diagrams.net (previously draw.io) is a free online diagram drawing application for workflow, BPM, org charts, UML, ER, network diagrams. No login or registration are required and features include the ability to save locally (including SVG), a range of stencils, .
diagrams.net vs Miro opinions
not a whiteboard app to collaborate online, but a diagram drawing tool
While it isn't the same as Miro (and tbh no other tool comes as close to what Miro does so far) but it's a good "start" which is fully free. Collaboration via Google Drive/Workspace works fine, but again not a proper Miro replacement but the best we got so far.
Not an online real-time collaborative white board.
Miro is a whiteboard app for online collaboration, while diagrams.net is just a diagram drawing app
Excalidraw is an open-source whiteboard tool that lets you easily sketch diagrams that have a hand-drawn feel to them. Available directly online as a web app and also through CodeSandbox to easily see how the code works, and the app is available for self-hosting.
Excalidraw vs Miro opinions
Click and play : Simple and encrypted.
Also, it is open-source and can be installed on your server.
No membership needed to collaborate on a diagram. Very easy to use. Unfortunately doesn't work with Fireforx 90.0.1.
Open source, free, end-to-end encrypted. Libraries of shapes to import.
scrumblr - Collaborative Online Scrum (whiteboard + kanban) Tool Using Websockets, Node.js, jQuery, and CSS3
scrumblr vs Miro opinions
if you just need an intuitive app to collaboratively arrange columns and cards on a whiteboard, this analogue-feeling open source tool might come in handy. no accounts needed.
Mindmapping made simple: Host and create your own mindmaps. Share your mindmap sessions with your team and collaborate on mindmaps.
Collaboration + Whiteboard = Collaboard.
Sketch your projects and your dreams on an unlimited online whiteboard. With Collaboard “Great Minds Think Together”.
Virtual classroom even for elementary school students. Video chat and whiteboard. Real time interaction. Anonymous, secure and privacy-friendly. No login required. Free and open source.
WBO is an online collaborative whiteboard that allows many users to draw simultaneously on a large virtual board. The board is updated in real time for all connected users, and its state is always persisted.
whitebophir vs Miro opinions
currently the only viable open source collaborative whiteboard tool – if you don't need something as advanced as miro.
lack of features... mindmaping, etc.