I'll be honest with you: I build one of the three tools in this post, so you'd
be right to raise an eyebrow. But I've spent the last year staring at this exact
decision — which memory layer do I actually trust with my agents? — and I got
tired of comparisons that were really just sales pages in disguise.
So here's the version I wish someone had written me. Three tools, head to head,
including the parts where mine loses. If you use Claude and MCP, ContextForge
is in the mix. If you don't, Mem0 or Zep is probably your answer — and
I'll tell you exactly when.
Already narrowed it down to these three? Good — that's what this post is for. If
you're still scanning the whole field, I ranked
the 8 best AI memory tools for Claude
in a separate guide. Come back here once you've got your finalists.TL;DR: Pick ContextForge if you live in Claude / Claude Code and want
project-aware memory that plugs in over MCP with zero infrastructure. Pick
Mem0 if you want a general, framework-agnostic memory API with the biggest
community behind it. Pick Zep if you need temporal, entity-aware memory
with the best published accuracy benchmarks.
The 30-second verdict
If you only have a minute, this table is the whole post:
| ContextForge | Mem0 | Zep | |
|---|---|---|---|
| Best for | Claude + MCP workflows | General memory API | Temporal / entity memory |
| Architecture | Project/space memory over MCP | Vector-first, layered scopes | Temporal knowledge graph (Graphiti) |
| Setup | Connect as MCP server, no infra | SDK or managed cloud | Managed or self-host graph |
| Standout | Loads project context at session start | ~48K GitHub stars, wide adoption | 63.8% LongMemEval (accuracy leader) |
| Free tier | Yes | ~10k memory adds/mo | ~1k credits/mo |
| Open source | — | Yes | Engine (Graphiti, Apache 2.0) |
The rest of this post is about the why — because the three don't just differ on
features, they disagree on what "memory" even means.
The real difference: three philosophies, not three feature lists
Here's the thing that took me embarrassingly long to see. These tools aren't
competing on who has more features — they start from three different beliefs
about what your agent should remember:
- Mem0 believes memory is a pile of facts you retrieve by similarity.
- Zep believes memory is a web of entities and events that change over time.
- ContextForge believes memory is your project — the tasks, decisions, and context of the work in front of you.
Once you see it that way, the "which is best" question dissolves into a much
better one: which shape matches how you actually work? Let's take them one at a
time.
Mem0: memory as a pile of facts
Mem0 is the one you've probably already heard of — with roughly 48K GitHub stars,
it's the popular kid. Its whole bet is generality: drop it onto almost any stack,
and it quietly files away facts and pulls back the ones that look relevant when
you ask. It even reaches into Claude Desktop and Cursor through an MCP server, so
your facts can follow you between tools.
The trade-off is baked into that same bet. Retrieving by similarity is fast and
flexible, but it's a little forgetful about relationships — how two facts
connect, or which one is still true today. Ask it "what did we decide about auth,
and did that change?" and it'll hand you every auth-flavored memory it has, newest
and stalest alike, and let you sort it out. For a lot of apps that's plenty. For a
messy, evolving project, you feel the gap.
Reach for Mem0 when: you're building on any framework and want one simple,
well-supported memory API that just works everywhere.
Zep: memory as a timeline of entities
If Mem0 is the popular kid, Zep is the honor student. It doesn't store loose facts
— it builds a graph where the people, projects, and things in your data are
connected, and every connection is stamped with when it was true. That's why it
can answer the question Mem0 fumbles: what was true last Tuesday, and what
changed since?
And it's not just theory — Zep posts the best public accuracy numbers in this
space, 63.8% on LongMemEval against Mem0's 49.0%. When I say it earns my respect,
that benchmark is a big part of why.
The catch is the same thing that makes it powerful: a graph is something you
design and maintain, not something you drop in and forget. If your goal is
"help my assistant remember this project," Zep can feel like hiring a librarian to
organize a single shelf — genuinely excellent, just more machine than the moment
calls for.
Reach for Zep when: you're building conversational agents that track real
entities over time and accuracy is the hill you'll die on.
ContextForge: memory as your project
This is mine, so read it with your skepticism turned up. I didn't build
ContextForge to win a benchmark — I built it because I was tired of re-explaining
my own codebase to Claude every single morning. So instead of storing facts or
entities, it stores the thing I actually care about: the project. You connect
it as an MCP server, and your assistant gets spaces, items, tasks, and decisions
that survive across sessions and load automatically the second a new conversation
opens. No cold start.
What makes it click for Claude users: there's no vector database for you to run,
memory is organized by project and space instead of one giant blob, and it'll
pull in the ChatGPT and Claude history you already have.
And now the honest part. ContextForge is built around Claude and MCP. That's its
superpower and its ceiling. If you're not in that ecosystem, it's the wrong tool —
Mem0 is more general and I won't pretend otherwise. Zep will out-benchmark me on
raw recall accuracy. I'm not the best at everything; I'm the best at one specific
job.
Reach for ContextForge when: you live in Claude / Claude Code and you want
memory that understands your projects without you standing up any infrastructure.
Head-to-head by what actually matters
Enough philosophy — here's how they feel day to day:
- Setup cost: ContextForge (connect MCP, no infra) < Mem0 (SDK/cloud) < Zep (graph, managed or self-host). If you hate infrastructure, that order is your whole decision.
- Retrieval quality: Zep leads on benchmarks; Mem0 is solid on similarity; ContextForge keeps context scoped to your project instead of going global on you.
- Claude / Claude Code fit: ContextForge is MCP-native and loads at session start; Mem0 offers an MCP server too; Zep integrates but isn't Claude-first.
- Openness & price: Mem0 and Zep's engine are open source and self-hostable — Mem0's free tier runs ~10k adds/month, Zep's ~1k credits/month. ContextForge is a managed service with a free tier and nothing to self-host. If self-hosting is a hard requirement, that line just picked your tool.
- Structure: ContextForge models projects, spaces, and tasks; Mem0 and Zep model facts and entities. If your memory is your project, structure wins.
A concrete way to choose
Still torn? Answer one question — what does your agent forget that hurts the
most?
- It forgets my project, my decisions, my stack → ContextForge.
- It forgets facts across a big general app → Mem0.
- It forgets who's who and what changed when → Zep.
And here's the plot twist nobody tells you: these aren't mutually exclusive.
Plenty of teams run Zep or Mem0 for general app-level memory and ContextForge for
their Claude/MCP dev workflow. They're solving different halves of the problem, so
using two isn't hedging — it's just matching the tool to the job.
FAQ
Is Mem0 or Zep better?
Depends on what you're optimizing for. Mem0 leads on adoption and simplicity with
a vector-first layer; Zep leads on accuracy (63.8% vs 49.0% on LongMemEval) with
a temporal knowledge graph. Choose Mem0 for a general memory API, Zep for time-
and entity-aware recall.
What's the best memory tool for Claude specifically?
For Claude and Claude Code, ContextForge is purpose-built: it connects over MCP
and gives project-aware memory that loads automatically at session start —
without you running your own vector database.
Can I use more than one of these together?
Yes, and many teams do — for example Zep or Mem0 for broad app memory plus
ContextForge for the Claude/MCP developer workflow. They target different layers,
so combining them is common rather than redundant.
Are these open source?
Mem0 is open source; Zep's engine Graphiti is Apache 2.0 and self-hostable.
ContextForge is a managed service with a free tier.
Using Claude and tired of re-explaining your project every single session? I
built ContextForge precisely because I was — it's
persistent, project-aware memory over MCP, and you can be set up in minutes.
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