Cloud storage decision

Obsidian Sync

A small team or engineer can build a basic encrypted file-sync service for Markdown vaults, but reproducing Obsidian Sync’s polished UI, tight app integration, and collaboration experience requires substantially more work and ongoing product polish.

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You pay

$5/mo

$60/yr

Per seat. Read off the official pricing page.

You’d pay instead

$100one-off80 h to build

$30/mo8 h/mo upkeep

On cash alone, building overtakes the subscription at 8 seats.

Open-source builds that already do this

Every project below is open source and already does this job today. Fork one, self-host it, or take the parts you need - the build prompt further down assumes an empty file, and this is the shortcut past that. Licences differ; check the one on each card before you ship. All Obsidian Sync alternatives, with the arithmetic →

What a replacement has to do

  • Keep a Markdown vault in sync between devices with client-side encryption and per-file version history + basic sharing of vaults.

What it still won’t have

  • Tight integration with Obsidian desktop/mobile app and plugin ecosystem
  • Official selective-sync UI and per-file preference controls
  • Obsidian-hosted version history UI and priority support
  • Polish around shared vault invitations and collaboration workflow

What remains hard

  • Product polish and ongoing maintenance
Read the build prompt

First-year cost

Keep paying

Paying is—cheaper in year one.

On cash alone, building overtakes the subscription at 8 seats.

Paid seatsseats

Money you would actually spend

Keep paying
—

Subscription price × seats × 12

Build it
—

AI build —APIs + hosting —

Time you would spend

—

—

What you would spend

What we assumed

The verdict above measures whether you could build it. This one is only about money.

Runnable build prompt

Not run yet
Build a minimal Obsidian-compatible sync service using Node.js (Electron clients can be omitted): 1) implement a cross-platform file watcher and CLI client in Node that uploads changed Markdown files to an S3-compatible backend; 2) implement client-side AES‑256 encryption of file contents and metadata before upload and decryption on download; 3) store each upload as an immutable blob and record version metadata in Postgres; 4) implement a small HTTP API (Express) to list vault files, versions, and to fetch blobs; 5) implement a simple email-invite based shared-vault ACL in the API; 6) provide conflict detection and a basic web UI to view/restore versions and resolve conflicts. Out of scope: mobile native apps, plugin integrations, rich selective-sync UI, and an Obsidian plugin — but design the API so an Obsidian plugin could be written later. Include error handling, input validation, and unit tests for core modules.
How we checked4 sources · 3/3 runs agreed · evidence score 67

How the score was reached

  • Partly verdict base52
  • An open-source build was found+5
  • 4 cited sources+3
  • Price verified on pricing page+3
  • 3/3 assessment runs agreed+4
  • Evidence score67

The base comes from the verdict. Everything under it is a check that either happened or did not, and each one is a fact frozen in this record rather than a judgement made at render time - so the same evidence always produces the same number.

How scoring works →

Cited sources · 4

Every page the run actually retrieved.

Integrity checks

What held up, and what did not.

✓ Price read off the page✓ 3 independent runs, one answer✓ Citations limited to fetched pages! 1 moat recorded