lol This is the exact same question I had when I first started using Ebay a long time ago. Does it ever say you are the top bidder and then say you were Outbid? Or does it just go straight to "You were outbid?"
If you aren't familiar with how Ebay works (which is fine), it works like this: When someone puts in their max bid, they don't pay their max bid, they have to pay whatever the next highest bid is. For example, if you bid on a pin $1,000. The next highest bidder who got second place only bid $100. You would only have to pay $100.50 (right about their bid). So, if you bid on an item and it immediately says you were outbid, that isn't because someone else is using an app or is sitting there outbidding you, it is because you just didn't beat their max bid. Once you beat their max bid you will remain the top bidder until someone outbids you.
As Pin-A-Colada said, there are apps for Ebay auctions but in all my years (about 8 years) of using Ebay I have never been put up against one because people are very skeptical on using them. If a person really wanted a pin bad enough to pay anything for it, instead of using an app, they would just bid $999,999.000 on it. Then, unless someone else bid 1 million dollars on it, the person would win regardless. Apps aren't necessary for Ebay if you really want something lol xP