I had the idea of making a website where anyone of a group of friends can post their evening plans - go to trivia, play tennis, etc - and others would be able to sign up to join.
Never made it but glad to see these things can work.
This was the original purpose of Twitter-- it was advertised as a network where anyone could post what they're doing and notify their friends immediately. Even until recently tweets could be received via SMS (not sure about the current status of that feature) so you'd see in real time what they're up to.
Of course, Twitter/X/etc are a far cry from that now-- but it could be worth trying where you and your friends use the service like that.
I do think this is an interesting idea. Lemme see if I can do this. How do you think the UI/UX should look like.
Here's what I am thinking.
You sign in
It asks you what you want to do
And at what time (hour) in another column and (date) in another column
And then it asks you the location
And then we can have a contact-me: which could lead to discord or signal. Or, if you aren't comfortable sharing that info, then you could have a shareable link that you can share with anyone and then they can write their email or whatever and you would get live notifications through mail or whatever platform you decided.
Lemme know if we are on the same page?
EDIT: I have created a mvp but like, the problem is that it's just a form y'know and I just created something where you would input in this information and it would give html and then you can host it and using https://formsubmit.co/ you can use it. Though I guess one of the issues is that you have to validate each form in formsubmit (not good for ephemeral forms) and I guess it also shows email but there's a way to hide it too.
Also, I guess the problems aren't of forms but of discoverability. How do you make people discover your forms but I guess one way could be of having a list of all your forms or just the current ones that you want to show (IDK?) on github pages for example and then you could just share the github pages link to anyone or just have it in a about me section of most messengers?
Also.. Maybe then if you wanted to rather share it to anybody you could create a additional place where anybody can share their forms/such website. But I am not sure if what I've all said is the best user experience.
The UI I envisioned is that the website shows what people are doing and when. You can add activities (with a form like you descibed) - but the key is that a site will show what's going on right now and for the rest of the day. And when people add to that site, notifications go out.
use a kanban board. FOSS options exist for web-hosted implementations. Kanban works because It supports a 'backlog' of events to do, timelines for things to do that are on a deadline (e.g. concerts) and allows people to add activities / plans to backlogs which get moved to 'ready to do' as things are done / cleared. Keeps everything organised and simple, with good over-sight on what's going on when. Downside is it requires friends already somewhat technical or at least willing to learn.
Never made it but glad to see these things can work.