Agentic Index
Letta vs Zep (2026)
Choose Zep for a temporal knowledge graph memory service behind your existing agents, and choose Letta for a stateful agent platform where memory persistence is built into the runtime. That verdict is the Agentic Index coverage score, graded from each vendor's own published materials.
Zep offers a free tier with 1,000 credits a month and Flex from 125 dollars a month, while Letta offers a free tier, Pro at 20 dollars a month, a usage based API, and open source self hosting. Zep's graph tracks how facts change over time, which suits assistants grounded in evolving user data; Letta suits teams betting on stateful agents as the architecture, with the caveat that its recent momentum concentrates in Letta Code.
On the Agentic Index agent infrastructure ranking, neither Letta nor Zep clears the bar, which asks for all five production contract capabilities documented in full. Letta documents two of the five in full; Zep does not document testing, debugging and optimization in full, nor observability and auditability. 34 of the 186 vendors in the lane clear it. See the agent infrastructure ranking
This comparison is published by Agentic Index, an independent agentic AI vendor research platform. Letta and Zep are each graded against the same 14 capability Agentic Index taxonomy, from the vendor's own public materials under the Agentic Index verification standard, alongside 956 researched vendors. No vendor pays for placement and no vendor has reviewed this page. How this evidence is graded
Choose Letta if
- You want the whole agent lifecycle, including memory, in one open source runtime
- Editing and inspecting agent memory directly is part of your workflow
- A 20 dollars a month entry point for hands on use fits early experimentation
Choose Zep if
- Facts about your users change over time and your memory layer must model that
- You want a managed memory service with a knowledge graph, not a new runtime
- Keeping your current framework while upgrading recall is the goal
| At a glance | Letta | Zep |
|---|---|---|
| Category | Agent infrastructure | Agent infrastructure |
| Entry price | Free tier · Pro $20/mo · API plan $20/mo plus usage · self-host free | Free (10,000 credits/mo) · Flex $125/mo · Flex Plus $375/mo · Enterprise custom |
| Free / trial | Free account, no card (up to 3 agents with managed state; BYOK unlimited locally) | Free plan: 10,000 credits a month (1 credit per Episode up to 350 bytes), no rollover. Open source Graphiti engine is free to self host. |
| Pricing confidence | public exact | public exact |
| Feature | L Letta |
Z Zep |
|---|---|---|
| Action & orchestration | ||
|
Integrations & Tool Calling Ability to connect agents to real systems through native integrations, OAuth-authenticated actions, custom tools, APIs, webhooks, or MCP-compatible tools. |
Full / Explicit | Partial |
|
Workflow Orchestration Ability to sequence, branch, retry, route, and combine deterministic workflow nodes with autonomous agent steps. |
Full / Explicit | No / Not documented |
|
Triggers & Channel Coverage How agents wake up and where they work: schedules, webhooks, message events, CRM events, inbox events, chat, email, voice, and collaboration tools. |
Full / Explicit | No / Not documented |
| Knowledge & context | ||
|
Knowledge Grounding & RAG Ability to ground agent behavior in company data through document ingestion, retrieval, external knowledge APIs, semantic search, or RAG layers. |
Partial | Full / Explicit |
|
Memory & State Persistence Ability to persist context across a run, conversation, workflow, user, team, or longer-term memory layer. |
Full / Explicit | Full / Explicit |
| Control & trust | ||
|
Human Oversight & Guardrails Approval steps, consent checkpoints, escalation rules, structured guardrails, policy constraints, and pause/resume controls. |
Full / Explicit | No / Not documented |
|
Security, Identity & Governance RBAC, SSO, auditability, encryption, least-privilege tool access, compliance posture, and data handling policy. |
Partial | Full / Explicit |
|
Observability & Auditability Traces, logs, execution histories, metrics, audit events, and debugging detail for production agent behavior. |
Partial | Partial |
|
Deployment & Data Residency Deployment modes and options, including SaaS, dedicated cloud, VPC, on-prem, hybrid, local runtime, and self-hosting. |
Full / Explicit | Full / Explicit |
| Solution readiness | ||
|
Prebuilt Agents, Templates & Packs Ready-made workflows, packaged employees, templates, blueprints, industry solutions, and role-specific agents that reduce time-to-value. |
Partial | No / Not documented |
| Platform extensibility | ||
|
Model Flexibility & Routing Ability to work across multiple foundation models, route tasks to different models, or let buyers bring their own providers and keys. |
Full / Explicit | Full / Explicit |
|
APIs, SDKs & MCP Extensibility Composability layer: stable APIs, SDKs, MCP tool consumption/serving, custom tools, and integration into internal systems. |
Full / Explicit | Full / Explicit |
|
Testing, Debugging & Optimization Testing, debugging, scoring, retries, fallbacks, quality gates, and optimization loops for improving agent workflows before and after deployment. |
No / Not documented | No / Not documented |
| Specialist automation | ||
|
Browser & Computer Use Browser, desktop, or remote/local computer control for workflows that cannot be handled through stable APIs alone. |
No / Not documented | No / Not documented |
Pricing snapshot
Sourced from the Index pricing dataset · open each vendor's profile for full detail.
| Pricing | L Letta |
Z Zep |
|---|---|---|
|
Entry price Lowest public entry point |
Free tier · Pro $20/mo · API plan $20/mo plus usage · self-host free | Free (10,000 credits/mo) · Flex $125/mo · Flex Plus $375/mo · Enterprise custom |
|
Pricing confidence How public the numbers are |
Public, exact | Public, exact |
|
Billing Primary billing axis |
usage | Subscription tiers plus credits consumed by data ingestion (1 credit per Episode up to 350 bytes, +1 per additional 350 bytes); retrieval, storage, threads, users, and graph storage consume zero credits |
|
Variable cost Workload / overage exposure |
High variable cost | Low variable cost |
|
Free tier / trial Try before you buy |
Free tier
|
Free tier
|
|
Buying motion Self-serve vs sales call |
Mixed | Self-serve |
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