Copilot SDK vs Semantic Kernel
Which should you use? A side-by-side look at what each one does, who it suits, what it costs, how hard it is to set up, and where each falls short.
Open source · MIT
SDK for embedding GitHub Copilot's agent runtime into your own apps, in several languages.
Open source · MIT
Open-source SDK for building AI agents and multi-agent apps in Python, .NET and Java.
The short answer
Choose Copilot SDK if you need…
- Developers who want to add agent features to an existing app or service
- Teams building in one of the listed languages (Node.js/TypeScript, Python, Go, .NET, Java, Rust)
- Projects that want to avoid writing their own agent orchestration from scratch
Choose Semantic Kernel if you need…
- Developers already using Azure OpenAI or OpenAI who want a structured SDK for agents
- Teams working in .NET, Python or Java who want one framework across languages
- Projects that need plugins built from native code, prompt templates, OpenAPI specs or MCP
- Existing Semantic Kernel users maintaining or migrating older code
Side-by-side
| Copilot SDK | Semantic Kernel | |
|---|---|---|
| Type | Library | Library |
| Price | Free and open source | Free and open source |
| Licence | MIT | MIT |
| GitHub stars | 10.6k | 28.7k |
| Setup difficulty | Intermediate | Intermediate |
| How you get it | Install with a package manager | Install with a package manager |
| Main language | Java | C# |
| Last code update | 5 days ago | 4 days ago |
What each one is
Copilot SDK
The Copilot SDK lets developers call the same agent engine that powers Copilot CLI from their own code. You define the agent's behavior, and Copilot handles planning, tool calls, and file edits. The README says it is available for Python, TypeScript/Node.js, Go, .NET, Java, and Rust, and that all SDKs talk to a Copilot CLI server over JSON-RPC.
Semantic Kernel
Semantic Kernel is a model-agnostic SDK from Microsoft that lets developers connect large language models (such as OpenAI or Azure OpenAI models) to their own apps, add tools and plugins, and orchestrate one or more AI agents. The README says it is now succeeded by Microsoft Agent Framework, so new projects should check that project first.
Best for
Copilot SDK
- Developers who want to add agent features to an existing app or service
- Teams building in one of the listed languages (Node.js/TypeScript, Python, Go, .NET, Java, Rust)
- Projects that want to avoid writing their own agent orchestration from scratch
Semantic Kernel
- Developers already using Azure OpenAI or OpenAI who want a structured SDK for agents
- Teams working in .NET, Python or Java who want one framework across languages
- Projects that need plugins built from native code, prompt templates, OpenAPI specs or MCP
- Existing Semantic Kernel users maintaining or migrating older code
Strengths
Copilot SDK
- Official SDKs for six languages, with package installs listed for each in the README
- Built on the same engine as Copilot CLI, per the README
- MIT licensed
Semantic Kernel
- Supports several models and providers, including OpenAI, Azure OpenAI, Hugging Face and NVidia, per the README
- Offers examples in Python and C# with matching quickstarts
- Permissive MIT license and a large public project with about 28,700 stars
Not ideal for
Copilot SDK
- People who only want to use Copilot interactively; the Copilot CLI or IDE tools fit that better
- Users without a GitHub Copilot subscription who do not plan to use BYOK, since the README says a subscription is required unless BYOK is used
- Languages outside the six listed SDKs
Semantic Kernel
- Non-programmers: it is a developer SDK and needs code to use, so no-code users should look elsewhere
- Teams starting fresh who want the newest path: the README directs users to Microsoft Agent Framework as the successor
- Simple scripts that only need one direct API call, where an SDK adds more structure than needed
Trade-offs
Copilot SDK
- The README says a GitHub Copilot subscription is required unless you use BYOK
- For Go, Java, and Rust the Copilot CLI must be installed separately or available on PATH
- The README is in transition: it notes the project is becoming Microsoft Copilot SDK and some names may still say GitHub
Semantic Kernel
- The README states the project is succeeded by Microsoft Agent Framework, so long-term direction may point elsewhere
- Quickstarts assume Azure or OpenAI credentials and a configured environment, so setup needs some engineering work
- Java support is pointed to a separate build guide rather than documented here
Getting started
Copilot SDK
Node.js / TypeScript
npm install @github/copilot-sdkPython
pip install github-copilot-sdkSemantic Kernel
Set Azure OpenAI API key
export AZURE_OPENAI_API_KEY=AAA....Set OpenAI API key (alternative)
export OPENAI_API_KEY=sk-...Frequently asked questions
What is the difference between Copilot SDK and Semantic Kernel?
Copilot SDK: SDK for embedding GitHub Copilot's agent runtime into your own apps, in several languages. Semantic Kernel: Open-source SDK for building AI agents and multi-agent apps in Python, .NET and Java. Copilot SDK suits developers who want to add agent features to an existing app or service, while Semantic Kernel suits developers already using azure openai or openai who want a structured sdk for agents.
Are Copilot SDK and Semantic Kernel free?
Copilot SDK: Free and open source. Semantic Kernel: Free and open source.
Is Copilot SDK or Semantic Kernel more popular?
Semantic Kernel has more GitHub stars (28.7k) than Copilot SDK (10.6k). Popularity isn't the same as fit — check which one matches your use case above.
What are other alternatives to Copilot SDK and Semantic Kernel?
Other options people compare them with include LangChain, LlamaIndex, Microsoft Agent Framework, OpenAI Agents SDK, Semantica.
Keep comparing
Built from our catalogue entries for both products: open-source details come from each project's README (AI-assisted, refreshed weekly) and GitHub data; AI-tool details are editorial. Spotted something wrong? Let us know from either product's page.