Fontshare is a free font service launched by the Indian Type Foundry (ITF), a type foundry, that is, a company that designs and sells typefaces. It is a collection of professional fonts that are free for personal and commercial use. Part of the collection is ITF's own work, available only on Fontshare; the rest are open-source fonts from other publishers, which Fontshare reviews, fixes and republishes.
A designer picks a font family and its styles on the site. For a website, Fontshare gives a code snippet: a line for the HTML head and CSS rules that load the font files from Fontshare servers through the Fontshare API. The fonts can also be downloaded in OTF, WOFF and WOFF2 formats to install locally or to self-host with the CSS @font-face rule. ITF's own fonts are closed-source freeware under the ITF Free Font License (FFL); the others are under the SIL Open Font License (OFL).
The service is free of charge. ITF sells its other, commercial fonts separately.