There are a few 555 timer design software applications that will help you in your projects. Component value calculations for the 555 take into account the supply voltage, timer fabrication (CMOS or Bipolar), and, where appropriate, load currents.
Free 555 Timer software for Windows allows you to calculate Resistor and Capacitor values for both Astable and Monostable modes. It works with Windows Vista but I could not use it on Windows 7, it gives an error “Can’t load (or register) custom control: ‘COMCTL32.OCX’. Maybe the programmer Andy Clarkson will give us a feedback 😉
If you know some other 555 software please write a comment with the link. Thank you and I hope this will help you.