Command line

Hellbox ships with a command line interface for rendering proofs without opening the app. Point it at font files and get a finished PDF, or automate exports and render checks on saved .fontproof documents.

Setup

The CLI lives inside the app bundle. Add an alias to your shell profile:

alias hellbox="/Applications/Hellbox.app/Contents/MacOS/Hellbox"

Proof from Font Files

hellbox --proof renders a template-based proof straight from font files:

hellbox --proof MyFont.otf MyFont-Italic.otf proof.pdf

Pass one or more fonts followed by the output PDF path. Only compiled fonts are supported (.otf, .ttf, .ttc, .otc). Requires an active license or trial.

Flags:

--template "Name": which proof template to use. Default is “Pangram Proof”. Run --list-templates to print the available names.
--separate: write one PDF per font instead of one combined proof.
--instances "Bold,Black Italic": choose variable-font named instances. Default is all named instances.
--save-doc: also write the .fontproof document next to the PDF, so you can open it in Hellbox and refine it.

hellbox --proof renders a variable font’s named instances straight to a finished PDF

Document Commands

These work on saved .fontproof files and have no license gate:

hellbox --export in.fontproof out.pdf: export a saved document to PDF.
hellbox --render-check in.fontproof: print JSON diagnostics, page count, page dimensions, character-coverage issues, and overflow issues.
hellbox --render-pngs in.fontproof outDir [scale]: render each page to a PNG in outDir. Default scale is 2x.

Recipes

Proof every font in a folder, one PDF each:

hellbox --proof Fonts/*.otf proofs.pdf --separate

Regenerate a proof after each export from your editor, re-run the same command whenever your font editor writes a new binary:

hellbox --proof build/MyFont-VF.ttf proof.pdf --template "Pangram Proof"

CI-friendly render checks, fail a pipeline on coverage or overflow issues by inspecting the JSON:

hellbox --render-check proofs/brand.fontproof

For AI-assistant workflows, see the MCP server page. The CLI covers terminal and scripting workflows; MCP lets tools like Claude create and modify proofs conversationally.

Source fonts in saved documents

Saved .fontproof documents can reference .glyphs and .glyphspackage sources for headless rendering. Hellbox compiles them with its bundled fontc; the runner does not need Glyphs, Python, or fontmake. Commit the sources alongside the proof and preserve their relative locations. Named instances render at their own coordinates.

This applies to document commands such as --export and --render-check; --proof accepts the compiled font formats listed above.