We follow the pay-as-you-go model, with a free option.
If you select the "Use browser-provided TTS voices" option, the widget will utilize the built-in TTS voices of the user's browser for speech synthesis. This approach incurs no service costs; however, the speech quality may vary among users. Mobile browsers typically offer high-quality voices, whereas the quality in desktop browsers, particularly Firefox, can be quite poor.
If you pick a cloud voice, the cost will consist of:
A typical 6500-character news article synthesizes into approximately 7 minutes of speech and 2.5 megabytes of audio.
Note that an article is synthesized only on the first listen, the audio file is stored in the cloud so subsequent listens incur only content delivery cost. If an article is updated, only the changed paragraphs will be resynthesized.
On the Usage & Costs page, you can monitor your daily usage of each type of cost and drill down to view the events that incurred those costs.
When you first sign up for an account, there's a short trial period during which you can monitor and estimate your monthly cost, before deciding whether to enter your payment information and subscribe to the service.