Apache Commons Codec

Apache Commons Codec (TM) software provides implementations of common encoders and decoders such as Base64, Hex, Phonetic and URLs.


Codec was formed as an attempt to focus development effort on one definitive implementation of the Base64 encoder. At the time of Codec's proposal, there were approximately 34 different Java classes that dealt with Base64 encoding spread over the Foundation's CVS repository. Developers in the Jakarta Tomcat project had implemented an original version of the Base64 codec which had been copied by the Commons HttpClient and Apache XML project's XML-RPC subproject. After almost one year, the two forked versions of Base64 had significantly diverged from one another. XML-RPC had applied numerous fixes and patches which were not applied to the Commons HttpClient Base64. Different subprojects had differing implementations at various levels of compliance with the RFC 2045.

Out of that confusing duplication of effort sprang this simple attempt to encourage code reuse among various projects. While this package contains a abstract framework for the creation of encoders and decoders, Codec itself is primarily focused on providing functional utilities for working with common encodings.


An overview of the functionality is provided in the user guide. Various project reports are also available.

The JavaDoc API documents are available online:

The subversion repository can be browsed.


  • Codec 1.9 requires Java 1.6
  • Codec 1.8 requires Java 1.6
  • Codec 1.7 requires Java 1.6
  • Codec 1.6 requires Java 1.5
  • Codec 1.5 requires Java 1.4
  • Codec 1.4 requires Java 1.4

See the Download Page for the latest releases.

Upgrade notes are also available.

For previous releases, see the Apache Archive


The commons mailing lists act as the main support forum. The user list is suitable for most library usage queries. The dev list is intended for the development discussion. Please remember that the lists are shared between all commons components, so prefix your email by [codec].

Issues may be reported via ASF JIRA.