Wondaboo
Color by number, for children aged 4 to 10 — and a wizard that lets them invent a picture of their own, then colour it in.
What it is
Every picture is split into numbered areas. Tap a colour, tap the areas that carry its number, and an illustration appears. The outlines are drawn in ink and stay put, so a small hand cannot spoil a drawing by pressing in the wrong place.
The other half of the app is the making of new pictures: a child picks a subject, a place and a detail from illustrated cards, and a few seconds later has a colouring page nobody has ever coloured before.
For parents
No advertising. No account, no sign-up, and nothing that asks a child who they are. Every request for a new picture is checked for age-appropriateness before anything is drawn. What the app does collect, and why, is written out in plain language in the privacy policy.