Onramper's fee page is unusual because the headline is that there is no Onramper fee. The company says it does not add anything on top of the partner's rate, fetches live quotes from each on-ramp, and earns a referral fee from whichever partner fills the order. That is a fair model, and it means the number to look at is never Onramper's; it is the routed partner's. Across the network those partners charge card fees from roughly 1% to 5% or more, each with its own minimum, its own spread baked into the coin price, and its own network fee line.
In practice the widget shows several quotes side by side and highlights the best. Two things trip people up. The first is that the highlighted quote can change once the partner's own checkout loads and runs its verification, because the partner, not Onramper, sets the final price. The second is that Onramper may route a small order to a partner with lighter checks and a large one to a partner with a full ID flow, so the same customer can see different fees on different days. There is no withdrawal fee because Onramper never holds your coins.
Anytime Capital's card pricing starts from 4% with the spread included on card, Apple Pay and Google Pay orders, with the amount you pay and the crypto you receive shown before you confirm. On a $1,000 card order that is from $40, and it is the same number on the next order. At Onramper the number depends on the route, and what the widget cannot do is tell you the final figure before you start, or offer a wire or cash rail when the card is declined.