9 Best AI Voice Synthesis Software 2026: Free & Paid Comparison

I want to know about recommended AI speech synthesis software!

AI speech synthesis software, which converts text into natural speech, is attracting more and more attention!

Thanks to advancements in AI technology, the quality of speech synthesis software has improved dramatically.

It can generate natural human-like voices with high quality that is incomparable to the mechanical reading of the past.

Web app types that can be used for free and desktop types that are installed on a computer differ in their setup process and operating environments.

In addition to products using AI, there are also products that use conventional speech synthesis engines such as AquesTalk and OpenJTalk.

In this article, we will compare 9 of the latest speech synthesis software products for 2026 based on their types and features!

When choosing, you should check whether it is a web app or desktop type, if it works locally, how much you can adjust the voice, speed, and intonation, and whether character voices can be used.

We will explain the differences between each in detail, so why not find the perfect speech synthesis software for you?

[Free] Recommended AI speech synthesis software you can use right now

If you are looking for speech synthesis software, Ondoku is recommended!

Ondoku is a speech synthesis software that uses the latest AI technology and can be used for free from your browser.

Its feature is that you can easily synthesize high-quality speech right now without any installation required on any environment, including PC, iPhone/iPad (iOS), and Android smartphones.

Even though it is free, it can read up to 5,000 characters, and commercial use is also OK!

It supports multiple languages including not only Japanese but also English, Korean, and Chinese, so you can easily create audio in foreign languages.

If you are unsure which speech synthesis software to choose, why not try Ondoku for free first?

What is speech synthesis software? Basic knowledge explained for beginners

First, we will briefly explain the types of speech synthesis software and the features you should check when choosing one.

Difference between AI reading and conventional speech synthesis methods

Speech synthesis software refers to software that automatically converts input text into audio.

Speech synthesis software includes methods that use AI and methods that use conventional speech synthesis engines such as AquesTalk and OpenJTalk.

Previous speech synthesis software had mechanical vocalizations and felt very unnatural.

However, today, the latest AI technology has made it possible to achieve natural human-like intonation and pausing.

In particular, speech synthesis software utilizing deep learning can now produce realistic and easy-to-understand expressions, much like professional voice actors or narrators.

Detailed customization is also possible, such as adjusting the reading speed and changing the pitch.

Difference between web app type and desktop type

Speech synthesis software comes in web app types used from a browser and desktop types installed on a computer.

Web app type speech synthesis software used from a browser is attractive because it can be used immediately without installation.

With the AI web app Ondoku, you can utilize the latest AI technology regardless of your PC's performance.

Desktop types are installed and used on a computer.

Installation-type speech synthesis software has the advantage of being usable even in offline environments.

When choosing, in addition to whether it is a web app or desktop type, or an AI or conventional method, it is recommended to check the types of voices, adjustments for speed, pitch, and intonation, and support for character voices.

[Free versions available] Comparing 9 speech synthesis software for 2026 by type and features

We will compare 9 products based on whether they are used from a browser or installed on a computer, whether they use an AI or conventional engine, how much you can adjust the voice, speed, and intonation, and whether character voices can be used.

If you want to use it locally, check the supported OS and offline usage conditions for each product.

1. Ondoku | Free speech synthesis software that can read using the latest AI

Ondoku is a high-quality speech synthesis software that adopts the latest AI technology.

If you are looking for speech synthesis software, this is the first option you should try!

It is a web app type software that can be used from a browser, so no tedious installation work is required at all.

Just enter the text and press the button, and you can synthesize a natural audio file in just a few seconds.

Japanese voices can be selected from over 16 types of options, with a wide variety including female voices, male voices, and children's voices.

Listen to 16 types of Ondoku voices for free. Change impressions with pitch changes

Ondoku has 16 types of Japanese voices. Of course, both male and female voices are available. We have made it possible to listen to 8 commonly used Japanese voices and the voices when the pitch of each is adjusted.

It supports multiple languages, making speech synthesis for foreign languages like English, Chinese, and Korean easy.

The reading speed and pitch can also be freely adjusted, so you can create the optimal audio for your purpose.

Since commercial use is also OK, it is ideal for YouTube monetization and business use (Click here for details on commercial use).

Furthermore, Ondoku is free!

It can be used without registration or login, so it is recommended to actually try speech synthesis with the latest AI first.

Why don't you try Ondoku for free as well?

2. VOICEVOX | Speech synthesis software with popular characters like zundamon

VOICEVOX is a desktop speech synthesis software compatible with Windows, Mac, and Linux.

Its biggest feature is the ability to read with popular character voices such as "zundamon", "Shikoku Metan", and "Kasukabe Tsumugi".

It uses deep learning technology, allowing for detailed adjustments of the audio.

The software itself is free and allows for commercial use, but caution is needed as the terms of use vary for each character.

A GPU-compatible version is also provided, allowing for faster processing on high-performance PCs.

VOICEVOX Usage Guide! Detailed explanation from features of free AI speech synthesis software to commercial use

A detailed explanation of everything from the features of VOICEVOX to how to use it and points of caution for commercial use. A complete guide to the free AI speech synthesis software that can read in popular character voices like zundamon.

3. Bouyomi-chan | Speech synthesis software compatible with Yukkuri voices for streaming

Bouyomi-chan is a speech synthesis software widely used in game streaming and live streaming.

It can synthesize speech with the characteristic voice known as "Yukkuri voice."

It also has excellent integration features with streaming software like OBS, making it ideal for reading out comments on YouTube and Twitch.

It is also used as a staple for "Yukkuri Jikkyo" and "Yukkuri Kaisetsu" on Niconico Douga and YouTube.

It is a lightweight free software for Windows that works comfortably even on low-spec PCs.

Because it uses an older version of AquesTalk, commercial use is possible even for free.

The sound quality is mechanical, but its unique personality is why it is a speech synthesis software loved by many creators.

4. SofTalk | A simple speech synthesis software with a long history

SofTalk is a simple free speech synthesis software for Windows.

With a simple interface specialized for basic functions, even beginners can use it easily.

You can choose from multiple speech synthesis engines, allowing you to select a voice that suits your needs.

*It previously supported "Yukkuri voices," but it is currently not supported.

The software itself is free, but if using it for commercial purposes, you need to check the terms of the specific voice engine you use.

This is a free software ideal for those seeking basic speech synthesis functions.

5. COEIROINK | AI speech synthesis software for creative activities

COEIROINK is an AI speech synthesis software developed for creative activities.

It is a desktop type compatible with Windows, Mac, and Linux, and can read in various character voices.

In addition to official and authorized characters, user-created voice models "MYCOE" can also be used.

Commercial use is possible, but credit notation is mandatory.

Additionally, since terms of use differ for each voice model, checking before use is important.

This is a speech synthesis software suitable for those seeking unique voices for creative purposes.

What is COEIROINK? Thorough explanation of features, usage, and commercial use

A complete guide to COEIROINK's features and usage. Explains in detail everything from how to install the software to adding character voices and points of caution for commercial use.

6. TextTalk | Lightweight speech synthesis software for Windows

TextTalk is a lightweight and simple free speech synthesis software for Windows.

It uses OpenJTalk and the standard Windows speech synthesis engine.

While the naturalness of the voice has limits compared to the latest AI, it has sufficient performance for basic reading.

It is a software that can be used just by extracting a ZIP file, and it operates comfortably even in old PCs or low-spec environments.

7. A.I.VOICE | Paid speech synthesis software supporting popular VOICEROID characters

A.I.VOICE is a high-quality paid speech synthesis software developed by AI Inc.

It is the successor to VOICEROID, and currently A.I.VOICE2 is being rolled out.

The biggest feature is the lineup of popular character voices such as "Yuzuki Yukari" and "Kotonoha Akane/Aoi".

It is compatible with both Windows and Mac and is sold as a one-time purchase paid speech synthesis software.

Commercial use by individuals is generally possible with product purchase, but business use requires a separate license.

This is a speech synthesis software ideal for creating creative audio works and high-quality narrations.

A.I.VOICE2 Complete Guide! Detailed explanation of VOICEROID successor features, installation, and usage

Explains the features and usage of A.I.VOICE2, where you can use Kotonoha Akane/Aoi and Yuzuki Yukari, familiar from VOICEROID videos. Introduces everything from installation to audio export in detail.

8. CeVIO AI | Highly expressive paid speech synthesis software with popular characters

CeVIO AI is a speech synthesis software that combines reading and singing functions.

It is sold as paid speech synthesis software exclusively for Windows.

Its feature is the ability to use various popular character voices with rich personalities, such as "Sato Sasara" and "Suzuki Tsuzumi".

With its unique speech synthesis AI, it can read text with rich emotion.

In addition to "Talk Voice" for reading, "Song Voice" for singing is also available, supporting both reading and singing.

Commercial use conditions for individual creators are relatively lenient, but business use requires a separate license.

This is a speech synthesis software recommended for those who want to create audio content with rich expressiveness.

What is CeVIO AI? Detailed explanation of speech synthesis software features, usage, and commercial use

A complete guide to the AI singing synthesis software CeVIO AI. Explains the characteristics of popular characters like Sato Sasara and Suzuki Tsuzumi, how to purchase, and points of caution for commercial use for beginners.

9. VOICEPEAK | Paid speech synthesis software with a wide variety of characters

VOICEPEAK is one of the few desktop speech synthesis softwares that supports Linux in addition to Windows and Mac.

This also allows for speech synthesis with various popular characters.

A feature is that there are packages that include multiple character voices, and the lineup includes plenty of male voices as well as female voices.

While commercial use rights are included in the basic license, separate terms apply to character voices.

It is ideal for narration production and speech synthesis across multiple platforms.

What is the speech synthesis software VOICEPEAK? Detailed explanation of features and commercial use

A detailed explanation of the features of the speech synthesis software "VOICEPEAK". Also introduces commercial use terms, which vary greatly by character.

[Free] How to use speech synthesis software? Detailed explanation of how to use Ondoku

How do you use speech synthesis software? Is it easy to use?

From here, we will explain how to actually use speech synthesis software, using Ondoku as an example!

[Free] Flow of reading text with speech synthesis software Ondoku

If you are going to use speech synthesis software, we recommend web app type speech synthesis software which can be used easily without installation!

To read text with Ondoku, first access the official website.

When you open the top page, there is a text box, so enter the content you want to read.

(Copy and paste is also OK)

Next, select the type of voice.

You can listen to the voices available on Ondoku in this article, so please take a look!

Listen to 16 types of Ondoku voices for free. Change impressions with pitch changes

Ondoku has 16 types of Japanese voices. Of course, both male and female voices are available. We have made it possible to listen to 8 commonly used Japanese voices and the voices when the pitch of each is adjusted.

Then just click or tap the "Read" button!

High-quality audio is completed in just a few seconds.

Audio files can be downloaded in MP3 format, so you can use them for various purposes such as video narration or in-store announcements.

As you can see, the free speech synthesis software Ondoku is very easy to use.

If you are looking for speech synthesis software, why not start by using Ondoku?

Ondoku also allows adjustment of reading speed and pitch

The speech synthesis software Ondoku also supports adjustments for reading speed and pitch!

It is effective to adjust the reading speed according to the importance of the content.

When using it for language study, it is also recommended to boldly lower the speed all at once.

When using it for video narration, adjusting the pitch of the voice is also recommended.

By changing the pitch, you can create a character persona that suits the listener.

What are the pros and cons of AI speech synthesis software?

When using speech synthesis software, it is also recommended to clearly understand the pros and cons.

We will briefly explain the pros and cons of AI speech synthesis software.

What are the pros of AI speech synthesis software?

The biggest merit of speech synthesis software is that it can reduce costs.

If you request a professional narrator, many costs are incurred, such as recording fees, studio fees, and travel expenses.

However, if you choose a speech synthesis software that can be used for commercial purposes for free, you can significantly save on these costs.

Another big merit is being able to shorten the time it takes to create audio.

Until now, trying to make a video narration or in-store announcement required a lot of time for booking recording, re-recording, and editing work.

But with speech synthesis software, audio is completed in just a few seconds just by entering text.

High-quality audio can be created for free at any time

High audio quality is also a merit of AI speech synthesis software.

When a human reads, quality can vary depending on physical condition or mood.

Also, if you record it yourself without hiring a pro, it might end up being very hard to hear...

In that regard, with speech synthesis software, you can always generate audio of the same quality.

There is also no worry about sound quality worsening due to recording equipment or the surrounding environment.

Another advantage unique to speech synthesis software is that it is available 24/7.

You can create audio as soon as you think of it, even in the middle of the night or early morning.

With multi-language support speech synthesis software, you can also easily create narrations in foreign languages.

Cons of AI speech synthesis software

Speech synthesis software also has some cons.

Depending on the software, there may be limits to emotional expression.

If you are dissatisfied with the expression, it is also recommended to try using a speech synthesis software that uses the latest AI for free.

Caution is also needed for commercial use.

Since there are paid softwares with restrictions on commercial use, let's check the terms of use in advance.

When you want to use it for video monetization or business, softwares that can be used for commercial purposes for free, starting with Ondoku, are ideal.

What you can do with Ondoku. About commercial use (business use) and prohibited acts.

Commercial use (business use) is possible with Ondoku. Use for the purpose of obtaining profits such as money directly or indirectly, regardless of whether you are an individual or a corporation, is commercial use. However, please note that prohibited acts are established in Ondoku. This time, what you can and cannot do with Ondoku...

How to choose speech synthesis software explained by purpose

Finally, we will explain in detail the points for choosing software that fits the audio you want to create by purpose.

How to choose for video production and YouTube narration

When putting narration into video production, check if it can read with a natural voice and if character voices can be used.

It is important to choose software where you can adjust the type of voice, reading speed, and pitch according to the content of the video.

Another point is to choose a speech synthesis software that allows commercial use, corresponding to monetization on YouTube and the like.

With Ondoku's high-performance AI speech synthesis engine, you can create easy-to-hear audio like a professional narrator.

What's important in video production is adjusting the reading speed according to the content.

It is effective to set important parts slightly slower.

How to quickly create narrations for videos like YouTube with text-to-speech software. Tips and points

Explains how to quickly create YouTube video narrations with Ondoku. From how to make a script to using Ondoku, adjusting natural intonation, and tips for editing with video editing software, explained clearly. A must-see for those who want to streamline video production with text-to-speech software!

How to choose for language learning materials

When making materials for language learning, it is recommended to choose software that supports the audio of the language you want to learn.

By using Ondoku, which supports multiple languages, you can accurately study the pronunciation of various languages.

Creating materials for shadowing, which is effective for language learning, is also easy if you have speech synthesis software.

You can also create foreign language listening materials.

The point when making materials for language learning is to make the playback speed slow at first.

Ondoku can lower the playback speed down to 0.3x, so it is also ideal for those who have just started studying a foreign language.

[Complete Guide] What is the way to do English shadowing? Also explains how to make free materials!

Efficiently improve your English skills with shadowing! A learning method that simultaneously improves listening, pronunciation, and speaking, explained for beginners. Also introduces how to create materials with free AI audio.

How to choose when making audio for business use

When using for corporate business purposes, check if it can be used for commercial purposes, if it can read out the necessary languages, and if it can be used locally.

• Converting presentation materials to audio
• Adding audio to internal training materials
• Guidance audio for call centers
• Announcements within facilities

As you can see, speech synthesis software can be used for a wide range of purposes.

If you use a speech synthesis software that can read out foreign languages, you can also easily create announcements for inbound tourists in English, Korean, Chinese, etc.

For companies that emphasize security, Ondoku, a service from Japan, is reassuring.

Even when used for business, be careful to use a speech synthesis software that supports commercial use.

Achieve professional-level in-facility broadcasts with automated audio! AI Announcement Complete Guide

Automate in-facility broadcasts with AI! With Ondoku, create narrator-level automated audio for free. Full support for inbound measures with multi-language capability. Also contribute to cost reduction through business efficiency!

Game streaming and live streaming

When using speech synthesis software in live streaming, real-time reading is important.

By integrating a streaming-specialized speech synthesis software like Bouyomi-chan with OBS, you can check comments without taking your eyes off the screen.

By utilizing the feature to read out viewer comments, you can also liven up the streaming content even more.

Improving accessibility

Speech synthesis software is also a very important tool for people with visual impairments or learning disabilities.

By converting website text into audio, more people will be able to access digital information.

In addition to people with disabilities, usability can also be improved by introducing speech synthesis software in services for the elderly.

When creating audio that is easy for anyone to hear, check if you can adjust reading speed and pitch in addition to a natural voice.

With a high-quality AI speech synthesis software with a realistic voice, you can create audio that is hard to get tired of even when listening for a long time.

For accessibility support for corporate or organizational websites or creating guidance broadcasts for public facilities, the latest AI speech synthesis software is recommended.

Summary of how to choose speech synthesis software

As AI technology has advanced, anyone can now easily create high-quality audio with speech synthesis software.

If you want to create audio immediately, we recommend the web app type; if you want to use it without connecting to the internet, we recommend the desktop type that operates offline.

Even with the same desktop type, the naturalness of the voice changes greatly depending on whether you choose the AI method or the conventional method.

When you want to check the features of each software, please take a look at the comparison table introduced in this article.

If you are considering commercial use, such as YouTube monetization, it is also important to carefully check the terms of use and use a speech synthesis software that allows commercial use.

With Ondoku, you can experience speech synthesis easily right now for free and without installation.

Why not experience a speech synthesis software that you can use for free first?