If you are looking at developing continuous speech dictation intensive applications, then you may want to look at other vendors engines.

Microsoft is not sitting idle in this area. SAPI 5 brings new features (and incompatibilities with SAPI4) and Microsoft has acquired another speech technology company. So expect more robust dictation capabilities in the future. Chant provides compatibility across engine APIs and API releases to protect the developer who is using Chant components.