iZotope has released Vocal Doubler, a free effect plugin designed to enhance vocals with a natural doubling effect, adding rich tone and depth.
You can control the doubled effect directly through an interactive visualization. With drag up and down you increase or decrease the stereo separation. If you pull left or right, it adds a natural human-like variation to the signal.
Vocal Doubler is perfect for placing directly on your vocal track and just adding a touch of space to make it stand out in the mix. Using “Effect Only” mode, you can also create multiple doubled vocals on different tracks to further customize your sound.
iZotope Vocal Doubler is available for Windows and macOS (VST2/VST3, AAX, AU). In order to download it, a (free) iZotope account is required.
More info at iZotope.