Can anyone recommend a really simple shared calendar app which me and a group of friends can use to arrange get-togethers? At the moment we use a WhatsApp group and all the "I can do this date but not that", "oh sorry I forgot it's MIL's birthday/the cat's jabs/my hysterectomy" (OK maybe not that) messages flying backwards and forwards are driving me mad. Some are Apple and some Android so it needs to work for both. Thanks