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SPECIFICTION
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Bitmap Font Editor

github.com

WindowsmacOSLinux
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Spec score 7.8 #14 of 33 in Font Design Software

What it is

Bitmap Font Editor is a free desktop tool for creating monochrome bitmap fonts, particularly for retro computers and embedded targets such as the SAM Coupe. It supports fixed-width and variable-width fonts, with adjustable advance width for each glyph. Users draw glyphs in cells up to 32×32 pixels by clicking or dragging to paint and erase; draggable font guides and pinned reference glyphs are also available. Editing tools include undo, redo, copy, paste, clear, invert, flip, and shift. An editable sample text preview offers three zoom levels and white-on-black or black-on-white display. Raw font bitmaps can be imported with settings for starting codepoint, geometry, and byte layout. Projects use the losslessly round-trippable .fnt.json format. Export produces a 1bpp bitmap plus JSON sidecar files for widths and character mapping. Release 0.1.3 offers Windows, macOS, and Linux builds, with SHA-256 checksums. The source is MIT-licensed. Windows and macOS builds are unsigned, and system-font filling is disabled because Canvas 2D lacks TrueType hinting access.

Spec sheet

Purpose
Font Editor is a desktop editor for monochrome bitmap fonts, aimed at retro and embedded targets.Read 7 Oct 2026 · github.com
Intended users
The project describes itself as aimed at old home computers, particularly the SAM Coupe, and retro or embedded targets.Read 7 Oct 2026 · github.com
Platforms
The project describes Windows, macOS, and Linux packaging targets, and says it was developed and used on Windows 11.Read 7 Oct 2026 · github.com
License
The repository source is covered by the MIT license.Read 7 Oct 2026 · github.com
Maker
The GitHub profile identifies spectecjr as Simon Cooke and lists Seattle, WA.Read 7 Oct 2026 · github.com
Disabled feature
Filling glyphs from an installed system font is currently disabled because Canvas 2D lacks TrueType hinting access.Read 7 Oct 2026 · github.com
Download verification
Release 0.1.3 includes SHA-256 checksums for its downloadable builds.Read 7 Oct 2026 · github.com
Drawing
Glyphs can be drawn in cells up to 32×32 pixels, with draggable font guides and pinned reference glyphs.Read 7 Oct 2026 · github.com
Editing tools
The editor includes undo and redo, glyph copy and paste, clear, invert, flip, and shift operations.Read 7 Oct 2026 · github.com
Export
Font export writes a 1bpp bitmap plus JSON sidecar files for widths and character mapping.Read 7 Oct 2026 · github.com
File formats
Projects use losslessly round-trippable .fnt.json files, and export produces a bitmap binary plus widths and codepoint mapping JSON files.Read 7 Oct 2026 · github.com
Font types
It supports variable-width and fixed-width fonts.Read 7 Oct 2026 · github.com
Font widths
It supports variable and fixed-width fonts, with an adjustable advance width for each glyph.Read 7 Oct 2026 · github.com
Glyph drawing
Glyphs can be drawn in cells up to 32×32 pixels by clicking or dragging to paint and erase.Read 7 Oct 2026 · github.com
Import
Raw font bitmap import lets users configure the starting codepoint, geometry, and byte layout.Read 7 Oct 2026 · github.com
Intended audience
The maker describes the editor as intended for bitmap fonts for old home computers and retro or embedded targets.Read 7 Oct 2026 · github.com
Notable limitation
Fill From System Font is disabled because Canvas 2D lacks real TrueType hinting and the small-size results are not good enough.Read 7 Oct 2026 · github.com
Platform caveat
The maker says macOS and Linux paths should work but are not regularly exercised.Read 7 Oct 2026 · github.com
Platform downloads
Release 0.1.3 provides Windows, macOS for Intel and Apple Silicon, and Linux builds.Read 7 Oct 2026 · github.com
Preview
Editable sample text can be previewed at three zoom levels in white-on-black or black-on-white.Read 7 Oct 2026 · github.com
Saved projects
Projects use the `.fnt.json` format, which the project describes as lossless.Read 7 Oct 2026 · github.com
Signing
The maker says builds are not code-signed; Windows may show a SmartScreen warning and macOS requires removing quarantine after download.Read 7 Oct 2026 · github.com
Unsigned builds
Windows and macOS builds are unsigned, so first run shows a SmartScreen or Gatekeeper warning.Read 7 Oct 2026 · github.com

Strong points and limits

Strong points

  • Free, MIT-licensed source
  • Supports fixed-width and variable-width fonts
  • Exports bitmap data and JSON sidecars
  • Available for Windows, macOS, and Linux
  • Release downloads include SHA-256 checksums

Limits

  • Windows and macOS builds are unsigned
  • System-font glyph filling is disabled
  • macOS and Linux paths are not regularly exercised

Who it suits

It suits people making monochrome fonts for retro computers or embedded targets, especially the SAM Coupe. Its variable-width support and glyph-level drawing tools may also suit other bitmap-font projects.

Verdict

Bitmap Font Editor covers glyph drawing, preview, import, and bitmap export in a free desktop application. Note the unsigned Windows and macOS builds and the disabled system-font fill feature.

Where Specifiction places it

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