Most professional keyboards have onboard tuning, I have a Kurzweil PC-88 controller that I use as my main keyboard that controls other sound modules, this one can be tuned through the display panel, very easy, and I always check the tuning before I record and make sure is is to A-440. If your keyboard is a home use digital piano, this feature may be a factory fix, But Kurzweil keyboards usually have onboard tuning. I recently had my Vibrandoneon serviced and I had them tune it to A-440. In an accordion, they sometimes tune them a bit higher because the bellows can push a lot of air at once if needed and will detune some notes, but again the melodica is not an accordion. I have to agree with Kevin, that if you walk into a session whip out your melodica and are out of tune with the other musician and can’t adjust your tuning, you are going to loose a lot of credibility pretty quick. You have to know how your instrument works best and practice dynamics. also a 99 cent apps for your I-pad or I-phone are not going to be as accurate as a regular chromatic tuner. Invest in a decent one if you are going to tune your melodicas by yourself.