Find out which notes you're actually off-key on.

When a developer posted OnKey on Hacker News with the line "I'm a bad singer, so I built an app to show where I'm off-key," the thread hit 214 points and drew 89 comments. Almost nobody argued about the algorithm. Instead, people asked the same two things: can I see my own pitch curve, and can I compare it to the original singer? That reaction is the signal. Hundreds of people wanted to measure themselves, not to learn music theory, and they wanted the result to be something they could look at and show someone else.

The tools that exist today do not answer that demand well. Vocal Pitch Monitor is accurate but looks like a 2012 Android utility and interrupts you with ads. Sing Sharp and Vanido are subscription apps built around daily practice routines, which is a different job than "test me once and tell me the truth." Yousician gamifies learning at nineteen dollars a month. None of them treat a pitch result as a small, shareable object. They treat singing as a curriculum, and most people who are curious about their own voice do not want a curriculum. They want a mirror.

That gap is why the timing works. Browser audio is finally good enough: the Web Audio API and lightweight pitch detection libraries like pitchy run entirely on the client, so a recording never leaves the device and no backend is required. That means we can ship a real tool in a weekend, keep it free to try, and test whether people actually want to share their score or gift a pitch check to a friend. If the share card travels, the product has a business. If it does not, we learned that cheaply.