Lets start on what you want to use text to speech for? I use text to speech for WBT s. I use Adobe Captivate to creat e-Learning classes. I use the voices downloaded from Adobes website. I believe they come from neo speech. http://www.neospeech.com. They were free to me as I have Captivate already. From the website, they don t apprear to be free.

I have two options:

1.) Android s PicoTTS outperforms Festival, FreeTTS, and eSpeak by a long shot. Don t have an Android device? You can hear a short clip in this video to decide if you agree.

If you like PicoTTS well enough, Android has a synthesizeToFile() method that can save the audio stream to WAV. I m not aware of any apps that use this feature, but you want to build a web service, so you d probably have to hack in the Android java source code anyway.

2.) The next option is to use Google Translate, e.g. http://translate.google.com/translate_tts?tl=en&q=hello+world.

This works great for strings less than 100 characters. Longer strings would have to be sent in chunks, but there is an app on The Code Project (with source) that already does this pretty well.

Have you tried Loquendo?

Update: I just noticed the free requirement... Fulfilling both realistic and free is a bit difficult, but if you consider voices coming with the OS as free, then Windows Vista and Windows 7 have very impressive voices (unlike XP s).

I have been searching all around and one that I have found that is FREE and has some alright voices is yakitome.com1. This fit perfectly for what I needed(convert text to a .wav file with a better voice than the Microsoft sam crap using a free program ). You can choose among some voices(the best was AT&T s "natural voices") and create a file. The best part is that you can save it as a mp3 or a wav file. Just follow the directions under the FAQ s. There is also a survey and they talk about adding some awesome voices for free.(they would purchase them) Anyways just wanted to share some info because this is the best I ve found all week and I ve downloaded about 8 programs so far.

YAKiToMe! http://www.yakitome.com is free and has really good voices and adding new ones in multiple languages. I use the site to listen to pdf files and RSS feeds. They can also read email, .txt, html, etc. There s no software to download. It s a cloud-based implementation. They have a well-documented API. Audio books made with YAKiToMe! can be downloaded or shared online. It s a quality service and they never spam me. Did I mention it s free and you can input large texts?