If you roast your own coffee — on a popper, a SR540, a Behmor, a drum, or a cast-iron pan — the difference between a great cup and a flat one usually comes down to a handful of numbers you forgot to write down. RoastLog is a tiny, free, fully offline app that captures those numbers for every batch so each roast actually teaches you something.
Open the roast log →Roast weight loss is the single best at-home proxy for how far a roast developed. As beans shed moisture and organic mass, they lose weight — typically 12–18%. Light roasts land lower (often 11–14%), darker roasts higher. By logging green weight and roasted weight every time, you get a repeatable number to aim for instead of guessing by color and smell.
First crack is the audible milestone where roasting really begins to shape flavor. The stretch between first crack and drop — the development phase — is where acidity rounds out and sweetness builds. The development time ratio expresses that phase as a share of the total roast, and most roasters target somewhere around 20–25%.
RoastLog computes both weight loss and DTR automatically as you type, so you can compare a batch that tasted bright against one that tasted baked and actually see the difference in the data.
Everything is stored locally in your browser — no account, no cloud, no tracking. Pro adds CSV export, a sortable comparison table, and per-bean averages for nine dollars, one time.
Start logging your roasts →Related: Home coffee roast profile tracker · RoastLog app