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Letta vs Semantic Kernel

LettaSemantic Kernel

Bottom line: Letta for teams that need persistent agent memory; Semantic Kernel for enterprise .NET development teams.

LettaLetta

Stateful AI agents with long-term memory (formerly MemGPT).

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Semantic KernelSemantic Kernel

Microsoft's enterprise SDK for orchestrating LLMs, plugins, and agents.

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Votes00
PricingFreemiumFree
CategoryAgent FrameworksAgent Frameworks
Tags
agentsmemoryopen-sourcestateful-agentsllm-framework
llm-frameworkagentsopen-sourcemicrosoftdotnet
Best for
  • Teams that need persistent agent memory
  • Builders of long-running assistants
  • Researchers exploring stateful agents
  • Enterprise .NET development teams
  • Microsoft/Azure-aligned organizations
  • Developers adding AI to existing apps
Pros
  • Purpose-built for the agent memory problem
  • Strong research pedigree (MemGPT paper)
  • OS-style tiered memory persists across sessions
  • Open-source core, free to self-host
  • Managed Letta Cloud with free and paid tiers
  • First-class C#/.NET support, rare among AI frameworks
  • Free and open source
  • Enterprise features: type safety, DI, telemetry
  • Multi-language (C#, Python, Java)
  • Backed by Microsoft with clear Azure integration
Cons
  • Narrower than general agent frameworks
  • Often used alongside other tooling, not a full stack
  • Renamed from MemGPT, some older docs use old name
  • Cloud pricing and tiers still evolving
  • Python-focused
  • Strategic focus shifting to Microsoft Agent Framework
  • Concepts like planners have changed across versions
  • Python support historically trailed .NET
  • Migration planning needed for long-term projects
  • Less multi-agent focus than AutoGen lineage

Comparison generated from each tool's listing. Add or remove tools above to change it.