1. **Google Text-to-Speech (TTS)**
- **Website:** [Google Text-to-Speech](https://cloud.google.com/text-to-speech)
- **Description:** Google offers a robust text-to-speech service with various voices and languages. It is free to use with some limitations.
2. **IBM Watson Text to Speech**
- **Website:** [IBM Watson Text to Speech](https://www.ibm.com/cloud/watson-text-to-speech)
- **Description:** IBM Watson provides high-quality voices and supports multiple languages. You can start for free with their Lite plan.
3. **Microsoft Azure Text to Speech**
- **Website:** [Microsoft Azure Text to Speech](https://azure.microsoft.com/en-us/services/cognitive-services/text-to-speech/)
- **Description:** Microsoft Azure offers a text-to-speech service with diverse voices and languages. They have a free tier that you can use to get started.
4. **Natural Reader**
- **Website:** [Natural Reader](https://www.naturalreaders.com/online/)
- **Description:** Natural Reader offers a free online text-to-speech tool with various voices. It’s easy to use and great for quick conversions.
5. **ResponsiveVoice**
- **Website:** [ResponsiveVoice](https://responsivevoice.org/)
- **Description:** ResponsiveVoice provides a free voice synthesis service that is web-based and supports a wide range of languages.
6. **VoiceGenerator.io**
- **Website:** [VoiceGenerator.io](https://voicegenerator.io/)
- **Description:** A simple, free tool that allows you to convert text to speech online with a few voice options.
These tools offer a variety of features and capabilities, so you can choose the one that best fits your needs.