# Letta vs SOAT: Feature Comparison

> Letta and SOAT compared on 15 agent capabilities, 7 vs 12 native, each rating linked to its source.

# SOAT vs Letta

Letta is agent infrastructure (Apache-2.0, self-hosted or managed). SOAT is agent infrastructure (Apache-2.0, self-hosted). Of the 15 capabilities the [benchmark](/benchmark) tracks, Letta covers 7 natively and SOAT 12.

## At a glance

| | Letta | SOAT |
| --- | --- | --- |
| Type | agent infrastructure | agent infrastructure |
| License | Apache-2.0 | Apache-2.0 |
| Deployment | self-hosted or managed | self-hosted |
| Native capabilities | 7 of 15 | 12 of 15 |
| Last verified | 2026-08-14 | 2026-08-14 |

## Where each one leads

- **Letta** is native where SOAT is not: channels, skill learning.
- **SOAT** is native where Letta is not: identity & governance, observability, data & secrets, evaluation, multi-tenancy, declarative deployment, versioning & rollout.

## What Letta is

Open-source server for stateful LLM agents (formerly MemGPT) that persists agent state, memory blocks, and archival passages in PostgreSQL with pgvector, exposed over a REST API and SDKs. Deployable via Docker or usable as a hosted service, with agent state surviving context-window eviction. [Letta documentation](https://docs.letta.com/).

## Capability by capability

### Agent runtime

_Agent loop, sessions, and generation lifecycle._

- **Letta: Native.** The Letta server runs the agent loop and persists all agent and message state in PostgreSQL, exposed through a REST API. ([source](https://docs.letta.com/v1-sdk/docker))
- **SOAT: Native.** Agents, sessions, chats, and generations with full lifecycle tracking. ([source](https://soat.ttoss.dev/docs/modules/agents))

### Orchestration

_Multi-step pipelines, workflows, and triggers._

- **Letta: Native.** Multi-agent coordination via shared memory blocks and message-passing tools, plus subagents and Schedules for recurring tasks. ([source](https://docs.letta.com/))
- **SOAT: Native.** DAG orchestrations, workflow state machines, durable tasks, and triggers (manual, webhook, schedule). ([source](https://soat.ttoss.dev/docs/modules/orchestrations))

### Knowledge & memory

_Documents, embeddings, semantic search, and recall._

- **Letta: Native.** Agents have editable in-context memory blocks plus archival memory with hybrid semantic and full-text search over pgvector. ([source](https://docs.letta.com/guides/agents/archival-search/))
- **SOAT: Native.** Documents with per-chunk embeddings, named memories, unified semantic search, and ingestion rules for PDFs, images, and audio. ([source](https://soat.ttoss.dev/docs/modules/knowledge))

### Tools & integration

_Tool calling, MCP, providers, and webhooks._

- **Letta: Native.** Supports server tools, client-side tools, and MCP servers registered over streamable HTTP, SSE, or stdio transports. ([source](https://docs.letta.com/guides/agents/tool-execution-mcp/))
- **SOAT: Native.** HTTP, MCP, client, and agent-to-agent tools; model routes with failover; webhooks; any LLM provider. ([source](https://soat.ttoss.dev/docs/modules/tools))

### Identity & governance

_IAM, guardrails, approvals, quotas, and audit._

- **Letta: Partial.** Self-hosted access control is a single shared server password; the open-source server documents no role-based access control, approvals, or audit log. ([source](https://docs.letta.com/v1-sdk/docker))
- **SOAT: Native.** AWS-inspired IAM, actors, scoped API keys, guardrails, human approvals, quotas, and an append-only audit log. ([source](https://soat.ttoss.dev/docs/modules/iam))

### Observability

_Traces, activity, usage, and failure queues._

- **Letta: Partial.** The Agent Development Environment surfaces agent reasoning, tool usage, and state in real time, but there is no documented cost accounting or failure queue. ([source](https://docs.letta.com/guides/ade/tools/))
- **SOAT: Native.** Traces of every tool call and model response, activity feed, usage/cost tracking, and an exceptions queue. ([source](https://soat.ttoss.dev/docs/modules/traces))

### Data & secrets

_File storage and encrypted secrets._

- **Letta: Absent.** The document/file source system is deprecated and disabled, and no encrypted secrets store is provided; credentials are server environment variables.
- **SOAT: Native.** File storage over local/S3/GCS backends and encrypted secrets storage. ([source](https://soat.ttoss.dev/docs/modules/files))

### Evaluation

_Datasets, scorers, and eval-gated improvement._

- **Letta: Absent.** No datasets, scorers, or evaluation-run functionality is documented.
- **SOAT: Native.** Datasets, scorers, and scored runs; eval-gated promotion of agent versions. ([source](https://soat.ttoss.dev/docs/modules/evaluations))

### Channels

_Built-in gateways to messaging platforms and UIs._

- **Letta: Native.** Built-in channel adapters connect agents to Telegram, Slack, Discord, WhatsApp, and Signal, plus a web and desktop chat UI. ([source](https://docs.letta.com/configuration/channels))
- **SOAT: Absent.** Surfaces are REST, MCP, CLI, and SDK — no built-in gateways to messaging platforms like Slack, WhatsApp, or Telegram.

### Code execution

_Sandboxed code or terminal runtimes for agents._

- **Letta: Partial.** Custom server tools execute in an E2B sandbox requiring external API credentials; there is no general-purpose code interpreter or terminal runtime built in. ([source](https://docs.letta.com/v1-sdk/docker))
- **SOAT: Absent.** Tool types are HTTP, MCP, client, and agent-to-agent — no built-in sandboxed code or terminal runtime.

### Human-in-the-loop

_Pausing a run for human approval, then resuming it._

- **Letta: Native.** Tools marked requires_approval halt the agent and emit an approval request with tool name and arguments; approving executes and resumes, denying returns an error the agent can work against. ([source](https://docs.letta.com/guides/agents/human-in-the-loop/))
- **SOAT: Native.** Approvals are a first-class human-decision queue with frozen evidence, and guardrails classify each tool call so risky actions pause for a decision. ([source](https://soat.ttoss.dev/docs/modules/approvals))

### Multi-tenancy

_Projects or workspaces scoping resources and permissions._

- **Letta: Partial.** Identity objects and agent tags associate agents with end users, but the open-source server documents no org or project permission boundary and warns against exposing it to untrusted clients. ([source](https://docs.letta.com/self-hosting))
- **SOAT: Native.** Projects are multi-tenant namespaces scoping every resource, with IAM policies and quotas enforced per project. ([source](https://soat.ttoss.dev/docs/modules/projects))

### Declarative deployment

_Templates that provision agent resources as one stack._

- **Letta: Via plugin.** Declarative fleet management with version-controlled YAML comes from lettactl, a community-built CLI listed under community guides rather than a first-party feature. ([source](https://docs.letta.com/guides/community/lettactl/))
- **SOAT: Native.** Formations provision providers, memories, tools, agents, orchestrations, and webhooks from one template, resolving refs into a dependency graph with tracked operations. ([source](https://soat.ttoss.dev/docs/modules/formations))

### Versioning & rollout

_Agent versions, canary rollout, gated promotion._

- **Letta: Via plugin.** Official template versioning with migrate and rollback is labeled cloud-only and deprecated, so self-hosted rollout control comes from the community lettactl tool. ([source](https://docs.letta.com/api/resources/templates/))
- **SOAT: Native.** Every config change is archived as an append-only agent version, with canary rollout to a slice of traffic and eval-gated promotion. ([source](https://soat.ttoss.dev/docs/tutorials/agent-versioning-and-canary-rollout))

### Skill learning

_Agents authoring reusable skills from their own experience._

- **Letta: Native.** Agents have a built-in skill creator and write skills into their own git-backed memory filesystem, persisting them as part of agent identity across agent, project, and computer scopes. ([source](https://docs.letta.com/letta-agent/skills))
- **SOAT: Absent.** Memories and knowledge store retrievable context, but agents do not author or refine reusable skills from their own experience.

## How this is rated

Each rating comes from the public documentation linked beside it: **Native** is built in, **Via plugin** needs an add-on, **Partial** covers part of the capability, **Absent** is not offered. Every solution side by side is on the [benchmark](/benchmark). A rating that is out of date is a bug: [open an issue](https://github.com/ttoss/soat/issues).