# Previewing files

Updated: 2026-11-11

A click on a file opens it **inside IT4S, read only**, instead of a download or a new tab.

## Where

- On an issue: the **Attachments** tab (the picture or the file name). It lists the files of the description and of the comments too.
- On a documentation page: the **Files** tab and the file chips in the text and in the comments.
- **Ctrl+click** (⌘+click on a Mac) or the middle mouse button still opens the file in a new tab.

## The preview

- On top: the type (*PDF*, *CSV* …), the name, size, who added it and when; **‹ 2 of 6 ›** to go through all files of the issue or page; **Download**; **Open in a new tab**; **×** (or `Esc`) closes.
- **← →** switch to the previous or next file; the strip at the bottom shows all of them, a click opens one.
- On a phone the preview takes the whole screen.

| File | Shown as |
|---|---|
| Images (PNG, JPG, GIF, WebP, SVG) | fitted to the window. **+ / −**, *Fit* and *100 %* zoom; a click switches between fitted and 100 %, dragging moves a large image. |
| PDF | the browser's PDF viewer, with its own pages, zoom and search |
| Markdown (`.md`) | formatted like a documentation page; **Rendered / Source** switches to the text |
| CSV | a table with a fixed header and row numbers. The delimiter (`,` `;` or tab) and the character set are detected and shown; at most 5,000 rows, then a note and the download |
| JSON | formatted, with line numbers and colours |
| Text (`.txt`, `.log`, `.yaml`, `.xml` …) | with line numbers; **Wrap lines** on or off |
| Anything else (Word, Excel, e-mails, ZIP …) | *No preview for this file type* and **Download** |

- Text, Markdown, CSV and JSON above **5 MB** say *Too large for the preview* and offer the download.
- Text is read as UTF-8; files saved in the old Windows character set (umlauts from Excel exports) are recognised too.
- The preview shows exactly what the download gives you, with the same rights: whoever may not see the file does not see the preview either. Nothing in a file runs inside IT4S.