I believe this is where the biggest difference lies. In Scrintal, each card is an entity of its own. You can think of cards similar to a page in Notion.

Once created, cards can be linked with other cards via links (similar to Obsidian), and each connection is visualized automatically on the whiteboard once the link is established.

This means the arrows between cards are actual links automatically drawn. This automatic way of connecting cards saves time when creating visual representations.

Heptabase doesn’t automatically show bidirectional links on boards but only allows you to manually draw arrows between cards without linking them. While this helps visualize connections on the surface, it doesn't establish the same structural relationships as Scrintal's automatic bidirectional links.

This is a difference in our approaches. I kind of like the idea of having the ability to draw “temporary” arrows because it can help in the very early stages of fast ideation.  In Scrintal, I also draw and remove the links in the graphs between cards with much more flexibility and liberty, but I must admit that when the ideation stage ends, and more specific work needs to be done, the backlinks inside the notes are really handy; especially to retrieve information later on when the cards are not on display. In Heptabase, although backlinks can be added within cards, they lack the visual representation seen in Scrintal's whiteboard view. This can be perceived as unnecessary friction, as users may find themselves needing to perform double work.

Since there is only one workspace where all cards are stored, you can bring a card to any board (i.e. project) you’re working on. This avoids duplication and enables reusing the same card across different projects in your knowledge base. Such design philosophy differs these tools from other online whiteboards such as Miro.

You create a card on the board where you see everything at a glance. You can open and write in multiple cards at the same time in one screen.