What is local-first software?
In a cloud-firstapp, the real copy of your data lives on a company's servers; your device just shows a window into it. Close the connection and the app stalls. In a local-first app, the canonical copy lives on your device, and the cloud is a sync layer rather than the source of truth.
The magic that makes this practical is CRDTs— conflict-free replicated data types. They let every device hold a full copy and merge changes automatically, so two devices editing the same thing offline won't clobber each other when they reconnect. It's the same family of tech behind real-time tools like Figma and Google Docs, applied to private, offline-capable apps. (We go deeper in how offline-first sync works.)
Why local-first matters
Privacy & ownership
Your data lives on your device first, not on someone else's server by default. There's nothing to mine, sell, or leak.
Works offline
Read, write, and search with no connection. Planes, basements, bad Wi-Fi — your workspace keeps working.
Instant & reliable
Local reads and writes feel instant because they don't round-trip to a server. No spinners, no 'connection lost'.
No lock-in
Open formats and export mean you can always take your data and leave. The app is a tool, not a hostage situation.
Local-first vs cloud-only
| Dimension | Local-first | Cloud-only |
|---|---|---|
| Where your data lives | On your device first, synced | On the provider's servers |
| Works offline | Yes — fully | Usually no, or read-only |
| Speed | Instant (local reads/writes) | Depends on the network |
| Privacy | Private by default | Trust the provider |
| If the service shuts down | You still have your data | Access can disappear |
| Lock-in | Low — open formats & export | Often high |
Cloud-only isn't evil — it's great for real-time collaboration and zero-setup access. The point isn't “never use the cloud.” It's that for your personalknowledge — notes, bookmarks, files — local-first gives you reliability and ownership that rented servers can't.
How to choose a local-first app
- Stores your data locally and works fully offline
- Syncs across devices without overwriting your edits (look for CRDTs)
- Uses open formats — Markdown, HTML, JSON — so export is painless
- Lets you leave: one-click export and no proprietary cage
- Is private by default, with no ads or data selling
Local-first for notes, bookmarks & files
Most local-first tools specialize. Obsidian is excellent for notes as plain-text Markdown files. But bookmarks and files usually end up in separate apps, and syncing across devices is often a paid add-on.
StashSynctakes the local-first approach and applies it to all three — notes, bookmarks, and files — in one offline-first workspace, with cross-device sync and public sharing included. If you're weighing the options, see how it stacks up as an Obsidian alternative, or, if you build things, what's possible with its API and MCP server.