Vellum and Obsidian.
Both keep Markdown with [[wikilinks]], backlinks, tags and a graph, on your own device. Obsidian is a notes app with a large plugin ecosystem; Vellum is a workspace with code, files and a private assistant built in. They also differ in where your writing lives.
At a glance
| Vellum | Obsidian | |
|---|---|---|
| App | A web app: open a page, install it if you like | Desktop and mobile apps |
| Where your writing lives | The browser’s private storage on your device | Markdown files in a folder you choose |
| Format | Markdown, exportable as an Obsidian-compatible .zip | Markdown files |
| Links, tags, graph | Yes: [[wikilinks]], embeds, backlinks, tags, graph | Yes |
| Running code | Built in: 25 languages, outputs saved with the page | Through community plugins |
| AI | Built in, optional, on the device, with citations | Through community plugins |
| Files | PDFs, documents, media viewers; search inside them, OCR opt-in | PDFs, images and media; more through plugins |
| Sync | Free, end-to-end encrypted: through your own synced folder, or device to device after pairing by QR code | Obsidian Sync (paid, end-to-end encrypted) or any file sync |
| Extensibility | No plugins | A large plugin and theme ecosystem |
| Cost | Free, no account | Free; Sync and Publish are paid add-ons |
When to choose which
Choose Obsidian if you want your notes as files on disk that any editor can open, native mobile apps, or the plugin ecosystem.
Choose Vellum if you want code, charts, document viewers and a private assistant built in, nothing to install, and free encrypted sync.
Moving between them is easy: Vellum imports a vault (folders, links, embeds, frontmatter, attachments) and exports an Obsidian-compatible .zip.