Astuto : Astuto is a free, open source, self-hosted customer feedback tool. It helps you collect, manage and prioritize feedback from your users.
Novu : The open-source notifications infrastructure. A fully-featured microservice to send SMS, E-mail, Slack and Push notifications. Embeddable notification...
Kinto : Kinto is a lightweight JSON storage service with synchronisation and sharing abilities.
Keycloak : Keycloak is an Open Source Identity and Access Management solution for modern Applications and Services.
SimpleLogin : With email aliases , you can be anonymous online and protect your inbox against spams and phishing. Open-source.
Open source meeting scheduling tool. Send a link, let others book a slot. Calendly alternative.