Mem0 vs Zep (2026): Architecture, Time-Awareness, Scope, and When to Choose Neither
Comparison · September 2026 · 4 min read
TL;DR
Mem0 and Zep are the two most widely used memory layers for AI agents, and they solve the same problem in different ways. Mem0 extracts facts from each conversation and keeps a compact current memory per user, agent or session, which makes it light and cheap for personalized assistants. Zep builds a temporal knowledge graph on its open-source Graphiti engine, so it records how facts change over time and keeps the old versions as history, which suits agents that need to reason about what was true when. Both are scoped to users, agents or groups and both learn mainly from what their agents see. When several agents and teams need the same company knowledge, built from Slack, email, meetings and tickets rather than chat, the better answer is organization-wide memory: Sentra keeps one shared, time-stamped, permissioned memory from more than 200 tools that every agent reads over REST and MCP. The side-by-side and a decision rule are below.
Mem0 vs Zep at a glance
| Mem0 | Zep | Sentra, for comparison | |
|---|---|---|---|
| Core approach | LLM fact extraction with add, update and delete decisions | Temporal knowledge graph (Graphiti) | Organization-wide fact graph resolved at write time |
| Memory scope | Per user, agent or session | Per user, agent or group graph | Shared across every agent and person in the company |
| History of changes | Updates replace prior values | Keeps invalidated facts as history | Bi-temporal: when a fact became true and when it stopped |
| Learns from | Conversations | Conversations and business data you ingest | 200+ tools: Slack, email, meetings, tickets, docs, CRM |
| Permissions on memory | Per scope you define | Per graph | Inherited from each source system |
| Open source | Yes, core library | Graphiti engine | No, managed with VPC and on-prem options |
| Best for | Personalized assistants and copilots | Conversational agents tracking changing state | Several agents and teams on one current view of the company |
Where Mem0 wins
Mem0 is the simpler system to adopt. A single call adds memory, the write path keeps memory compact by deduplicating and resolving conflicts as facts arrive, and retrieval sends the agent only a small working set. For a customer-facing assistant that should remember each user's preferences, plan and history across chats, that is exactly the right trade: low latency, low token cost, and little to operate.
Where Zep wins
Zep is built for time. Its graph records entities and relationships and marks a fact as invalid when newer information contradicts it, instead of overwriting it. An agent can ask what is true now and what was true on a past date, and every fact traces back to the episode that produced it. For agents in regulated or long-running settings, where why something changed matters as much as what it is now, that history is worth the extra structure.
When to choose neither
Both tools answer "what does this agent know about this user?" Many teams are actually asking "what does the company know?" A support agent, a sales agent and a coding agent that all touch the same customer need the same facts, including decisions made in a Slack thread or a meeting that none of them attended. Keeping that in per-agent memory means five partial copies that drift apart.
That is the case Sentra is built for. It reads the company's tools directly, resolves each message, meeting, ticket and document into facts with a validity window and permissions, and serves one memory to every agent and person. On Terminal-Bench 2.1 the Sentra-enabled agent scored 88.31% mean reward against an 83.37% baseline at 72.6% lower model cost, because the agent read resolved facts instead of raw context. Teams sometimes run both layers: Mem0 or Zep for per-user conversational memory, Sentra for company knowledge.
How to choose
- One assistant needs cheap, compact memory of each user: Mem0.
- An agent needs to know how a user's situation changed over time, with history: Zep.
- Several agents and teams need the same current company knowledge from Slack, email, meetings and tickets: Sentra.
Frequently Asked Questions
Is Zep better than Mem0?
Neither is better in general. Zep keeps a temporal graph with history; Mem0 keeps a lighter current memory. Choose Zep when change over time matters and Mem0 when simplicity and cost matter.
Which is cheaper, Mem0 or Zep?
Both offer open-source components and managed plans. Mem0's compact memory usually means fewer tokens per call; Zep's graph adds structure and storage. Model cost is dominated by how much context each call sends.
Can Mem0 or Zep share memory across multiple agents?
Both let you define scopes such as users or groups, so sharing is a design choice within those scopes. Sentra shares one organization-wide memory across all agents by default.
Do Mem0 and Zep ingest Slack or email?
They learn mainly from the conversations and data you send them. Sentra connects to Slack, email, calendars, meetings, tickets and CRM directly.
What are the best alternatives to Mem0 and Zep?
Sentra for organization-wide memory, Letta for stateful autonomous agents, and Cognee or Graphiti for open-source graph memory.
Which Sentra is this?
Sentra at sentra.app is an organizational memory layer for teams and AI agents. It is unrelated to Sentra.io, the data security company.