Files & export

Linked Files

Section-Level Linking

Link external text files to any section. Content auto-refreshes when the file changes.

  • Supported formats: .txt, .rtf (rich text converted to inline tags), .md and .markdown
  • File watching: real-time monitoring with multiple fallback strategies
  • Atomic save detection: handles editors that write-then-rename

Per-Grid-Item Linking

In Columns & Rows sections, each grid cell can link to a different external file with independent file watchers.

PDF Export

Appearance Modes

  • Built-in: Light, Dark, Sepia, High Contrast
  • Custom modes: user-defined background and foreground colors
  • Per-document mode override
PDF appearance modes: Light, Dark, Sepia, and a custom color scheme

Page Dimensions

  • Paper presets: Letter, A4, A5, A6, Tabloid
  • Device presets: MacBook Air/Pro, iPad, iPhone, Desktop, Slides
  • Custom: arbitrary width and height
  • Margins: independent top, bottom, left, right

Headers & Footers

Place the section name, font info, page number, date and time, or your own custom text into a left, center, or right slot, on independent top and bottom bands. Hellbox can also print an active OpenType features line that lists every feature turned on for the fonts on the page (for example “Features: salt, ss01, ss02”); it gets its own full-width line so a long list wraps instead of being clipped, and you can place it at the top or bottom. A “Print only” option keeps the timestamp and features line out of the on-screen preview while still printing them on export. Either band can be turned off.

Fit to Page

One-click optimization that calculates the optimal font size, line height, and letter spacing to fill a single page. Uses binary search with 0.5pt precision and adapts its strategy for each section type.

Templates

Built-In Templates

Predefined proof setups organized by category:

  • Hamburgers: spacing tests (Ha/Hh/HH, Hamburgefonts)
  • Spacing: basic character sets, spacing tests
  • Pangrams: 8 variants
  • Kerning: I Ask Jeff, Kerning Trio, Furniture Characters
  • Diacritics: 26 language variants (Afrikaans through Turkish)
  • Script-specific: Greek, Cyrillic
Template picker with built-in proofing templates organized by category

Custom Templates

Save any section as a reusable template (.fps file). Star templates for quick access. Browse by category in the template picker.