Recommended environment and recommended character count for Ondoku

Jan. 26, 2026

Recommended environment and recommended character count for Ondoku


The following environment is recommended to use this service. The recommendations for reading aloud are as follows.

Recommended Number of Characters for Reading Aloud

  • Using SSML: Less than 3,000 characters
  • Normal: Less than 5,000 characters

*A warning will be displayed on the input screen if the text exceeds 3,000 characters.

While it is not impossible to read aloud when the number of characters exceeds the recommended limit, such as 10,000 or 20,000 characters, server errors are more likely to occur.

If an error occurs and reading aloud is not possible when using more characters than the recommended limit, we cannot provide support for such errors even if you contact us.

When reading long texts, please try dividing the text into several parts.

If you want to merge separate MP3 files into a single MP3 file, please use an MP3 joining service such as Audio Joiner.

Audio Joiner

Reading Aloud May Not Be Possible If Symbols Are Included

Ondoku is strictly a service that can read characters aloud.

Including unnecessary symbols can interfere with the reading process and may make reading impossible.

Example: & < > : ; " = etc.

In particular, symbols used in SSML tags are prone to causing errors.

Please remove as many symbols as possible that are unrelated to the reading.

If you want symbols to be read aloud, please handle this by replacing them with Katakana or Hiragana.

Example: = Equal

Recommended Browsers

[Windows] Chrome

[MacOS] Chrome

Ondoku recommends Google Chrome as the browser.

If you are experiencing errors:

  • Use Chrome as your browser
    (However, if you are currently using Chrome, please try a different browser)
  • Try using Chrome's Incognito window

Please try the above.

Download Google Chrome

How to Open an Incognito Window

What is an Incognito window?

It allows you to browse without saving website history or form input information.

To use an Incognito window:

  1. Click "File" in the toolbar
  2. Select "New Incognito Window"

Or

  1. Call up using the [Ctrl] + [Shift] + [N] keys

This will open the window.

Please give it a try.

Recommended Internet Speed

  • Upload: 1Mbps or higher
  • Download: 1Mbps or higher

Slow or unstable internet speeds when using Ondoku services may result in:

  • Slower audio generation
  • Unable to listen to audio due to errors
  • Unable to download
  • Slower page loading speeds

This can prevent you from fully enjoying the service.

Output Files

Format: MP3, WAV

*: WAV format can be downloaded from history.

Generated audio files can be downloaded in MP3 and WAV formats.

To download files:

  • Top page: Download button
    　　　　　　The ⋮ button on the player
  • History: MP3/WAV links

They can be downloaded from these locations.

■ AI voice synthesis software "Ondoku"

"Ondoku" is an online text-to-speech tool that can be used with no initial costs.

  • Supports 81 languages and regions, including Japanese, English, Chinese, Korean, Spanish, French, and German
  • Available from both PC and smartphone
  • Suitable for business, education, entertainment, etc.
  • No installation required, can be used immediately from your browser
  • Supports reading from images

To use it, simply enter text or upload a file on the site. A natural-sounding audio file will be generated within seconds. You can use voice synthesis up to 5,000 characters for free, so please give it a try.

Convert text to speech now
Ondoku
Text-to-speech software "Ondoku" can read out 5000 characters every month with AI voice for free. You can easily download MP3s and commercial use is also possible. If you sign up for free, you can convert up to 5,000 characters per month for free from text to speech. Try Ondoku now.
HP: ondoku3.com
Email: ondoku3.com@gmail.com
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Ondoku

"Ondoku" is a Text-to-Speech service that anyone can use for free without installation. If you register for free, you can get up to 5000 characters for free each month. Register now for free

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