Stamps.com offers an online service in which you can digitally apply postage to an envelope. They even include a nifty/free digital scale to attach to your computer.
The problem of course is that in order to make back the cost of that “free” device, Stamps.com wants to charge you on a monthly basis to use this service and most people decide that it’s not worth those charges. I often see these sitting idly on someone’s desk and it’s only useful for measuring the weight of something. Without their service, you’d then need to manually lookup the postage and then count the right number and types of stamps.
I’ve written a Windows program which will do all that for you, weighing the envelope, calculating the postage and letting you know how many stamps of which kind to put on it.
Here is the new repository on github.com. You can run it directly or build the program yourself if you have a copy of Visual Studio, to include the free Community version. Your computer will need the .NET Framework 4.5.2, for what it’s worth.