XeFM’s built-in file viewer can render JSON / JSON Lines files as a collapsible tree and CSV / TSV files as an aligned table, in addition to the usual raw, line-numbered text view. They work exactly like the Markdown viewer: press V to open a file, then M to toggle between the raw text and the rich view.
*.json, *.jsonl, *.ndjson)The rich view is a collapsible tree. Objects and arrays are branches you can
expand and collapse; scalars are leaves. Each row shows its key (an object key or
an array index) and the value, colored by type — strings, numbers, and
true / false / null each get their own color, following the active theme.
A collapsed branch shows its size ({3} for a 3-key object, [5] for a 5-item
array), so you can see the shape of a document without expanding everything.
A .jsonl / .ndjson file (one JSON value per line) is shown as an array of its
records.
Selecting a fragment with the mouse. Selection in the tree is structural:
a click or drag always selects a meaningful piece of JSON — never half a word or
a stray text span. Click a key to select "name", a value to select "str" /
123 (or, on a branch row, the whole {...} / [...] sub-document), or the
: between them to select the whole "name": ... entry. Drag to grow the
selection: across a key and its value it becomes the entry, across two rows it
becomes the container that holds them both, and across two top-level entries the
whole document. ⌘C / Ctrl+C copies the highlighted fragment as JSON text;
with nothing highlighted it copies the current row’s value, as before. Arrow
keys or a click on empty space clear the highlight. (Array indices aren’t JSON
text, so clicking one selects the element’s value.)
Long values. A string longer than the window has two ways to be read. Unwrapped (the default), the view pans horizontally — swipe sideways on a trackpad or press Shift+←/→, with a horizontal scrollbar along the bottom while something overflows. Press W to wrap instead: every value folds into the window width, continuing on extra lines aligned under where it starts, so the whole string is on screen at once. The header shows WRAP while wrap is on, and W toggles back.
| Key | Action |
|---|---|
| ↑ / ↓ | Move up / down a row |
| → | Expand a branch (or step into it) |
| ← | Collapse a branch (or jump to its parent) |
| Enter / Space | Toggle the selected branch |
| PgUp / PgDn, Home / End | Scroll by a page / jump to the top or bottom |
| W | Toggle line wrap for long values |
| Shift+← / Shift+→ | Pan a long row sideways (when wrap is off) |
| Mouse wheel / click | Scroll / select a row (click the ▸ ▾ marker to toggle) |
| Click / drag on text | Select a JSON fragment (key, value, entry, or container) |
| ⌘C / Ctrl+C | Copy the fragment — or, with none, the row’s value — as JSON |
| F | Incremental search |
*.csv, *.tsv)The rich view is an aligned table with ruled grid lines. The header row stays
frozen at the top while the body scrolls, columns are sized to their content
(numeric columns right-align), and the grid scrolls both vertically and
horizontally so wide tables stay readable. A .tsv file is split on tabs, a
.csv file on commas.
The grid lines follow the display: on the graphical app they’re crisp
device-thin rules around every cell; on the terminal they’re box-drawing
characters (│ column separators and a ├─┼─┤ line under the header), with the
body rows zebra-striped for separation.
| Key | Action |
|---|---|
| ↑ / ↓ / ← / → | Move the current cell |
| PgUp / PgDn | Scroll a page |
| Home / End | First / last column |
| Mouse wheel | Scroll (vertical, and horizontal on a trackpad) |
| Click + drag | Select a rectangular block of cells |
| ⌘C / Ctrl+C | Copy the selected cells as TSV |
| ⌘A / Ctrl+A | Select the whole table |
| F | Incremental search |
.json
file to the tree and every .json opens as a tree afterward, this session and
after a restart. The header’s top-right shows the current view’s name (JSON /
Table); the footer shows the toggle key..json doesn’t parse (or a file
otherwise can’t be rendered), M simply leaves you in the raw text view —
which still shows the file with syntax highlighting — rather than failing.