Contextium: Open-Source Persistent Context for Claude Code

Contextium is an open-source persistent context framework built specifically for Claude Code. It solves the problem of having to re-explain context in each new Claude Code session by creating a structured repository system that compounds knowledge over time.

What It Does

Contextium organizes information into markdown files across several categories: apps, integrations, knowledge domains, projects, and journals. The core mechanism is a CLAUDE.md file that acts as a context router, telling Claude which files to load based on the current task. This prevents context window bloat by lazy-loading only relevant content.

Key Features

Context Router Table: The CLAUDE.md file contains a routing table that triggers specific file loads:

| Trigger | Load |
|----------------------|-----------------------------------|
| Project work | projects/README.md |
| Person mentioned | knowledge/people/{name}/ |
| Integration/API call | integrations/{name}/README.md |
| Prior work | journal/ (latest) |

Multi-Agent Support: Routes research to Gemini (for cost efficiency) and bulk edits to Codex (for speed) while keeping Claude focused on strategy and decisions
Template Structure: The open-source version ships with 6 sample apps and documentation for 27 integrations
Real-World Scale: The creator's personal instance contains 35 app protocols, 27 integration connectors, 100+ completed projects with decision logs, and 600+ journal entries

Installation and Setup

Install with a single command:

bash curl -sSL contextium.ai/install | bash

The installer uses bash and gum for the terminal UI, asks for your name, selects your AI agent (supports Claude Code plus 8 others), chooses integrations, and sets up your repository. The process takes about 5 minutes and works on macOS and Linux.