 <p>This is reason :</p> <p>Grails is a mix of many frameworks, spring, hibernate etc. All the frameworks are included and you need them as they are the baseline of grails every grails application comes with many plugins by default (look into your BuildConfig.groovy): cache, asset, scaffolding etc. Every plugin has their own dependencies like classes, jars, js etc All of them add up.</p> <p>Solution: a war and also a jar are just containers. Open them with your favorite unzip program and check.</p> <p>You can remove that by using following command</p> <pre><code>grails war -nojars </code></pre> <p>Note: It will build a war without WEB-INF/lib jars. But you have to provide them to your webserver before deployment. </p> <p>reference: <a href="http://mrhaki.blogspot.in/2009/05/create-much-smaller-grails-war-file.html" rel="nofollow">http://mrhaki.blogspot.in/2009/05/create-much-smaller-grails-war-file.html</a></p> <p>OR</p> <p>If you want remove the perticular jar files then you can use below config </p> <p>Add to your BuildConfig.groovy:</p> <pre><code>grails.war.resources = { stagingDir -&gt; delete(file:"${stagingDir}/WEB-INF/lib/whatever.jar") } </code></pre>