Electronic System for Travel Authorization
Please note that there is only one official website for the US Embassy and your requirements about ESTA: https://esta.cbp.dhs.gov/esta/
The official rate to obtain an ESTA is 14,- USD.
ESTA is an electronic registration system requiring travelers who are part of the Visa Waiver Program (VWP) – 27 countries including Belgium – to register before boarding a plane or cruise ship destined for the United States.
The ESTA program entered into force as of January 12, 2009. Registration may be done by third parties (travel agencies, family, friends). As of 8 September 2010 ESTA is no longer free. The total fee for a new or renewed ESTA will be $14.00. All payments for electronic travel authorization applications must be made by credit card or debit card when applying for or renewing an ESTA at https://esta.cbp.dhs.gov. The ESTA system currently accepts only the following credit/debit cards: MasterCard, VISA, American Express, and Discover. Your application will not be submitted for processing until all payment information is received.
Registration should preferably be done 72 hours prior to the beginning of a trip but it is in principle possible to register at any moment before departure. A last minute departure for the United States will always be possible.
Registration is valid for 2 years and for multiple entries. It is possible to bring your data up-to-date at any time. An answer will be given immediately in the majority of cases. The person who does not receive authorization will need to go to an embassy or a consulate to apply for a visa. The ESTA authorization does not mean moreover that access to the United States is guaranteed.
The ESTA program does not apply to Belgians who are holders of a visa for the United States. Registration should be done on the following site: esta.cbp.dhs.gov.