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They give you memory.
We give you an entire toolkit.

SynaBun is an open-source, self-hosted AI workspace and persistent memory MCP server; Mem0, Letta, Memory Keeper and ContextStream focus on memory or on agents. Here is how they compare on MCP tools, storage, license and hosting, as of October 21, 2026.

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FeatureSynaBunMem0LettaMemory KeeperContextStream
What it isAI workspace and memory MCP serverMemory layer: library and hosted platformAgent platform (formerly MemGPT)Context MCP server for coding assistantsHosted context service with an MCP client
MCP tools158 (141 on by default)11 (hosted MCP server)6 (hosted MCP server)38 (full profile)20 tool domains
Where memory livesSQLite on your machineLocal Qdrant, Postgres with pgvector, or Mem0 PlatformMarkdown files in git, locally or in Letta CloudSQLite on your machineContextStream's servers
Managed cloudNoYes, free and paid plansYes, free and paid plansNoYes
Open sourceApache 2.0Apache 2.0 (library)Apache 2.0MITMIT (client only)
Beyond memoryAssistant with worker agents, browser automation, social media tools, whiteboard, loopsMemory onlyAgent runtime and SDKContext, session and checkpoint toolsCode search, sessions, project context

Competitor facts checked on October 21, 2026 against each project's repository, documentation and pricing (sources below). SynaBun facts are from its source code. Products change: check the sources for the latest.

SynaBun vs Mem0

Mem0 is a memory layer for AI applications: an Apache 2.0 open-source library and the hosted Mem0 Platform, whose MCP server has 11 memory tools. Out of the box the library uses OpenAI for its embeddings (text-embedding-3-small) and its LLM, so it needs an OpenAI API key, though it can run on local models such as Ollama. SynaBun computes embeddings on your machine with all-MiniLM-L6-v2 and stores memory in SQLite, with no API key, and the same install adds the Assistant, browser automation, social media tools, a whiteboard and autonomous loops. If memory is a feature of a product you are building, Mem0 is the focused choice; if you want your own coding agents to remember, SynaBun covers more in one install. Read the full SynaBun vs Mem0 comparison.

What happened to OpenMemory?

OpenMemory, Mem0's local MCP memory server with 5 tools, has been discontinued: Mem0 announced its end in April 2026 and removed it from its repository in July 2026. If you used it, SynaBun is a local MCP memory server that keeps its data in SQLite on your machine.

Why Tool Count Matters

Memory servers differ in scope. Mem0's MCP server has 11 tools, all about memory; Memory Keeper has 38 for context, sessions and checkpoints. SynaBun's 158 tools go further: your agent can remember context, open a browser to test your UI, read social media, generate images with Leonardo.ai, manage a Discord community and run autonomous loops, all from one MCP connection. The Universal MCP Management screen also installs and syncs third-party MCP servers across Claude Code, Codex, Gemini CLI and OpenCode. Fewer separate installs means fewer things to configure and fewer things to break.

For a deeper look at how SynaBun's architecture works: External Models as Agents explains the memory bus architecture, and Claude Code Skins Research shows how SynaBun extends AI coding environments.

SynaBun vs Letta (formerly MemGPT)

Letta grew out of MemGPT, a 2023 UC Berkeley research paper, and is now an agent platform built around Letta Code. Its current memory system, MemFS, keeps an agent's memory as Markdown files in git, with memory blocks always in the prompt and no vector index by default; the older core, archival and recall memory belongs to its legacy V1 SDK. Letta is Apache 2.0, runs locally or in Letta Cloud (free and paid plans), and offers a hosted MCP server with 6 agent-management tools. SynaBun takes the other side: it does not build agents, it gives the coding agents you already use a shared local memory and tools. Pick Letta to build a product with agents of its own; pick SynaBun to make Claude Code, Codex or OpenCode remember. Read the full SynaBun vs Letta comparison.

SynaBun vs Zep

Zep is a hosted context platform built on Graphiti, its open-source (Apache 2.0) framework for temporal knowledge graphs. Zep Cloud has a free tier and paid plans; the self-hosted Zep Community Edition was discontinued in April 2025. If you build a customer-facing application that needs a knowledge graph of its users, Zep is purpose-built for that. SynaBun is fully open source and keeps memory in a local SQLite file you own, for the coding agents on your own machine.

Memory Keeper and ContextStream

Memory Keeper is an MIT-licensed MCP server for persistent context in AI coding assistants: it stores context in SQLite on your machine and has 38 tools in its full profile (smaller profiles have 8 and 22), for sessions, checkpoints and search. ContextStream is a hosted service: its MCP client is open source (MIT), and the indexed context lives on ContextStream's servers, so it does not work offline.

Which One Should You Pick?

If you want one MCP server that gives Claude Code, Codex, Gemini CLI, OpenCode, Cursor or Windsurf persistent local memory plus the Assistant, a browser and automation, pick SynaBun. If memory is part of an application you are building, look at Mem0, or at Zep for a knowledge graph. If you are building a product with its own agents, Letta is the framework. The long version of this comparison, with the architecture of each server, is MCP Memory Servers: SynaBun vs mem0 vs Letta vs Zep. SynaBun is for agentic work on your own machine: agentic coding covers autonomous workflows, vibe coding covers conversational ones, and social media automation covers the browser tools.

For deeper architectural reasoning, read External Models as Agents on multi-agent memory bus design, Cross-Compatible Sessions on portable AI sessions, and OpenCode + Ollama for fully local agentic coding setups.

Sources

Checked on October 21, 2026.