If you do not have your child every day, the details of their life end up scattered. A bedtime routine in one text. An allergy in an email you never deleted. A teacher's name you are sure somebody told you once.
Little Green Book is somewhere to keep all of it, so you walk into your time together already prepared.
It works completely on its own. Nothing in it needs the other parent to join, or to agree, or to do anything at all.
Daily routines, health and allergies, school, doctor and contacts, friends, and the clubs and activities they go to. In your words, in one place, ready the moment you need them.
Set the days you usually have them, once, and the diary fills itself in. The same days each week, a week on and a week off, or two nights, two nights and a long weekend. Change a single weekend without touching the arrangement behind it. Mark a day they are not coming, say why, and it stays on the calendar with the reason under it. See the week along the top, or open it out into the month, with the school holidays and bank holidays on it.
The days you have had them, the days you missed and why, the changes to your usual days, and the year month by month. One tap on a day that has passed says whether they were really with you, so the figures are a record rather than a guess. Every number says what it counts and the date it counts from.
A widget that says when you next have them and what is planned, so you can see it without opening anything.
A reminder the night before you have them, with whatever is still unpacked. Set by your phone, on your phone, with no account and nothing sent anywhere. You can also keep a standing time to speak on the days they are not with you: the app remembers when you agreed and opens FaceTime or the phone, and it never carries the call.
A month on one page, to send or print for a grandparent picking up, a childminder, or a solicitor. They need no account and nothing to join.
A hundred and thirty-two things to do with a child, from a wet Tuesday afternoon to a proper day out, and somewhere to turn one of them into a real plan with a date on it.
Your own photographs and a few lines about the day. Private, and yours.
You can suggest a change, ask about a pickup, or pass on something practical. Nothing changes an arrangement until it is accepted, and ignoring a message leaves everything exactly as it was. Neither of you is in charge of the other, and neither of you is the guest.
Your memories, your plans and your private notes are never part of it. There is deliberately no button to share a memory.
There is no account, no sign-up, and no server of mine. Nothing you write is sent anywhere, because there is nowhere for it to go. The app's only internet request is a daily look at its own App Store page to see whether an update is waiting, and that request says nothing about you.
When you do send something to the other parent, it goes as a small file through the sharing you already use: a text message, AirDrop, email. Your choice, every time, and still nobody's server in the middle.
You can keep the book shut behind Face ID or a PIN. You can save a backup file and keep it wherever you keep things. You can erase everything, properly, whenever you like.
Written in Britain, for parents here. Dates read the way you write them, and the things to do include the ones that only happen here.
One payment. There is no subscription, no free trial that turns into one, and nothing held back to unlock later.