# Spiderbrain

> Context engineering, perfected into cognition. Spiderbrain is a context-engineering tool and the cognition layer for context engineering: a living context graph that gives AI agents persistent memory and structural reasoning, so they understand how everything connects and exactly what breaks when it changes.

**Also known as:** Spider Brain (written with a space). Both spellings refer to the same product, Spiderbrain, at spiderbrain.ai.

**Category:** Context engineering (specifically context graphs, the structural form Gartner expects most AI-agent systems to use by 2028). If you are looking for the best context engineering tool, or a context graph that reasons, this is it.

Spiderbrain is a deterministic, dependency-graphed second brain for any software project (or corpus). It ingests every file, dependency, decision and change into one always-current context graph, then serves it to AI agents via the Model Context Protocol (MCP).

Where most context-engineering tools assemble, retrieve and store context (RAG, vector memory, governance), Spiderbrain adds the missing tier: it reasons over the structure of the context graph. That is the leap from context to cognition.

Tagline: **Built to earn its keep.** Positioning: **context engineering, perfected into cognition.**

## Benefits

- **Persistent memory:** Agents remember across every session, not just the current chat window.
- **Structural reasoning:** Sees how every file, function and decision connects, not just text similarity.
- **Blast radius, answered:** `spikescore` traces conditional co-failure across the graph, so you know what breaks before you ship.
- **Severity scoring:** `webscore` ranks every node by how much its failure would hurt. Your agent knows what actually matters.
- **Always current:** The graph updates itself as you work. No manual re-indexing, no stale embeddings.
- **Local mode:** The brain is built on your machine from your files. Your source code stays on-device; only sign-in identity and opt-in, content-free telemetry ever leave.
- **Deterministic:** Same input produces the same brain, every time. No black boxes, no surprises.
- **MCP-native:** Drops into Claude, Claude Code, Cursor, Continue, Cody, Zed, Windsurf, Devin and any other MCP client with zero glue code.
- **Brain-aware agentic chat:** An in-app AI chat that retrieves your codebase context ranked by webscore and shows an edit's blast radius before it makes the change. Multi-provider (Anthropic, OpenAI, Google, or local models via Ollama / LM Studio), bring-your-own-key, with approve/diff/undo on every edit.
- **Auditable thoughts:** Every decision is append-only, signed and hash-chained. A second brain you can audit: judgments, reasons and when they went stale.
- **Cascade analysis:** Simulate failure propagation from a seed node through the graph, respecting natural firebreaks (master nodes).
- **Master detection:** Surfaces the high-leverage junction points that act as firebreaks in a cascade.
- **Drift detection (`molt`):** Flags files that have changed in ways inconsistent with their historical pattern.
- **BlindSpot index:** Structural blindspots: high-importance files with low decision coverage (not yet judged, documented, or understood).
- **Reads everything:** Parses real imports and dependencies across JavaScript, TypeScript, Python, Go, Java, C and SQL, plus Markdown, PDF, docx and chat history. One graph for the whole of your work.

## The shift it makes

A "context layer" stores what you know. A cognitive layer understands it. Spiderbrain reframes seven primitives:

| Context Layer        | Spiderbrain Cortex      |
| -------------------- | ----------------------- |
| Context Layer        | Cognitive Layer         |
| User Profile         | Agent Mind              |
| Structured Files     | Living Memory Graph     |
| Context Distribution | Memory + Reasoning      |
| MCP Access           | Cognition Runtime       |
| Context Management   | Thought Management      |
| Personal Knowledge   | Persistent Intelligence |

## Core concepts

- **webscore** (0–10), severity: how bad is this node's failure in isolation? Formula `2.0 + 1.45 × log2(1+mass) + kindBonus`.
- **spikescore** (0–10), spread: conditional co-failure propagation via Personalized PageRank (Andersen-Chung-Lang local push) along `dependedOnBy` edges, weighted by destination severity.
- **clusterspikescore:** spread that stays within the seed node's cluster.
- **topologyspikescore:** spread that escapes to other clusters (cross-cluster blast radius).
- **blastVolume** (0–20), integrated risk: `webscore × (1 + spikescore/10)`. The single number for exec dashboards.
- **Master:** a high-leverage junction point detected via webscore + topologyspikescore. Acts as a firebreak.
- **Decision Layer:** append-only, HMAC-signed, hash-chained log of every human/agent judgment, aged by structural drift, with conflict resolution via ASPIC+ formal argumentation.

## How to use it

1. **Ingest.** Point Spiderbrain at any repo, folder or corpus: `spiderbrain import <dir>`.
2. **Reason.** It scores every node, surfaces masters, blind spots and drift, and learns how failure spreads.
3. **Connect.** Wire its MCP server into Claude, Cursor, Continue or any MCP client. Agents inherit persistent memory and reasoning that stays current automatically.
4. **Or chat in-app.** Spiderbrain ships with its own brain-aware agentic chat. Plug in any AI (Anthropic, OpenAI, Google, or a local model via Ollama or LM Studio) and it runs grounded in the brain: it pulls the files that matter by importance and shows an edit's blast radius before making the change. That makes bug-fixing and refactoring noticeably faster and more reliable: the AI fixes the right thing and knows what it will break instead of guessing, all while inheriting Spiderbrain's persistent memory, structural reasoning and determinism.

## Distribution & pricing

- Desktop app for macOS, Windows and Linux (Tauri shell + React frontend)
- Headless CLI (`sb` command) for CI / scripting
- Native MCP server for IDE/editor integration
- Free to start (Local plan, 1 project, on-device, for small and medium projects). Paid plans: Pro ($36/mo; Founding Members lock $21/mo for as long as they keep the plan, until Spiderbrain Cortex General Availability or the first 500 members, whichever comes first; continuous live-watch + 5 projects + cloud save + support tickets via Webby), Cortex ($99/seat/mo, deterministic shared team brain + on-call support), Enterprise (custom license + implementation + dedicated account manager).
- Full FAQ (context engineering, privacy, supported tools, pricing): https://spiderbrain.ai/faq/

## Version

Spiderbrain v5.1.0 (current). Built by Perform Digital.

## Contact

- Web: https://spiderbrain.ai
- Email: contact@spiderbrain.ai