An online bitmap font editor for retro computing character sets. Edit pixel-level glyphs in variable-size fonts, preview text with authentic color palettes, and import/export across 20+ formats.

Try it now at https://damieng.github.io/ch8ter/

• Open and edit multiple fonts simultaneously in floating, draggable windows
• Variable glyph dimensions from 1x1 up to 32x32 pixels
• Auto-save to browser localStorage with dirty-state tracking
• Monospace and proportional spacing modes

Load (auto-detected from extension and content):

Save:

Export:

• Interactive pixel editor opens on glyph click, follows selection, closable
• Adjustable zoom on both the pixel editor and the character grid
• Per-glyph transforms: flip horizontal/vertical, rotate CW/CCW, invert, shift in all directions, center horizontally
• Multi-select glyphs with click, Shift+click range, Ctrl+click toggle
• Quick select by category: all, numbers, uppercase, lowercase, symbols, invert selection
• Batch transforms on entire selections
• Clipboard support: copy/paste/cut glyph data as ASCII art
• Undo/redo with up to 100 steps per font (Ctrl+Z / Ctrl+Y)
• Metric guidelines in the editor: baseline, ascender, cap height, x-height, numeric height, descender

• Generate bold variant (pixel expansion)
• Generate outline variant (border detection)
• Generate oblique variant with adjustable shear angle
• Generate proportional variant: shifts each glyph to the pixel edge and sets per-character advance widths
• Generate monospace variant from a proportional font: choose target width and pixel alignment (left/center/right)
• Resize all glyphs with configurable anchor (top/center/bottom, left/center/right)
• Copy character ranges (e.g. uppercase to lowercase)

• Per-glyph advance widths loaded from BDF, FZX, PCF, PDB, Amiga, and Atari ST GDOS fonts
• Drag the green advance-width guide in the glyph editor to adjust a character's width
• Unicode fixed-width ranges (box drawing, block elements, etc.) always render at full cell width
• Proportional and monospace preview rendering

• Live text preview windows with custom or sample text
• Automatic proportional or monospace rendering based on font spacing mode
• 50+ built-in sample texts: pangrams, character sets, classic game text, code samples (BASIC, C, Pascal, Z80 assembly, 6502 assembly), literature excerpts
• Adjustable zoom and line height
• Text selection and cursor with click, drag, double-click word select, triple-click select all

Character sets: ASCII, Amiga (ISO-8859-1), Amstrad CPC, Amstrad CP/M Plus, Atari 8-bit, Atari ST, BBC Micro, Commodore 64, DOS (CP437), DOS (CP850), ISO 8859-1 through 8859-16, MSX International, PalmOS 3.3, SAM Coupe, Windows-1252, ZX Spectrum

Color palettes: Acorn BBC Micro, Amstrad CPC, Apple II, Atari 8-bit, Commodore 64, Commodore Plus/4, Commodore VIC-20, MSX (TMS9918), Nintendo NES, SEGA Master System, SAM Coupe, Sinclair QL, ZX Spectrum, Custom

Import: auto-detection of glyph dimensions, scale factor, gap and border sizes with live grid overlay preview

Export: configurable scale, column count, gap/border sizes, foreground/background colors, transparent background, division and border colors

Batch convert fonts from the command line:

ch8ter convert <input-file> <format> [output-file] [options]

Output formats: ch8, bdf, psf, yaff, draw, fzx, gdos, pcf, pdb, atari8, amiga, ega, bbc, cpm

Options: --width, --height, --start-char, --name, --baseline

Input format is auto-detected. Gzip-compressed inputs (.gz) are decompressed transparently.

npm install
npm run dev

Vite + Preact + @preact/signals + TypeScript + Tailwind CSS + Lucide icons

Claude Code was used extensively in the creation of this tool.

MIT