Bless the developer for creating this app! Samurai Search is terrific. It's very intuitive. You add a search folder and then put in your search parameters. It's supports every text format you can think about as well as PDFs. You can also add your own text extensions if you want. For power users, it supports Regex, file filters, and so on. It ripped through a multi megabyte list of hundreds of json files immediately. The search terms were highlighted in each indicated file. You can export that list. It's a huge time saver if you are working on an iPad or iPhone.Sure, there are tons of websites that will do this. You could also run a terminal app. However, Samurai Search makes it easy and keeps your local searches local. Finally, it is truly free. No cripple-ware, no ads, no registration required. Still, if I had to pay a reasonable fee for this app, I absolutely would. Thumbs up!