What is the MF file format?
.mf is a plain-text source file written in the Metafont programming language, created by Donald E. Knuth as part of the TeX typesetting system. Rather than describing glyphs as fixed outlines, a .mf file defines letterforms programmatically using pen strokes, curves, and parametric equations - letting a single source file generate fonts at any resolution or optical size by adjusting variables.
To produce usable output, a .mf file is compiled by the mf command-line program (included in distributions such as TeX Live and MiKTeX). The compiler takes the source along with a mode specification (e.g., ljfour for a LaserJet at 600 dpi) and produces two outputs:
- A .TFM metric file that TeX reads for character widths, heights, and kerns.
- A .GF or .PK bitmap file containing rasterized glyphs at the target resolution.
The files are ASCII text with no magic bytes or binary header. Typical statements include mode_setup;, beginchar(...);, pickup pen;, and endchar;, ending the program with end. The companion format MetaPost (.mp) later extended Metafont's language for general vector graphics.
Metafont remains in active use because the Computer Modern and AMS typeface families - the default fonts of TeX and LaTeX - are distributed as .mf source. Editing requires knowledge of the Metafont language; any plain-text editor can open the files, though dedicated TeX editors such as TeXstudio provide syntax awareness.
Security & safety
RISK: LOWA Metafont .mf is plain text and contains no executable machine code, so reading it is safe. Compiling runs the trusted 'mf' interpreter from a TeX distribution. The only confusion risk is mistaking it for a JAR MANIFEST.MF; both are harmless text, but they belong to entirely different toolchains.
Format details
in a nutshell- Java/JAR MANIFEST.MF - Inside a JAR, META-INF/MANIFEST.MF is a plain-text manifest (Main-Class, versions) - the likely source of the DB's 'Sun Microsystems' developer tag.
- Maven / build metadata .mf - Some Java tooling and OSGi bundles ship manifest fragments with a .mf extension; plain text key:value pairs.
Programs that open MF files
Windows2 apps
MiKTeX (mf compiler)
Open-source Install MiKTeX, then run 'mf <file>.mf' (or 'mf \mode=localfont; input file') in a terminal to compile to .tfm/.gf. Read/edit the source in any text editor.
Text editor (Notepad++, VS Code)
Open-source Open the .mf to read or edit the Metafont source (it's plain text). Compiling still needs the 'mf' program. 
macOS2 apps
Text editor
Open-source Open the .mf to read/edit the source; use TextEdit (plain text mode) or any code editor.
MacTeX (mf compiler)
Open-source Install MacTeX, then run 'mf' in Terminal to compile the .mf. Edit the source in any editor. 
Linux2 apps
TeX Live (mf compiler)
Open-source Install texlive, then 'mf file.mf' compiles it to .tfm/.gf. Edit the source in any text editor. Technical details
deep spec| Format type | Plain-text Metafont-language source program; defines font glyphs as programs, not fixed outlines |
| Character encoding | ASCII; no multi-byte characters in the Metafont language itself; files open without conversion in any plain-text editor |
| Magic bytes / signature | None - no binary header; identified by the `.mf` extension and leading Metafont keywords such as `mode_setup;` |
| MIME type | `text/plain`; `application/x-metafont` used informally by some TeX tools |
| Compiler | `mf` program, invoked as `mf '\mode=localfont; input fontname'`; included in TeX Live, MiKTeX, and MacTeX |
| Compilation outputs | A `.tfm` metric file (character widths, heights, kerns for TeX) and a `.gf` or `.pk` bitmap at the chosen device resolution |
| Resolution / mode parameter | Target device and DPI chosen at compile time via a mode name (e.g., `ljfour` = 600 dpi LaserJet); changing the mode regenerates the bitmap |
| Parametric design model | Glyph shapes defined by pen strokes and numeric variables; adjusting one parameter (e.g., `stem#`) consistently rescales all dependent glyphs |
| Constraint solving | The Metafont interpreter solves systems of linear equations simultaneously to position points - shapes are stated as constraints, not absolute coordinates |
| Checksum pairing | The `mf` compiler embeds a checksum in the companion `.tfm` file binding it to the generated bitmap; the `.mf` source itself carries no checksum |
| Color support | Monochrome (1-bit) only - Metafont rasterizes glyphs as black-and-white bitmaps; no grayscale or color output |
| Typical file size | A few KB to tens of KB; a complete typeface family consists of dozens of `.mf` files sharing a common base file |
| Base macro library | Computer Modern uses `plain.mf` and `cm` base files; any `.mf` source may `input` shared macro files to inherit definitions |
| Active use case | Computer Modern and AMS typeface families (default TeX and LaTeX fonts) are distributed as `.mf` source and compiled on demand by TeX distributions |
| Successor format | MetaPost (`.mp`) extended the Metafont language to produce scalable PostScript/SVG vector output instead of bitmaps |
| Released | 1979 (Metafont); rewritten Metafont84 (1984) |
| Latest version | Metafont version 2.71828… (asymptotically approaching e; current since the 1990s) |
| Open standard | Yes · royalty-free |
| Specification | www.tug.org |
MF conversions
Community Q&A
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