# Files

> For the complete documentation index, see [llms.txt](/llms.txt)

> Upload documents in PDF, Word, Excel, and other formats

Upload documents directly to your project. Biel.ai indexes their content for chat responses.

:::tip
Uploaded files remain private. Your assistant does not expose a link to the stored file as a source.
:::

## When to use file uploads

Use file uploads for:

- Internal documents such as handbooks, policies, and procedures
- Offline content that is not published on the web
- PDF manuals, Office documents, and spreadsheets
- Confidential content that needs to stay private

## Supported formats

| Format | Extensions |
|--------|------------|
| PDF | `.pdf` |
| Word | `.docx` |
| PowerPoint | `.pptx` |
| Excel | `.xlsx` |
| Delimited data | `.csv` |
| Markdown and text | `.md`, `.txt` |
| Structured data | `.yaml`, `.yml`, `.json`, `.xml` |
| Documentation and web files | `.rst`, `.html`, `.css`, `.js` |

## Requirements

- Each file can be up to 10 MB.
- Use the listed extension. Legacy Office formats such as `.doc`, `.xls`, and `.ppt` are not supported.
- Files must not be empty or password-protected.

## Upload files

1. In the [Biel.ai dashboard](https://app.biel.ai), select an existing project. Files are available after you create the project.
2. Go to **Settings** > **Sources** > **Files**.

    ![The Files tab of the Sources settings page with the upload area](../images/settings-sources-files.jpg)

3. Drag files into the upload area, or click **Browse files**. Files upload automatically; wait until they appear in the uploaded-file list.
4. Click **Refresh sources** to index the files. Check the loading status and **Logs** in the project dashboard.

## How files are indexed

Biel.ai processes PDF, Word, and PowerPoint files page by page. It processes each Excel sheet separately. This keeps retrieved content aligned with the page or sheet where it came from.

Scanned PDFs are processed with OCR. Clear, high-resolution scans generally produce better results than low-quality scans or pages with difficult layouts.

## Manage files

For text and HTML files, use the **Preview** or **Edit** icon next to the file. After editing, click **Save** in the editor. For other formats, delete the old version and upload the replacement. Click **Refresh sources** after changing files to index the current set.

Use the **Download** icon next to an uploaded file in **Settings** > **Sources** > **Files** to retrieve the original file. To remove a file, click its **Delete** icon.

## Troubleshooting

### Upload failures

- Check that the file is no larger than 10 MB.
- Verify the file format is [supported](#supported-formats).
- Check that the file is not empty, corrupt, or password-protected.

### Content not indexing

- Refresh sources after upload, then allow the crawl to finish.
- For scanned PDFs, use a clear scan with legible text.
- If a large document is only partly indexed or a crawl reports that files were skipped, try refreshing sources again. [Contact us](https://biel.ai/contact) if the problem continues.