Session / Topline
Load a Creative-Commons instrumental — a ccMixter track works well — sing or write your melody and words over it, then listen back to your take with the track underneath. Everything happens locally in this page; nothing is uploaded anywhere. Browse tracks at ccmixter.org.
Open a track's ccMixter page → use its "Download" link (the direct .mp3 URL), not the page URL itself.
Microphone not yet enabled. Headphones are strongly recommended once you record, so the track doesn't bleed into the take.
Plays the track and your selected take together from the top. They're two separate players started together, so on very long takes they may drift a second or two — use Stop and Play mix again to resync.