Your Second Brain.
Locally Owned. Blazing Fast. Built for Humans & AI.
A local-first, encrypted knowledge sanctuary designed for deep human reflection and autonomous AI agent memory. Standard plaintext Markdown on your disk, instant sub-millisecond search, zero cloud lock-in, and zero Electron bloat.
One-Line Sovereign Quickstart
Deploy your local second brain and launch your markdown vault in 60 seconds:
curl -fsSL https://sphene.app/install.sh | bash
Built Without the Compromises of Legacy PKMs
Most note-taking apps force you to choose between slow Electron memory bloat or closed proprietary cloud silos. Sphene delivers all three: Light, Fast, and Secure.
LIGHT: Zero Electron Bloat
The Problem: Apps like Obsidian rely on Chromium and Node runtimes, consuming 800MB–2GB of RAM just to edit text notes.
The Sphene Advantage: Sphene is a compiled native engine running quietly in the background consuming <25MB of RAM—whisper-quiet on any laptop, homelab, or workstation.
FAST: Instant Sub-Millisecond Search
The Problem: As vaults exceed thousands of notes, JavaScript event loops and Dataview queries lag and freeze your workspace.
The Sphene Advantage: Sphene embeds an SQLite relational index with FTS5 search. Queries and [[Wikilink]] lookups execute in under 2 milliseconds (<180µs benchmarked).
SECURE: Plaintext Markdown & Encryption
The Problem: Unsandboxed community plugins can read your entire drive, while notes sit in unencrypted plaintext or closed cloud databases.
The Sphene Advantage: Notes live on your physical disk in standard plaintext Markdown with optional AES-256 encryption. Extensions run in cryptographically verified sandboxes.
Designed from the Ground Up for Autonomous AI
Connecting AI agents shouldn't mean letting bots silently corrupt your knowledge. Sphene gives agents instant memory recall while keeping you in total control.
Native Agent Gateway (MCP & REST/SSE)
Connect Claude Desktop, Cursor, or Hermes Agent in seconds via official Model Context Protocol (MCP) over stdio, local sockets, and change streams.
The Differential Timeline ("Human Veto")
Never fear AI hallucinating or overwriting your notes. Agent edits are cleanly staged at the block level for your visual review with 1-click accept or rollback.
Hardware-Grade Vault Partitions
Strict architectural boundaries: Workspace/ (collaborative human & agent read/write), Reference/ (human-curated read-only for agents), and Private/ (sealed with AES-256-GCM, zero agent access).
Zero-Trust Sandboxed Extensions
Lightweight WebAssembly isolates consuming <3MB RAM per worker. Enforces declarative capability manifests (path whitelisting, domain-restricted network, zero shell access).
Sub-ms Relational Index (No Dataview)
Replaces slow client-side parsing with an embedded, low-latency relational engine. Agents execute structured queries via /api/v1/query without wasting LLM context tokens.
Interactive 3D Knowledge Graph
Visual force-directed knowledge graph rendered directly from the engine. Smooth traversal across [[Wikilinks]], tags, and backlinks without dragging down browser performance.
Obsidian vs. Notion vs. Sphene
Why independent thinkers, researchers, and AI builders choose Sphene for their second brain.
| Feature / Dimension | Obsidian (Electron Desktop) | Proprietary Cloud (Notion) | Sphene (v2.0 Sovereign) |
|---|---|---|---|
| Memory Footprint | 800MB–2GB RAM (Chromium / Node) | Cloud Tab (300MB+ RAM) | ✓ <25MB RAM (Compiled Native Engine) |
| Search & Relational Query Speed | 200ms–2,000ms (JS event loop lag) | Server RTT (500ms+) | ✓ <2ms (<180µs SQLite FTS5 Index) |
| Autonomous Agent Protocol | Unofficial Community REST plugins | Closed Cloud Webhooks | ✓ Native Model Context Protocol (MCP) + CLI |
| AI Edit Safety & Governance | ✗ Uncontrolled Overwrites | ✗ None | ✓ Differential Timeline ("Human Veto" Review) |
| Extension Security & Sandboxing | ✗ Unsandboxed Node.js (Full disk/net) | ✗ Closed Store | ✓ Sandboxed WebAssembly (<3MB, Ed25519 Signed) |
| Data Ownership & Encryption | Unencrypted Plaintext on disk | Proprietary Cloud Keys | ✓ Plaintext Markdown on Disk + AES-256 |
| Vault Privacy Partitions | ✗ Flat Folder Hierarchy | Workspace permissions | ✓ Workspace / Reference / Private Boundaries |
Take Full Ownership of Your Second Brain
Deploy locally in 60 seconds. Free and open-format forever. Expand to managed cloud sync when you are ready.