Not a typeface format but a wrapper: a TrueType or OpenType font compressed for the web, typically 40% smaller, and what @font-face expects. The outlines inside are untouched, so unwrapping one gives back exactly the font that went in.

Every conversion below runs in this page, on your own machine. Nothing is uploaded, there is no queue, and there is no account to make. Pick a target format, or just drop a WOFF file above and choose afterwards.