These two get compared because they attract the same person: someone doing serious reading who wants their notes to add up to an understanding rather than a pile. They answer that want very differently. Heptabase gives you an infinite whiteboard and asks you to arrange your thinking in space. Obsidian gives you a folder of markdown files and asks you to link it. (Disclosure: we make a third app, Clair Mind, which does neither of those things and is not in this race. Referee only.)
At a glance
| Heptabase | Obsidian | |
|---|---|---|
| Core unit | A card, placed on a whiteboard | A markdown file in a folder |
| Primary view | Infinite 2D canvas | Editor plus links and graph |
| Storage | Its own sync layer, with local data and offline use | Plain .md files on your disk |
| Price | Paid subscription, around $11.99/month or roughly $8.99/month billed annually | Free for personal use; paid Sync and Publish are optional |
| Extensibility | Limited, by design | Very large plugin ecosystem |
| PDF workflow | Strong: annotate, and pull highlights onto the board | Workable via plugins |
| Learning curve | Low, the canvas explains itself | Medium, and higher if you add plugins |
| Best at | Making sense of something new | Keeping and connecting notes for years |
Pricing changes; check both sites.
What Heptabase is actually for
The pitch is spatial. You read a paper, make cards for the ideas in it, drag them onto a whiteboard, group them, and draw arrows. The board becomes an explicit picture of how the pieces relate, and you can zoom out and see the structure of an argument you are still building.
The reason this works is not mysterious. Position and grouping give you a second encoding route alongside the words, which is the same effect described in dual coding, and physically moving a card is a lower-effort way to express a relationship than deciding what to name a link. For literature reviews, research synthesis, and the early stage of a book or thesis, this is genuinely better than a list of files.
The cards are real notes underneath, with markdown, backlinks and tags, so it is not a diagramming tool with text glued on. It also handles PDFs unusually well: annotate in the app, and pull your highlights out as cards you can arrange. If your work is reading papers, that pipeline is the strongest argument in its favour.
What Obsidian is actually for
The pitch is ownership and longevity. Your notes are markdown files in a folder on your machine. You can back them up, search them with anything, put them under version control, and open them in twenty years with software that has not been written yet.
Around that sits a large plugin ecosystem and a mature linking model: [[wikilinks]], backlinks, and a graph view. It is the natural home for a Zettelkasten, and the default recommendation for anyone who wants plain text notes that outlive the app.
Obsidian also has Canvas, an infinite board where you place notes and draw connections. It is worth trying before you pay for anything, because for some people it covers enough of Heptabase's appeal. It is not as polished, the card-to-board workflow is clunkier, and it is not the centre of the product the way Heptabase's board is. But it is free and it is right there.
The honest trade
The cost of Heptabase is dependency. Your thinking lives in a proprietary structure, and a whiteboard is much harder to export meaningfully than a note. You can get your text out, but the arrangement, the arrows and the groupings are the value you created, and that value is the hardest part to take with you. On a subscription, that is a compounding commitment. Ask the export question early.
The cost of Obsidian is assembly. It ships as a workbench. Getting to a comfortable setup involves choosing plugins, deciding on a folder scheme, and resisting the urge to spend three weekends configuring rather than writing. A meaningful number of people never get past that stage, which is a real failure mode and the most common entry in PKM mistakes.
Both share a quieter cost: they are desktop-first tools for sitting down and doing deliberate work. Neither is good at catching a thought in eight seconds while you are walking.
Choose Heptabase if
- You are synthesising a body of reading, a thesis, a literature review, a report, and you need to see how the pieces relate.
- You work heavily with PDFs and want highlights to become manipulable objects.
- You have tried outline-shaped tools and found that lists flatten the relationships you care about.
- You would rather pay a subscription than spend evenings configuring software.
Choose Obsidian if
- You are building something you intend to keep for a decade or more.
- File ownership matters to you, whether for privacy, backup, or principle.
- Your notes are mostly prose and links rather than spatial arrangements.
- You want it to be free, and you are comfortable assembling your own setup.
For most people writing notes over years rather than synthesising one large project, Obsidian is the safer default, and its Canvas gives you a version of the other thing at no extra cost. Heptabase wins decisively when the project is a mess of sources that needs a shape, and you are willing to rent the place where the shape lives.
The situation neither of them fits
Both assume the hard part is arranging what you have collected. For a lot of people the hard part is earlier: the thought arrives at a bus stop and never reaches any app at all. If your notes app is open once a week at a desk, no amount of canvas or graph will help, because nothing is going in.
That is the problem Clair Mind is built for: one-tap capture on the phone, offline and private, with connections drawn for you instead of maintained by hand. It is not a research canvas and it will not replace a vault for someone writing a thesis. Different bottleneck, different tool.
Related comparisons: Obsidian vs Logseq, Notion vs Obsidian, and the wider note app comparisons.