Compare/Letta v2.0 vs Onyx

AI tool comparison

Letta v2.0 vs Onyx

Which one should you ship with? Here is the side-by-side panel verdict, pricing read, reviewer split, and community vote comparison.

L

Developer Tools

Letta v2.0

Persistent agent memory server with MCP interface for any IDE or agent

Ship

75%

Panel ship

Community

Free

Entry

Letta v2.0 is an open-source agent memory server that gives AI agents persistent, queryable memory across sessions. The v2.0 release ships a full MCP server interface, letting any MCP-compatible agent framework or IDE read and write to long-term memory without bespoke integrations. A hosted cloud option is also available for teams who don't want to self-host.

O

Developer Tools

Onyx

Self-hosted AI platform with RAG, agents, and 50+ connectors — MIT licensed

Ship

75%

Panel ship

Community

Paid

Entry

Onyx is a fully open-source, self-hostable AI platform that wraps any LLM with enterprise-grade features: retrieval-augmented generation (RAG), deep research flows, custom agents, code execution, image generation, and voice mode. It connects to 50+ data sources via indexing connectors or MCP, making it a full internal AI stack rather than a chat wrapper. The platform recently shipped version 3.1.1 and has accumulated 24.8k GitHub stars. Unlike managed AI platforms, Onyx is self-deployed — teams can run it on Docker, Kubernetes, or Helm, and the Community Edition is entirely MIT licensed with no feature gating. Enterprise features like SSO, RBAC, and audit logging are available for teams that need them. What sets Onyx apart is the combination of depth and openness. Most open-source chat UIs are thin wrappers. Onyx ships agentic RAG that ranked on deep research leaderboards, plus an admin layer for managing connectors, access control, and usage analytics — all without sending data to a third-party cloud.

Decision
Letta v2.0
Onyx
Panel verdict
Ship · 3 ship / 1 skip
Ship · 6 ship / 2 skip
Community
No community votes yet
No community votes yet
Pricing
Open-source (self-hosted, free) / Cloud hosted tier (pricing not publicly listed)
Open Source (MIT) / Enterprise plans available
Best for
Persistent agent memory server with MCP interface for any IDE or agent
Self-hosted AI platform with RAG, agents, and 50+ connectors — MIT licensed
Category
Developer Tools
Developer Tools

Reviewer scorecard

Builder
82/100 · ship

The primitive here is clean and nameable: a stateful memory store with a standard protocol interface, backed by a REST API and now an MCP layer so any compliant client gets read/write access to agent memory without custom plumbing. The DX bet is correct — MCP as the integration surface means you're not writing a bespoke connector for every agent framework, and the REST API means you're not MCP-locked either. First 10 minutes with the repo lands well: docker-compose up, server running, endpoints documented. The specific decision that earns the ship is exposing MCP as a first-class interface rather than an afterthought plugin — that's the right abstraction at the right level of the stack.

80/100 · ship

If you've been paying for Glean or Guru, Onyx is your escape hatch. Self-hosting is straightforward with Docker, and the 50+ connectors cover virtually every data source your team needs. The hybrid search quality is genuinely competitive.

Skeptic
74/100 · ship

Direct competitors here are Mem0, Zep, and whatever memory layer your agent framework ships by default — and Letta beats most of them on one axis: it's the only open-source option in this category with a proper MCP interface rather than a proprietary SDK you have to adopt wholesale. The tool breaks when you need cross-agent memory federation at scale or when your memory retrieval needs go beyond what a single server instance can handle — there's no clear story on distributed deployments yet. What kills this in 12 months is OpenAI or Anthropic shipping native persistent memory tooling that MCP clients can just call directly, making a standalone memory server redundant. What keeps it alive is the self-host requirement for enterprise compliance use cases — that's the real wedge, and it's real enough to ship on.

45/100 · skip

Self-hosting a full AI platform isn't actually free — you're paying in ops overhead, GPU costs, and the engineer-hours to maintain it. The enterprise features that actually matter (SSO, RBAC) are paywalled behind a license that isn't priced publicly, which is a red flag for budget planning.

Futurist
78/100 · ship

The thesis is specific and falsifiable: within 3 years, AI agents will be persistent processes with stateful identities rather than stateless request-response handlers, and the memory layer will become load-bearing infrastructure rather than an app-level concern. What has to go right is MCP achieving genuine protocol-level ubiquity — if it stagnates as a niche IDE feature, Letta's integration surface shrinks considerably. The second-order effect that matters: if this wins, memory management becomes a separate discipline from agent logic, and the team that owns the memory server owns the agent's identity and context budget — that's a meaningful power shift away from the LLM provider toward the infrastructure layer. Letta is early on this trend, not on-time, which is both the risk and the opportunity.

80/100 · ship

Onyx represents a critical counter-movement to AI centralization. As enterprise AI spending scrutiny intensifies, self-hostable alternatives with full data sovereignty will capture the compliance-sensitive markets that hyperscalers are locked out of.

Founder
52/100 · skip

The buyer for self-hosted Letta is a platform engineering team at a company building agent workflows with compliance constraints — that's a real buyer with real budget, but the sales motion to reach them is expensive and the hosted cloud pricing isn't publicly listed, which is a bad signal for a product that needs bottom-up developer adoption to build pipeline. The moat question is the hard one: the MCP interface is a protocol integration, not proprietary technology, and Mem0 and Zep are iterating fast on the same surface. The specific business problem is that open-source-with-a-cloud-tier requires either strong community gravity pulling users toward the hosted product or a killer enterprise feature set — Letta doesn't yet show evidence of either, and "we have an MCP interface" is a feature any competitor can ship in a sprint.

No panel take
Creator
No panel take
80/100 · ship

For content teams that need AI over their own knowledge base without shipping documents to a third-party cloud, Onyx is a genuine solution. The voice mode and image generation are unexpected bonuses that make it a complete workspace.

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