Context Mode started as an open-source MCP server and plugin for AI coding agents, now branded the Context Mode Engine. It attacks context-window bloat from tool output. Instead of letting raw Playwright snapshots, logs, API responses or file dumps flow into the conversation, its sandbox tools (ctx_execute, ctx_execute_file, ctx_batch_execute) run code in an isolated subprocess, and only stdout reaches the model. Larger outputs can be indexed into a local SQLite FTS5 knowledge base and retrieved with BM25 search (ctx_index, ctx_search, ctx_fetch_and_index).
The Engine also tracks session events such as file edits, git operations, tasks, errors and decisions in SQLite. After the agent compacts its conversation, it retrieves only the relevant events instead of re-injecting everything. Hooks (PreToolUse, PostToolUse, SessionStart, PreCompact and others, depending on the host) route the agent toward the sandbox tools. The sandbox supports 12 language runtimes.
The project's README reports large savings from its own benchmarks, for example a 56.2 KB Playwright snapshot reduced to 299 B. It also says 315 KB of raw output in a full session becomes 5.4 KB, which is the source of the widely quoted "98% reduction" figure. These numbers are vendor-measured on selected scenarios and have not been independently verified, so real savings depend on your workload.
Platform support is broad. The README compatibility table lists 18 hosts, including Claude Code, Codex CLI, Gemini CLI, Cursor, VS Code Copilot, GitHub Copilot CLI, OpenCode, Kiro and Antigravity. Hook coverage differs per host, and Claude Code has the most complete integration via its plugin marketplace.
The Engine is licensed under the Elastic License 2.0 (source-available, not OSI open source). You can use, fork, modify and redistribute it, but you may not offer it as a hosted or managed service or remove licensing notices. The README states that the Engine sends no telemetry and needs no account, with data kept in local SQLite databases.
In 2026 the company added a separate hosted product, positioned as a control plane for coding agents. It is installed with npx @context-mode/cli (MIT-licensed npm package) and sits between Claude Code or Codex and the model provider, adding context saving, session recall, memory and Protect policy rules. That hosted gateway runs in Context Mode's cloud, a dedicated instance, or the customer's Cloudflare account on Enterprise, so its data path differs from the local-only Engine. Pricing for the hosted product is request-based, and the Engine plugin remains free.
