Be wary of Unofficial Websites.
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Official ESTA Website - Applications
Official US Government - FAQ’s
I’m a member of a consumer organisation and feedback from them points out there are unofficial sites – here for example - with similar names to the official site, who charge a fee which is unnecessary.
Not only are you charged a fee but there is the down side of providing them with your personal details which can have a down side.
Therefore just to emphasis, the ESTA process itself is free and comprehensively explained by the US government on its website which should be consumers’ first port of call.’