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Java and Android client for Flattr API
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Java Flattr Client build status

flattr4j is a free open source Java library for using the Flattr API and adding Flattr buttons to JSP web sites.

It primarily targets for business grade Flattr integration, e.g. on servers, web sites and full-featured desktop applications, but it can also be used on Android devices.

flattr4j is not endorsed by or affiliated with Flattr AB.

Important Note

Flattr is currently changing its API. Because of that, some of the flattr4j calls are failing or not delivering the expected results.

Are you getting a "Received fatal alert: handshake_failure" exception? OpenJDK does not seem to support any of the Flattr server's cipher suites. Use the Oracle JDK instead!


  • Lightweight and easy to use
  • Covers the entire Flattr API
  • Also runs on Android
  • JSP tag library for inserting static and javascript Flattr buttons
  • Helps through the OAuth authentication process at Flattr, no OAuth knowledge is needed
  • With Maven and Spring support
  • Spring Social provider available (currently beta)




flattr4j is open source software. The source code is distributed under the terms of GNU General Public License Version 3, GNU Lesser General Public License Version 3, Apache License 2.0.

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