Every verdict on this site is an automated judgment built from two parts: label data from Open Food Facts, and a rule engine we wrote and keep tuning. You should know how both work, including where they fail.
The data
Open Food Facts is a nonprofit, crowdsourced database of packaged food, published under an open licence (ODbL). Volunteers photograph labels and transcribe ingredients. That model gives it a scale no company database matches, 28,601 of its products are in our checker right now, and it also means the data inherits human error: outdated photos, typos, missing nutrition tables. When the data is missing or ambiguous, our answer says so instead of papering over it.
The rules
Each diet is a fixed rule set, not an opinion. Ingredient lists are checked in the language they were written in, not just English, because a French label declares milk as "lait" and an English-only reading misses it. We learned that one from a reader. Keto is decided from the nutrition table, and missing macro data means we refuse to confirm anything. Halal distinguishes clear violations from Mushbooh, the doubtful additives whose origin a label cannot prove, and tells you which is which. The exact mechanics behind these checks are our own work in constant refinement, so we will spare you (and our competitors) the internals.
The bugs, in the open
Two recent ones, because a checker you cannot audit is just vibes. First, the French label problem above: before the fix, thousands of non-English products could show a wrong green; the correction changed more than five thousand verdicts in a single week. Second, a data import error briefly let an obviously sugary chocolate bar pass a keto check. We repaired every affected record and added safeguards so that class of error cannot slip through again.
What this means for you
Treat our verdicts as a fast, honest first pass, not a certificate. When we say yes, the label supports it. When we say no, we name the ingredient that decided it. When we say check the label, that is the truthful answer, and the page tells you exactly what is unverified. And when you catch us wrong, write to [email protected]. The best fixes in this engine started as reader emails.