# Migrate from previous KCL versions
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This topic explains how to migrate from previous versions of the Kinesis Client Library (KCL). 

## What's new in KCL 3.0?
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Kinesis Client Library (KCL) 3.0 introduces several major enhancements compared to previous versions:
+  It lowers compute costs for consumer applications by automatically redistributing the work from over-utilized workers to under-utilized workers in the consumer application fleet. This new load balancing algorithm ensures the evenly distributed CPU utilization across workers and removes the need to over-provision workers.
+  It reduces the DynamoDB cost associated with KCL by optimizing read operations on the lease table.
+ It minimizes reprocessing of data when leases are reassigned to another worker by allowing the current worker to complete checkpointing the records that it has processed.
+  It uses Amazon SDK for Java 2.x for improved performance and security features, fully removing the dependency on Amazon SDK for Java 1.x.

For more information, see [KCL 3.0 release note](https://github.com/awslabs/amazon-kinesis-client/blob/master/CHANGELOG.md).

**Topics**
+ [What's new in KCL 3.0?](#kcl-migration-new-3-0)
+ [Migrate from KCL 2.x to KCL 3.x](kcl-migration-from-2-3.md)
+ [Roll back to the previous KCL version](kcl-migration-rollback.md)
+ [Roll forward to KCL 3.x after a rollback](kcl-migration-rollforward.md)
+ [Best practices for the lease table with provisioned capacity mode](kcl-migration-lease-table.md)
+ [Migrating from KCL 1.x to KCL 3.x](kcl-migration-1-3.md)