Swapfig is and has always been free to use, and is supported through advertising. However, a lot of hours, energy and dedication went into the creation and maintenance of the site.
If Swapfig has been useful for you at all, please consider making a donation. It doesn't have to be an equivalent salary; we appreciate any amount you're able and willing to donate.
Your donations will go toward the site's development and running costs, and the occasional cup of coffee.