STT4U (“the app”) is a voice input app for Windows. This policy explains what information the app handles, where it sends it, and where it stores it.
1. The developer only receives what you send through the report page
The app has no server operated by the developer. Your voice, transcribed text, settings, and API key are never sent to the developer by the app. The app does not collect usage data and shows no advertising.
Only if you submit the report page (https://stt4u.vercel.app/en/report.html), what you write there (the type, your message, the problematic output, an optional reply email address, and the app version) is delivered to the developer. It is used only to respond to the report and to improve the app, and is not shared with third parties. Delivery uses the email service Resend (https://resend.com). To prevent abuse, the page host (Vercel) temporarily handles the sender's IP address.
2. Information sent to external services
To turn speech into text and clean it up, the app uses the services of OpenRouter (https://openrouter.ai). Communication with OpenRouter uses your own OpenRouter API key. The app sends the following:
| When | What is sent |
|---|---|
| Voice input | The audio recorded from when you press the hotkey until you stop (in preview mode, it is sent in segments while you are still speaking), together with the words in your dictionary and your “usage” settings (to improve recognition accuracy) |
| Cleanup and translation | The text transcribed from your voice, together with the words in your dictionary, your usage settings (what you use the app for, your field, etc.), and the selected instructions |
| Transcription | The contents of the audio file you choose and the text transcribed from it |
| Text-to-speech | The text to be read aloud |
| API key check | Your API key (to check that it is valid and to show your balance) |
OpenRouter passes this information to the provider of the AI model you selected (such as OpenAI, Google, Microsoft, or Alibaba) for processing. How the information is handled is governed by the privacy policies of OpenRouter and each provider. Depending on the provider, information may be processed outside Japan (for example in the United States or China). The app shows the provider’s name on the model selection screens, and also the country for providers based in China.
In OpenRouter’s settings (https://openrouter.ai/settings/privacy) you can, for example, exclude providers that may use your data for training.
3. Information stored on your computer
The app stores the following on your computer (in %APPDATA%\stt4u; the Microsoft Store version may use an app-specific location provided by Windows). None of it is sent anywhere.
| What | Contents |
|---|---|
| Settings | Selected models, dictionary, instructions, usage settings, etc. |
| API key | Encrypted with Windows’ built-in encryption (if encryption is not available, the app tells you and stores it unencrypted) |
| History | Transcribed text and cleaned-up text (by default, the most recent 1,000 entries) |
| Cost records | Models used, costs, character counts, and durations (no text; deleted after 400 days) |
| Last recording | The audio of the most recent recording, kept so you can retry |
| Activity log | The app’s behavior, for troubleshooting. It does not include what you said, unless you turn on “include spoken content in the log” in the settings |
You can delete your history in the app. The folder above may remain after you uninstall the app. To remove everything, delete the folder.
4. Microphone, keyboard, and clipboard
- Microphone: used while recording, during a microphone test, and briefly at startup to prepare the microphone (opened and closed immediately). The app does not use the camera
- Keyboard: the app watches key presses only to detect your hotkey. It does not record or send what you type. For troubleshooting, it may write the codes of keys involved in hotkey handling to the activity log
- Clipboard: the app writes the transcribed text to the clipboard in order to paste it. It never reads the contents of the clipboard
5. Children
The app is not directed at children.
6. Changes to this policy
When this policy changes, this page will be updated along with the “last updated” date.
7. Contact
Publisher: i10.y
Contact: report and contact form