System Architechture

Homework-Buddy consists of several webapps (or "websites"):

1. Main website: It is planned to be built on top of the popular WordPress CMS to deliver the website quickly and reliably. Read more.
2. Parents' Corner: The specific web app buily for parents, where they can register and monitor their child(ren) as Homework-Buddy students. Read more.
3. Students' App: The heart of Homework-Buddy system itself - it will be used by students to manage and do their assignments., timetable, and so on. Read more.
4. Backoffice: It is a specific web app for operating Homework-Buddy system by the in-house team, both admin and staff (lesser privileges). Read more.

Infrastructure & Third Party Services

1. Virtual Private Server (VPS): https://www.hetzner.com/cloud/cost-optimized 
   1. VPS #1 (CX33 - Linux) will be used as application server, at least 8GB of RAM is recommended since it will be a monolith for starter (app, database, caches, web server, etc are in single server instance.
   2. VPS #2 (CX23 - Linux) will be used to host the main website only, and requires slightly lower specs since WordPress can run even with 2 GB of RAM. Here we recommend 4GB for future-proofing. 
2. S3-compatible Object Storage: https://www.hetzner.com/storage/object-storage/ - a 1TB storage with 1TB bandwidth is recommended for starter. The object storage server is used for storing assets (uploaded media files) so it does not burden the application server's (storage and bandwidth), also better deliverabilites and scaling strategy (if needed in the future).
3. Transactional email service: https://www.brevo.com/pricing/ for transactional email service, to send lot of emails without getting blocked / flagged. 5,000 or 10,000 emails per month plan is a good starter.
4. Payment gateway: a popular choice is https://stripe.com/, with the processing fee illustration as follows:
   

   EU cards (Visa/Mastercard)	1,5% + €0,25 per transaction
   Non-EU cards (e.g. US, Asia)	3,25% + €0,25 per transaction
   SEPA Direct Debit	0,35% (€6 max)
   iDEAL, Bancontact, dll	0,8%(€5 max)

   Then if we use Stripe's automatic subscription (recurring billing) feature - which is helpful to not implement automatic subscription feature by our own, then the processing fee cost above + 0.5% (per transaction).