Frequently asked questions

A visual taxon-identification game. Each round shows two photos and two names drawn from a matched pair of taxa; you drag each name onto the photo it belongs to. It's built to train the same pattern-recognition naturalists develop over years in the field, just compressed into short, repeatable rounds.

Everything traces back to iNaturalist — real observations submitted and identified by its community. Taxonomy, vernacular names, geographic range, and photos are all sourced from there.

Every pair carries a visual-similarity level, so a session can start easy — taxa that don't really resemble each other — and step up toward genuinely confusable look-alikes. You can also filter by taxonomic group, tag, geographic range, or difficulty, or follow a shared link straight to a specific pair.

Yes — DuoNat is free to play, in the browser or as an installable app. It's a labor of love — around 2,000 hours of work so far — but it isn't free to run, and we still need to eat. Servers, storage, and data all cost money, so DuoNat depends on donations to keep going. We don't run ads and we don't sell your data — so if you can, please consider chipping in.

Not a native one yet — publishing to the App Store requires a Mac to build and sign the app, and we don't have one. In the meantime, DuoNat runs well as a web app in Safari: open it, tap Share, then "Add to Home Screen" for a full-screen, app-like experience. If something doesn't behave well on iOS, tell us and we'll do our best to fix it — and if you'd like to speed up a native app arriving, a donated iPhone and/or MacBook is the most direct way to help. 😄

No — you can play right away. But without an account your progress and streak live only in this browser, so they can disappear if the browser clears its storage. Signing in saves them to your account and lets them follow you across devices.

Coverage spans the tree of life and keeps growing. The stats page shows exactly which clades are represented right now, and how well each is covered across continents.

Sort of — but you'd be learning a folk category, not a branch of the tree. Butterflies and moths are all Lepidoptera, and "butterflies" are one superfamily inside it (Papilionoidea, roughly 19,000 of some 160,000 described species). "Moths" is all the rest — around nine species in ten — held together not by anything they share, but by not being butterflies.

The rules of thumb leak, too. Clubbed antennae? Skippers end in a hook, and burnet moths have perfectly good clubs. Flies at night? Plenty of moths are out in full sun. Drab? Tell that to a luna moth. And the split is mostly an English habit — in French a papillon is both, and German divides them into Tagfalter and Nachtfalter, day flyers and night flyers, keeping Motte for the small ones in the wardrobe.

Which is a long way of saying: DuoNat filters by clade instead. Pick Papilionoidea and you get butterflies; pick Lepidoptera and you get the lot — and either way you're comparing species grouped the way they're actually related. You know, the science way :)

Every photo's info dialog in the app links back to its source observation on iNaturalist, and includes a report option — that feedback goes directly into a review queue.

Email portioid@gmail.com — for feedback, bug reports, ideas, or just to say hello. You can also reach us on our Discord.