Completing an online loan application is certainly convenient, but make sure you know where and how often your information will be used. If you apply for a loan or other services at a specific financial institution, that institution will be the only party privy to your information. But if you apply for services at a site that will then distribute your information to a number of different parties, you not only lose some control over your information but you also may find that multiple parties will access your credit report.
Say, for example, that you fill out one online application with a firm that will then solicit offers from a number of financial institutions. Each institution will review your information and each institution may pull a credit report. The firm soliciting "bids" from other financial institutions will certainly try to maintain your privacy and confidentiality, but you may not wish to take that risk. (Plus, multiple credit inquiries could negatively impact your credit score.)
When you apply online, know how your information will be used.