So the program is free and it's called SharpKeys. It's been around for ages and it's safe. It was not created for Runescape purposes so I doubt that they want your pass.
The thing you should know though is that that this DOES NOT swap your keys out for others, it BINDS one to the other. So if you change your F5 (which I believe is the Prayer Book hotkey in OSRS) to F3, then your F5 will no longer refresh the page, F3 will.
HOW TO CHANGE OSRS BINDS TO WHATEVER YOU WANT
- Download Sharpkeys here http://sharpkeys.en.softonic.com/
- Open the program, hit "add" http://prntscr.com/2k0rwx
- Then click "type key" on the left side. This will be the key that you want to bind the other key to. So if you want to press "F2" and have it be bound to your Inventory, you'd press F2 on this side. http://prntscr.com/2k0svo
- Next you need to choose what key you want to bind to the first key to. Click "type key" on the right side. So if you want F2 to be your inventory , you'd press "Esc" here. http://prntscr.com/2k0tpr
- So you do that to all the keys you wish to change. Just remember the first key will be the key you wish to press and the second is the key that you currently press for whatever you want. (mine will be different because I use a Naga mouse.)
- Then all you need to do is press "write to registry" http://prntscr.com/2k0udh and then restart you computer.
- If at any point you want to delete them you simply click "delete all" then "write to registry" and restart your computer and everything will be the same way it was.