As I write in every question about swimming pools... the only reliable source of information about swimming pools is on the website of the operator, Berliner Bäder(https://www.berlinerbaeder.de/), and nowhere else.
You can see on their booking site a summary of what has and will open in the near future.
But be aware that under the current circumstances you are basically playing a lottery with all of Berlin's swimmers.
The capacity of a two hours slot in Stadtbadt Mitte is thirty six people. By comparison Sommerbad Kreuzberg has 1112 places!
> Een website met koppeling richting zowel ticketsysteem als betaalsysteem bouwen en onderhouden is niet gratis.
Onderhouden allerminst, maar er zijn tegenwoordig prachtige oplossingen die je gratis (eigen beheer) of tegen een zeer redelijk bedrag (<2.5%) hosted en wel kunt afnemen.
En die crediteren de fees netjes als je (als organisator) een ticket cancelt...
Zou mooi zijn als meer partijen eens niet met Ticketmaster of Eventbrite in zee gaan.
Have a look at https://pretix.eu
It's completely opensource and performs great. Has an android and pc app for ticket-qrcode-scanning and tons of other useful features. We are using it for FrOSCon (https://www.froscon.de/) and it's also used at the Chaos Communication Congress (https://events.ccc.de/) and many other events by the german Chaos Computer Club and friends.
I am pretty shure https://Pretix.eu could handle this. It has contingents and add-on products. In case: you can try it out for free if your tickets are free. But it is also OpenSource and selfhostable.
Hey! I know tonight (02.10.) there is an "Unheilbar"-Party at Villa Nachttanz. It is a really nice-vibing-queer-party put up by nice people, everything not-for-profit. Tickets: https://pretix.eu/villanachttanz/UHB/ Unfortunately I don't know anything about dedicated queer cafés or something like that. Hope this helps!
Maybe Pretix could be of interest for you: https://pretix.eu/about/en/
It’s Open Source and for example used by the german Chaos Communications Congress. It supports scannable barcodes and has a POS app. Also supports plugins so if something is still missing it might be possible to extend it to match further requirements.
Maybe Attendize is what you're looking for. I haven't used it myself. There's also Pretix which allows you to self-host. First is written in PHP, second in Django (Python). Depending on your dev's knowledge, you might prefer one over the other.
Have a look at awesome-selfhosted repo for alternatives.