Font licensing gets far less attention than image licensing, which is strange given how often text ends up printed directly on a product for sale. A font labeled "free" on a font marketplace or a free-font site is very often only free for personal projects — using it commercially, including printing it on a product you sell, frequently requires a separate paid license, even if the download itself cost nothing.
The confusion usually starts because free-font sites rarely make this distinction obvious at the download button. The actual license terms are often buried on a separate page or in a text file bundled with the font — and it's genuinely worth the two minutes to check, because font foundries do pursue commercial licensing violations, particularly against sellers who've printed the font on physical products at scale.
Here's the practical distinction to look for: "personal use" or "non-commercial" means you can use it for your own projects, mockups, or things you're not selling. "Commercial license," "commercial use allowed," or a specific paid commercial tier means you can use it in something you're selling — but even then, check whether that covers "print-on-demand" specifically, since some commercial licenses distinguish between a small print run and unlimited on-demand production, which is a meaningfully different use case to a font foundry.
A separate wrinkle: even with a properly licensed commercial font, most licenses prohibit distributing the font file itself — meaning you can use it to create a design and sell that design, but you can't bundle the font file into something you're selling (like an SVG file where the text remains editable and the font is embedded), unless the license specifically allows font embedding.
The safest practical habit: convert text to outlines/paths (sometimes called "create outlines" or "convert to curves" depending on the software) before finalizing a design file for sale. This turns the text into permanent vector shapes rather than live, editable font data — the visual design is unaffected, but the font file itself is no longer embedded or distributable, which sidesteps a whole category of licensing risk.
Reliable sources for genuinely free-for-commercial-use fonts include Google Fonts (nearly all fonts there are licensed for commercial use under the SIL Open Font License) and marketplaces that clearly state commercial terms upfront, like some options on Creative Fabrica. When in doubt, treat a font as personal-use-only until you've found explicit commercial language.