What Are Open Source Fonts and How Do You Use Them?

Open source fonts are typefaces released under a license that lets anyone use, study, modify, and redistribute them—including the font files themselves. You can use them in websites, apps, and print without paying a license fee, provided you follow the specific terms of the license (most commonly SIL OFL, Apache 2.0, or GPL). This guide explains the difference between open source, freeware, and public domain fonts, how the major licenses work, where to find and verify them, and the practical steps for embedding and attribution.

Open Source vs. Freeware vs. Public Domain

These three terms are often used interchangeably, but they mean different things:

• Open source fonts come with a license that grants the same freedoms as open source software. The license travels with the font, so derivatives must keep the same terms.
• Freeware fonts are free to download but the license may restrict modification, redistribution, or commercial use. "Free" here means zero cost, not freedom.
• Public domain fonts have no copyright restrictions at all. You can do anything with them, but the original designer gives up attribution rights.

The key practical difference: with open source fonts, you can legally modify the glyphs, rename the font, and ship it inside your product—as long as you comply with the license.

Common Open Font Licenses and What They Allow

SIL Open Font License (OFL)

The most widely used license for open source fonts (e.g., most Google Fonts). It allows:

• Use in commercial and non-commercial projects
• Modification and redistribution
• Embedding in websites, apps, and documents

Requirements:

• The font must not be sold by itself.
• Modified versions must not use the Reserved Font Name (if one is declared).
• Any derivative must also be released under the OFL.

Apache License 2.0

Used by some open fonts (e.g., early versions of Roboto). It allows:

• Commercial use, modification, distribution
• Patent grant from contributors

Requirements:

• You must include a copy of the license and state changes made.
• It does not have the "no selling by itself" restriction, but you still need to keep notices.

GNU General Public License (GPL)

Less common for fonts but used in some projects (e.g., GNU FreeFont). It allows:

• Use, modify, redistribute

Requirements:

• If you distribute a modified version, you must release the source under GPL.
• This can be problematic for embedding in proprietary software, because the copyleft may extend to the whole work depending on how it's linked. Many font projects use GPL with a font exception to clarify.

Rule of thumb: For most web and app projects, SIL OFL is the safest and most permissive choice. Apache 2.0 is also fine if you don't mind including notices. Avoid GPL fonts in closed-source products unless you understand the copyleft implications.

How to Find and Verify Open Source Fonts

Community libraries like Font Library (fontlibrary.org) collect fonts that are explicitly licensed for open use. When you download from such a library, the font page usually states the license.

To verify a font's license:

1. Check the font file itself. Open the font in a font editor (e.g., FontForge) or use a command-line tool like otfinfo or fc-query. The license is often embedded in the name table.
2. Look for a LICENSE or OFL.txt file in the download package.
3. Check the project's website or repository (e.g., GitHub). If the license is not stated, assume it's not open source.
4. Search the font name on a license database like the SPDX license list or the Google Fonts license page.

If you cannot find a clear license, do not use the font in a commercial project. "Free download" does not mean open source.

Practical Use: Websites, Apps, and Print

Embedding in websites

• Self-hosting: Download the font files (WOFF2 is best for web), place them in your project, and use @font-face in CSS. This gives you full control and avoids third-party requests.
• Third-party hosting: Google Fonts and similar services host open fonts and provide a CSS link. Check that the font's license allows this (OFL and Apache do).
• Attribution: OFL does not require attribution in the website's visible text, but you must keep the license file with the font files. Apache 2.0 requires you to include a NOTICE file if one exists.

Example @font-face for an OFL font:

@font-face {
  font-family: 'MyOpenFont';
  src: url('myopenfont.woff2') format('woff2');
  font-weight: 400;
  font-style: normal;
}

Embedding in apps

• Mobile apps: You can bundle OFL and Apache fonts in your app. For OFL, include the license text in your app's about screen or a licenses file. For Apache, include the license and any NOTICE.
• Desktop apps: Same rules apply. If you modify the font, you must rename it if the original has a Reserved Font Name.

Print

• You can use open source fonts in printed materials (books, posters, packaging) without restriction, as long as you don't sell the font itself.
• If you modify the font for a logo, check the license: OFL allows modification but requires the derivative to be under OFL. That means you cannot claim exclusive copyright on the modified font, but you can use it in a logo.

Common Licensing Mistakes and How to Avoid Them

• Assuming "free" means open source. Many free fonts are freeware with restrictive licenses. Always check the license file.
• Forgetting attribution for Apache fonts. Apache 2.0 requires you to keep copyright notices and state changes. Put them in a licenses file.
• Using GPL fonts in closed-source apps. The copyleft may require you to release your app's source. Use OFL or Apache instead.
• Selling a font you got for free. OFL and many other licenses prohibit selling the font by itself. You can sell a product that uses the font, but not the font files alone.
• Modifying a font with a Reserved Font Name. If the original font has a Reserved Font Name (e.g., "Roboto"), you must rename your modified version. Check the license for the RFN clause.
• Not including the license file when redistributing. Always bundle the original license text with the font files.

By following these guidelines, you can confidently use open source fonts in any project while staying compliant with their licenses.