Digital Guitar Tuner is a free Windows software, which let's you accurately tune your guitar using direct input or microphone. Version 2.3, featuring 27 tuning types, is available for downloading. * High accuracy (uses 16 bit / 44100 Hz input!) * You can tune guitars with no signal output (through microphone) * 27 different tuning types (standard, lowered, dropped, open tunings, Hawaiian etc.) * Modulation of root frequency * Tuning with midi tones * Nice and simple environment * it's free!