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LangChain v0.2 is coming soon! Preview the new docs [here](/v0.2/docs/introduction/).

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*   [Get started](/v0.1/docs/get_started/)
    
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*   [LangChain Expression Language](/v0.1/docs/expression_language/)
    
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*   [](/v0.1/)
*   Guides

Guides
======

Design guides for key parts of the development process

[

📄️ Debugging
-------------

If you're building with LLMs, at some point something will break, and you'll need to debug.

](/v0.1/docs/guides/debugging/)

[

🗃️ Deployment
--------------

2 items

](/v0.1/docs/guides/deployment/)

[

🗃️ Evaluation
--------------

4 items

](/v0.1/docs/guides/evaluation/)

[

📄️ Extending LangChain.js
--------------------------

Extending LangChain's base abstractions, whether you're planning to contribute back to the open-source repo or build a bespoke internal integration, is encouraged.

](/v0.1/docs/guides/extending_langchain/)

[

📄️ Fallbacks
-------------

When working with language models, you may often encounter issues from the underlying APIs, e.g. rate limits or downtime.

](/v0.1/docs/guides/fallbacks/)

[

📄️ LangSmith Walkthrough
-------------------------

LangChain makes it easy to prototype LLM applications and Agents. However, delivering LLM applications to production can be deceptively difficult. You will have to iterate on your prompts, chains, and other components to build a high-quality product.

](/v0.1/docs/guides/langsmith_evaluation/)

[

📄️ Migrating to 0.1
--------------------

If you're still using the pre 0.1 version of LangChain, but want to upgrade to the latest version, we've created a script that can handle almost every aspect of the migration for you.

](/v0.1/docs/guides/migrating/)

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