MCP Memory Servers That Work in Claude Code, Cursor and Codex Simultaneously: A Compatibility Matrix for 2026

The question of whether a single memory server can work with Claude Code, Cursor, and Codex simultaneously revolves around three key points: all three clients connecting to the same server, reading and writing the same records, and ensuring that knowledge gained by one tool is available to the others without manual copying. The answer is yes, as all three AI coding tools support the Model Context Protocol (MCP), allowing any MCP memory server to connect to them.

However, whether the server provides shared memory is a different matter, and many setups fail to achieve this.

Open Agentic Brain & Memory (OpenAB), an open-source self-hosted memory layer, was created to address this gap. Users often had to repeat information between clients, leading to inefficiencies. This guide explains what truly works across all three tools, compares memory server types, and evaluates OpenAB's capabilities.

While MCP support alone isn't enough, it's essential for creating a unified memory system. However, a memory server can still fall short by not saving data, not recalling prior information, or keeping memory isolated on one machine. OpenAB provides Level 3 compatibility, where tools automatically receive relevant context at the start of a session, reducing the need for manual prompting and saving tokens.

OpenAB is designed for Level 3 compatibility, automatically briefs tools with at most 2,000 tokens when a session starts and can recall information from up to 10,000 memories in 28 milliseconds on average. It offers cross-machine support, storing encrypted blobs as GitHub assets, and does not require an account. OpenAB's self-hosted nature also ensures that memory stays under your control and does not rely on third-party infrastructure.