Where Your Memo Travels,
and Where It Never Stays
"It writes to my local vault — so why does a server appear at all?" This is the question we hear most from Obsidian users, and this page answers it as a route map. What we do well (local-only vault appends, on-device AI, no server retention) and what we deliberately don't do (end-to-end encryption) are written at the same resolution.
The data path of a single memo
- Created on your device — protected with AES-GCM-256A memo first enters the on-device Outbox (the unsent queue). Simple Memo - for Obsidian encrypts the on-device Outbox queue and send history with AES-GCM-256 via Apple's CryptoKit. The 256-bit symmetric key is stored in Apple Keychain with protection against migration to another device; the app reads it for encryption and decryption. Backup copies of the key also cannot be used on another device. Before changing devices, confirm that important memos have reached their destination. Key management details and Apple's explanation. Offline, the memo waits here and auto-resends when the connection returns.
- Append to your Obsidian vault — entirely localWith the Obsidian integration enabled, the append is a direct file write into the vault folder on your device (with a URI fallback when direct access isn't possible). No plugin, no external server — the network never appears in this path.
- AI tagging — completed on-deviceThe automatic title (up to 20 characters), 1–3 tags, and type (todo / idea / log) are generated by on-device AI via Apple Foundation Models, entirely on your iPhone. Memos are not sent to an external server for tagging. Devices without Apple Intelligence fall back automatically to on-device lightweight formatting.
- Email send — passes through over TLS, never storedOnly at send time does the body pass through our relay API (Cloudflare Workers) and the delivery provider (Resend), over TLS. Memo bodies are not persistently stored on our servers, and they are not written to logs. The client uses
URLSessionConfiguration.ephemeral— no cookies, no caches. - Into your own inbox — delivered over standard SMTP (= not E2EE)Final delivery is standard SMTP. That is exactly why you can read your memos in your regular mail client — and also why Simple Memo - for Obsidian is not end-to-end encrypted. See "Stated plainly" below for the reasoning behind this trade-off.
What stays on a server — and what never does
| Data | Where | Retained? |
|---|---|---|
| Memo body | Our servers (relay / delivery) | No — transit only during send, not logged |
| Memo body | Your email inbox | Yes (that is the point) |
| Memo body | Your Obsidian vault (if enabled) | Yes — local, on your device |
| Outbox & send history | On-device only | Encrypted with AES-GCM-256 |
| Email address | Cloudflare D1 | Send IDs mapped to recipient email hashes, independently of reminder opt-in. Records older than 35 days are removed by scheduled cleanup |
| Usage events, device identifiers, and diagnostics | Cloudflare D1 | Events older than 90 days are removed by scheduled cleanup. Send IDs can link events to recipient email hashes |
| Tagging input (memo body) | External servers | Never sent — processing is on-device |
Memo protection and usage analytics
Within the iOS app, CryptoKit encrypts memo bodies, Keychain stores the key, and URLSession transmits memos. GoogleSignIn and Firebase Authentication support optional email auto-fill; Firebase App Check protects backend access. The app also uses first-party usage analytics and the AppsFlyer SDK.
First-party analytics records installation and session identifiers, usage events, and send outcomes. The app sends AppsFlyer events for first successful memo send, successful verification, paywall views, plan selection, and successful purchases. The same installation identifier is set as its Customer User ID. Event fields set by the app exclude raw email addresses, memo text, and verification codes, but first-party send IDs can link to recipient hashes, and acquisition and usage records can be connected. This analytics is not fully anonymous. See our Privacy Policy for details.
Stated plainly — this is not E2EE
Simple Memo - for Obsidian is not end-to-end encrypted — emails are delivered over standard SMTP. "Readable in your regular mail client" and "only you hold the decryption key at every hop" cannot both be true; we chose the former, by design.
The on-device Outbox queue and send history are encrypted with AES-GCM-256, but that is on-device protection, not a substitute for E2EE (what E2EE is, and why this app doesn't qualify).
If E2EE is a hard requirement for you, an E2EE-designed notes app such as Standard Notes is the better fit. With that stated, our commitments are: memo bodies never stored on our servers, tagging completed on-device, and vault appends performed locally.
Frequently asked questions
Is any external server involved in the Obsidian vault append?
No. The append is a direct file write into the vault folder on your device (URI fallback when direct access isn't available), with no plugin and no network involved. Local draft saves that don't involve sending an email also stay entirely on-device.
Does AI tagging send my memo to Apple or anyone else's servers?
No. Tagging runs on-device via Apple Foundation Models with no network calls, and memos are not sent to an external server for tagging. On devices without Apple Intelligence, it falls back to on-device lightweight formatting — still with nothing sent externally. Details on the AI auto-tagging page.
Why not make it E2EE?
Because the destination is your everyday email inbox. If your mail server can show you the memo, it can decrypt it — so E2EE is structurally impossible here. Choosing E2EE would require a dedicated client and give up the "readable on any device, in any mail app" property this app exists for. For E2EE-first needs we genuinely recommend Standard Notes and similar apps.
How does this page relate to the Privacy Policy?
The legally binding text is the Privacy Policy (especially §12, "Technical notes on encryption"). This page rearranges the same facts as a route map, organized around what Obsidian users ask most — whether things stay local. If they ever disagree, the Privacy Policy wins.
