Comparison of Prompt Flow, Semantic Kernel, and LangChain for AI development


The world of AI is moving super fast! It's like we're on a speedy train, watching the landscape of artificial intelligence change and grow every day. With all this growth, we've got some cool tools popping up to help us develop even smarter large language model (LLM) apps powered by generative AI.

Recently, I looked into the options within Azure, and as always there is more than one option. I started my journey in the world of LLM app development using LangChain. I then came across Prompt Flow and Semantic Kernel (SK). These are pretty much the three big players when it comes to LLM app development. Think of them as the superheroes of the LLM app development world, each with their own special powers.

But why do we have so many of these tools, and why do they seem to be doing the same thing? Well, even though they aim to make applications that are smarter and more helpful, each one has its own unique functionalities.

Let's dive in and explore what makes LangChain, Semantic Kernel, and Prompt Flow stand out in the bustling world of AI. It's going to be a fun ride, so buckle up!

Introduction to LangChain

LangChain is a framework that simplifies integrating LLM capabilities into your application. It supports models by OpenAI, Cohere, HuggingFace, Anthropic and many more. The essence of LangChain is captured in its name, which combines "Lang" (short for language) with "Chain," reflecting the framework's core functionality of linking various components to harness LLMs for creating sophisticated language-based applications.

The framework is built to support a wide array of systems, tools, and services, positioning LangChain as a versatile and comprehensive solution for developing applications that leverage language models. It provides developers with a suite of features for tasks like document handling, code generation, data analysis, debugging, and integrating with databases and various data sources.


  • Accessible Learning Curve: Easy for beginners to grasp and start using quickly.

  • Comprehensive Features: Packed with out-of-the-box plugins for a wide range of AI applications.

  • Ideal for Prototyping: Encourages quick experimentation and real-world application testing.

  • Consistent Updates: The community around LangChain is active, and the framework is regularly updated to incorporate the latest developments in LLMs and best practices in AI.


  • Documentation Variability: Can be inconsistent, with some documentation being outdated or unclear.

  • Overcomplication Concerns: Sometimes seen as adding unnecessary complexity to simpler tasks.

  • Production Reluctance: Due to its expansive nature and frequent updates, some developers may be cautious about using LangChain in production environments.

For those interested in exploring LangChain further, extensive documentation is available to help you dive in. Additionally, the project's GitHub repository offers a collection of example code, demonstrating how to build applications using LangChain effectively.


Introduction to Semantic Kernel (SK)

Semantic Kernel is an open-source SDK from Microsoft that makes it easy to build AI agents that can interact with a wide range of LLMs as well as call existing application functions. It is available in Python, C#, and Java.

Semantic Kernel revolves around a Kernel that handles events using plugins and functions to complete a task. It also includes a Planner that can automatically decide which plugins and functions to use given a prompt.


  • Microsoft Support and .NET Integration: Offers reliability and seamless integration within the Microsoft ecosystem.

  • Streamlined Prompt Management: Simplifies the creation and management of AI interactions.

  • Versatility in Application: Suitable for both experimentation and deployment in real-world scenarios.

  • Plugin Compatibility: Allows for easy transformation of SK plugins into OpenAI plugins.

  • Adaptation Requirement: Needs regular updates to keep pace with AI advancements.

  • Resource and Documentation Scarcity: Limited support materials can hinder learning and application.

  • Integration Learning Curve: Presents a steeper learning curve due to its unique approach.

  • Plugin and Extension Availability: Offers a narrower range of plugins and extensions compared to competitors.

To get started with SK, Microsoft has published a GitHub repo where you can find notebooks in both Python, C# and Java, along with pre-built functions and plugins. 


Semantic Kernel vs Langchain

Semantic Kernel is very similar to LangChain, however LangChain now has more features than Semantic Kernel in practical scenarios and has a far bigger community behind it. Choosing between LangChain and Semantic Kernel depends on specific project requirements, preferred programming languages, and the desired level of integration and flexibility. LangChain is well-suited for projects that benefit from its wide range of out-of-the-box tools and active developer engagement. In contrast, Semantic Kernel may be the better choice for projects within the .NET ecosystem or those that require a lightweight framework with strong planning and memory management capabilities​.


Introduction to Prompt Flow

Image from Azure platform

Prompt Flow is a toolkit designed to make the development of AI apps powered by Large Language Models (LLMs) more streamlined from prototyping, testing, evaluation, deployment and monitoring. It makes prompt engineering much easier and enables developers to build high-quality LLM applications.

It's available as an open-source project complete with its own SDK and Visual Studio Code extension. However, its static nature means we often need something more - like LangChain or Semantic Kernel - to bring dynamic orchestration into the mix.

For instance, in a customer service scenario, a static system might provide generic answers to frequent questions without considering the specific details of a customer's issue. On the other hand, a dynamic orchestration powered by LangChain or Semantic Kernel would analyse the customer's query in real-time, pull specific data related to their account or issue from a claims database, and generate a response tailored to their unique situation.

Example of Dynamic Orchestration:
  • Without Dynamic Orchestration:

Customer: "I'm having issues with my product warranty claim."

Response: "Here's our warranty policy [link]. Please follow the steps mentioned for claims."


  • With Dynamic Orchestration (LangChain/Semantic Kernel):

Customer: "I'm having issues with my product warranty claim."

AI System: Analyses the query, identifies the product and customer account from the database, checks the status of the warranty claim.

Response: "We see that your claim for [Product Name] is currently under review. It was submitted on [Date], and the average processing time is [X] days. You'll receive an update by [Estimated Date]."



  • Enhanced Coherence: Ensures AI outputs are both coherent and relevant.

  • Improved Control: Allows users to direct conversations or content generation towards specific goals.

  • Flexibility: Adaptable across various applications, from creative writing to solving technical issues.

  • Orchestrated Executable Flows: Simplifies complex workflows through a visual graph, enhancing AI output effectiveness.

  • Enhanced Debugging and Collaboration: Facilitates teamwork and iterative improvements on executable flows.

  • Dynamic Prompt Variation: Enables experimentation with prompt variants to optimise AI interactions.

  • One-click deployment: Easy to deploy the application to a real-time endpoint


  • Complexity in Design: Demands careful planning and understanding of AI model interpretations.

  • Potential for Derailment: Risks off-topic or irrelevant AI responses without proper management.

To get started with Promptflow, have a look at samples of prompt flow and explore the step-by-step tutorials.


Semantic Kernel or LangChain in PromptFlow

The good news is that it is possible to integrate LangChain and semantic kernel into prompt flow to build a powerful ai system.

LangChain Integration: By incorporating LangChain into PromptFlow, you can leverage its modular approach to customize and extend the AI’s abilities. LangChain supports a broad range of language models and tools, enabling the creation of complex, multi-step processes that can adapt to various tasks and user needs. For example, a content creation platform can utilise LangChain to dynamically chain together processes for researching, drafting, and refining written content, based on user prompts and feedback.

Semantic Kernel Integration: Semantic Kernel's integration brings structured decision-making and AI-driven task automation into Prompt Flow. It allows for the creation of intelligent agents that can understand context, make decisions, and execute tasks by interacting with databases, APIs, and other system components. An eCommerce support chatbot enhanced with Semantic Kernel, for instance, could automatically handle inquiries, access user purchase histories, initiate returns, or escalate complex issues to human agents, all within a seamless conversation flow.

Real-World Applications: Case Studies

To truly grasp the utility of these tools, let's consider two hypothetical scenarios: an AI-driven customer support system and a content generation platform for digital marketing. These examples illustrate how Prompt Flow, LangChain, and Semantic Kernel can be applied to solve real-world problems, from improving customer service interactions to automating content creation across various platforms.

Case Study 1: Automated Customer Support

Scenario: A tech company wants to improve its customer support system by integrating an AI that can handle inquiries through chat.

Prompt Flow Application: The company designs a series of prompts to guide the AI in handling common customer issues, such as password resets or troubleshooting service outages. This ensures that the AI maintains coherence and stays on topic throughout the interaction. However, the static nature of prompt flow might limit the AI's ability to handle unexpected or complex queries without manual intervention or reprogramming.

LangChain Application: By utilising LangChain, the company chains together different tasks like understanding the customer's issue, searching the knowledge base for solutions, and generating human-like responses. LangChain's modularity allows the AI to adapt to a wide range of inquiries by dynamically selecting the appropriate chain of tasks for each situation. This flexibility makes the customer support system more robust and capable of handling complex issues without human intervention.

Semantic Kernel Application: The company uses SK to build an AI agent that can interact with both the customer and the company's systems. SK's event handling and automatic decision-making capabilities allow the AI to understand the context of customer inquiries, decide the best course of action, and even perform tasks like resetting passwords or initiating service diagnostics. The integration with .NET and support for various LLMs make SK an ideal choice for companies already invested in Microsoft technologies.

Case Study 2: Content Generation for Digital Marketing

Scenario: A digital marketing agency wants to automate the creation of content for various platforms, requiring nuanced tone and style adjustments.

Prompt Flow Application: The agency uses a detailed prompt flow to guide the AI in generating content that aligns with different brand voices and marketing goals. This approach ensures that each piece of content is coherent and on-brand. However, the need for extensive and detailed prompt flows for each brand voice and style can become labour-intensive.

LangChain Application: The agency leverages LangChain to chain together tasks for analysing the target audience, generating content ideas, and writing drafts in specified tones and styles. LangChain's ability to integrate different LLM capabilities and plugins allows for more dynamic content generation, making it easier to adapt to various brands and marketing strategies without extensive manual input.

Semantic Kernel Application: By utilising SK, the agency creates an AI agent capable of understanding the nuances of different brand voices and marketing objectives. The Kernel's event handling and Planner's decision-making processes enable the AI to automatically adjust its writing style and content focus based on the brand's guidelines and the campaign's goals. SK's clean prompt implementation and plugin system allow for seamless integration into the agency's existing workflows.



Prompt Flow is excellent for maintaining coherence and control in predictable scenarios but may require adjustments for complex or unexpected inquiries. LangChain excels in applications requiring flexibility and the integration of multiple tasks or data sources, making it ideal for dynamic and complex scenarios. Semantic Kernel offers robust event handling and decision-making capabilities, suitable for scenarios where integration with existing systems and nuanced control over AI behavior are critical.

Choosing between Prompt Flow, LangChain, and Semantic Kernel depends on the specific needs and challenges of your project. Whether it's the flexibility and orchestration capabilities of LangChain, the integration and streamlined management offered by Semantic Kernel, or the coherent and controlled environment facilitated by Prompt Flow, each tool has its place in the AI development toolkit. Understanding their strengths and limitations is key to leveraging the right tool for the right task in the ever-evolving world of artificial intelligence.


Gavita Regunath


Gavita Regunath