diff --git a/extensions/database/pom.xml b/extensions/database/pom.xml
index 653c22559..fe1ca7919 100644
--- a/extensions/database/pom.xml
+++ b/extensions/database/pom.xml
@@ -24,72 +24,23 @@
     <testSourceDirectory>tests/src</testSourceDirectory>
     <outputDirectory>module/MOD-INF/classes</outputDirectory>
     <plugins>
-      <plugin>
-        <groupId>org.codehaus.mojo</groupId>
-        <artifactId>build-helper-maven-plugin</artifactId>
-        <version>3.2.0</version>
-        <executions>
-          <execution>
-            <phase>generate-sources</phase>
-            <goals>
-              <goal>add-source</goal>
-            </goals>
-            <configuration>
-              <sources>
-                <source>src</source>
-              </sources>
-            </configuration>
-          </execution>
-        </executions>
-      </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.8.1</version>
-        <configuration>
-          <source>${java.minversion}</source>
-          <target>${java.minversion}</target>
-          <encoding>UTF-8</encoding>
-          <showDeprecation>false</showDeprecation>
-        </configuration>
-      </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-resources-plugin</artifactId>
-        <version>3.2.0</version>
-        <configuration>
-          <encoding>UTF-8</encoding>
-        </configuration>
-      </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
-        <version>2.22.2</version>
+	<version>${surefire.version}</version>
         <configuration>
           <suiteXmlFiles>
             <suiteXmlFile>tests/conf/tests.xml</suiteXmlFile>
           </suiteXmlFiles>
         </configuration>
       </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-clean-plugin</artifactId>
-        <version>3.1.0</version>
-        <configuration>
-          <filesets>
-            <fileset>
-              <directory>module/MOD-INF/lib</directory>
-            </fileset>
-          </filesets>
-        </configuration>
-      </plugin>
     </plugins>
     <pluginManagement>
       <plugins>
         <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-dependency-plugin</artifactId>
-            <version>3.2.0</version>
+	    <version>${maven-dependency-plugin.version}</version>
             <executions>
                 <execution>
                 <phase>compile</phase>
@@ -116,8 +67,8 @@
     </dependency>
     <dependency>
       <groupId>javax.servlet</groupId>
-      <artifactId>servlet-api</artifactId>
-      <version>2.5</version>
+      <artifactId>javax.servlet-api</artifactId>
+      <version>${servlet-api.version}</version>
       <scope>provided</scope>
     </dependency>
     <dependency>
@@ -128,7 +79,7 @@
     <dependency>
       <groupId>org.apache.httpcomponents</groupId>
       <artifactId>httpclient</artifactId>
-      <version>4.5.13</version>
+      <version>${httpclient.version}</version>
     </dependency>
     <dependency>
       <groupId>com.google.http-client</groupId>
@@ -143,7 +94,7 @@
     <dependency>
       <groupId>org.jasypt</groupId>
       <artifactId>jasypt</artifactId>
-      <version>1.9.3</version>
+      <version>${jasypt.version}</version>
     </dependency>
     <dependency>
       <groupId>org.mariadb.jdbc</groupId>
@@ -169,27 +120,26 @@
     <dependency>
       <groupId>org.apache.commons</groupId>
       <artifactId>commons-lang3</artifactId>
-      <version>3.12.0</version>
+      <version>${commons-lang3.version}</version>
     </dependency>
-    
     <dependency>
-	    <groupId>org.owasp.encoder</groupId>
-	    <artifactId>encoder</artifactId>
-	    <version>1.2.3</version>
-	</dependency>
-
+      <groupId>org.owasp.encoder</groupId>
+      <artifactId>encoder</artifactId>
+      <version>${owasp-encoder.version}</version>
+    </dependency>
   
+    <!-- test dependencies -->
 
     <dependency>
       <groupId>org.testng</groupId>
       <artifactId>testng</artifactId>
-      <version>7.4.0</version>
+      <version>${testng.version}</version>
       <scope>test</scope>
     </dependency>
     <dependency>
       <groupId>org.mockito</groupId>
       <artifactId>mockito-core</artifactId>
-      <version>4.1.0</version>
+      <version>${mockito.version}</version>
       <scope>test</scope>
     </dependency>
 
diff --git a/extensions/gdata/pom.xml b/extensions/gdata/pom.xml
index 61fc95614..d457b6a23 100644
--- a/extensions/gdata/pom.xml
+++ b/extensions/gdata/pom.xml
@@ -24,43 +24,6 @@
     <testSourceDirectory>tests/src</testSourceDirectory>
     <outputDirectory>module/MOD-INF/classes</outputDirectory>
     <plugins>
-      <plugin>
-        <groupId>org.codehaus.mojo</groupId>
-        <artifactId>build-helper-maven-plugin</artifactId>
-        <version>3.2.0</version>
-        <executions>
-          <execution>
-            <phase>generate-sources</phase>
-            <goals>
-              <goal>add-source</goal>
-            </goals>
-            <configuration>
-              <sources>
-                <source>src</source>
-              </sources>
-            </configuration>
-          </execution>
-        </executions>
-      </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.8.1</version>
-        <configuration>
-          <source>${java.minversion}</source>
-          <target>${java.minversion}</target>
-          <encoding>UTF-8</encoding>
-          <showDeprecation>false</showDeprecation>
-        </configuration>
-      </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-resources-plugin</artifactId>
-        <version>3.2.0</version>
-        <configuration>
-          <encoding>UTF-8</encoding>
-        </configuration>
-      </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
@@ -71,25 +34,13 @@
           </suiteXmlFiles>
         </configuration>
       </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-clean-plugin</artifactId>
-        <version>3.1.0</version>
-        <configuration>
-          <filesets>
-            <fileset>
-              <directory>module/MOD-INF/lib</directory>
-            </fileset>
-          </filesets>
-        </configuration>
-      </plugin>
     </plugins>
     <pluginManagement>
       <plugins>
         <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-dependency-plugin</artifactId>
-            <version>3.2.0</version>
+	    <version>${maven-dependency-plugin.version}</version>
             <executions>
                 <execution>
                 <phase>compile</phase>
@@ -117,14 +68,14 @@
     </dependency>
     <dependency>
       <groupId>javax.servlet</groupId>
-      <artifactId>servlet-api</artifactId>
-      <version>2.5</version>
+      <artifactId>javax.servlet-api</artifactId>
+      <version>${servlet-api.version}</version>
       <scope>provided</scope>
     </dependency>
     <dependency>
       <groupId>org.apache.httpcomponents</groupId>
       <artifactId>httpclient</artifactId>
-      <version>4.5.13</version>
+      <version>${httpclient.version}</version>
     </dependency>
     <dependency>
       <groupId>com.google.apis</groupId>
@@ -142,16 +93,19 @@
       <version>${jackson.version}</version>
       <scope>provided</scope>
     </dependency>
+
+    <!-- test dependencies -->
+
     <dependency>
       <groupId>org.testng</groupId>
       <artifactId>testng</artifactId>
-      <version>7.4.0</version>
+      <version>${testng.version}</version>
       <scope>test</scope>
     </dependency>
     <dependency>
       <groupId>org.mockito</groupId>
       <artifactId>mockito-core</artifactId>
-      <version>4.1.0</version>
+      <version>${mockito.version}</version>
       <scope>test</scope>
     </dependency>
 
diff --git a/extensions/jython/pom.xml b/extensions/jython/pom.xml
index b1e8e3f06..39726bf39 100644
--- a/extensions/jython/pom.xml
+++ b/extensions/jython/pom.xml
@@ -26,43 +26,6 @@
     <testSourceDirectory>tests/src</testSourceDirectory>
     <outputDirectory>module/MOD-INF/classes</outputDirectory>
     <plugins>
-      <plugin>
-        <groupId>org.codehaus.mojo</groupId>
-        <artifactId>build-helper-maven-plugin</artifactId>
-        <version>3.2.0</version>
-        <executions>
-          <execution>
-            <phase>generate-sources</phase>
-            <goals>
-              <goal>add-source</goal>
-            </goals>
-            <configuration>
-              <sources>
-                <source>src</source>
-              </sources>
-            </configuration>
-          </execution>
-        </executions>
-      </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.8.1</version>
-        <configuration>
-          <source>${java.minversion}</source>
-          <target>${java.minversion}</target>
-          <encoding>UTF-8</encoding>
-          <showDeprecation>false</showDeprecation>
-        </configuration>
-      </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-resources-plugin</artifactId>
-        <version>3.2.0</version>
-        <configuration>
-          <encoding>UTF-8</encoding>
-        </configuration>
-      </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
@@ -76,7 +39,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-dependency-plugin</artifactId>
-        <version>3.2.0</version>
+	<version>${maven-dependency-plugin.version}</version>
         <executions>
             <execution>
             <phase>compile</phase>
@@ -90,18 +53,6 @@
             </execution>
         </executions>
       </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-clean-plugin</artifactId>
-        <version>3.1.0</version>
-        <configuration>
-          <filesets>
-            <fileset>
-              <directory>module/MOD-INF/lib</directory>
-            </fileset>
-          </filesets>
-        </configuration>
-      </plugin>
      </plugins>
   </build>
 
@@ -114,8 +65,8 @@
     </dependency>
     <dependency>
       <groupId>javax.servlet</groupId>
-      <artifactId>servlet-api</artifactId>
-      <version>2.5</version>
+      <artifactId>javax.servlet-api</artifactId>
+      <version>${servlet-api.version}</version>
       <scope>provided</scope>
     </dependency>
     <dependency>
@@ -124,10 +75,12 @@
       <version>2.7.2</version>
     </dependency>
 
+    <!-- test dependencies -->
+
     <dependency>
       <groupId>org.testng</groupId>
       <artifactId>testng</artifactId>
-      <version>7.4.0</version>
+      <version>${testng.version}</version>
       <scope>test</scope>
     </dependency>
 
diff --git a/extensions/pc-axis/pom.xml b/extensions/pc-axis/pom.xml
index 47545ff0d..e4dedfb2f 100644
--- a/extensions/pc-axis/pom.xml
+++ b/extensions/pc-axis/pom.xml
@@ -24,43 +24,6 @@
     <testSourceDirectory>tests/src</testSourceDirectory>
     <outputDirectory>module/MOD-INF/classes</outputDirectory>
     <plugins>
-      <plugin>
-        <groupId>org.codehaus.mojo</groupId>
-        <artifactId>build-helper-maven-plugin</artifactId>
-        <version>3.2.0</version>
-        <executions>
-          <execution>
-            <phase>generate-sources</phase>
-            <goals>
-              <goal>add-source</goal>
-            </goals>
-            <configuration>
-              <sources>
-                <source>src</source>
-              </sources>
-            </configuration>
-          </execution>
-        </executions>
-      </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.8.1</version>
-        <configuration>
-          <source>${java.minversion}</source>
-          <target>${java.minversion}</target>
-          <encoding>UTF-8</encoding>
-          <showDeprecation>false</showDeprecation>
-        </configuration>
-      </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-resources-plugin</artifactId>
-        <version>3.2.0</version>
-        <configuration>
-          <encoding>UTF-8</encoding>
-        </configuration>
-      </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
@@ -72,7 +35,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-dependency-plugin</artifactId>
-        <version>3.2.0</version>
+	<version>${maven-dependency-plugin.version}</version>
         <executions>
             <execution>
             <phase>compile</phase>
@@ -86,18 +49,6 @@
             </execution>
         </executions>
       </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-clean-plugin</artifactId>
-        <version>3.1.0</version>
-        <configuration>
-          <filesets>
-            <fileset>
-              <directory>module/MOD-INF/lib</directory>
-            </fileset>
-          </filesets>
-        </configuration>
-      </plugin>
     </plugins>
   </build>
 
@@ -110,15 +61,15 @@
     </dependency>
     <dependency>
       <groupId>javax.servlet</groupId>
-      <artifactId>servlet-api</artifactId>
-      <version>2.5</version>
+      <artifactId>javax.servlet-api</artifactId>
+      <version>${servlet-api.version}</version>
       <scope>provided</scope>
     </dependency>
 
     <dependency>
       <groupId>org.testng</groupId>
       <artifactId>testng</artifactId>
-      <version>7.4.0</version>
+      <version>${testng.version}</version>
       <scope>test</scope>
     </dependency>
 
diff --git a/extensions/phonetic/pom.xml b/extensions/phonetic/pom.xml
index b7adeca3b..bcfdcfa52 100644
--- a/extensions/phonetic/pom.xml
+++ b/extensions/phonetic/pom.xml
@@ -26,43 +26,6 @@
     <testSourceDirectory>tests/src</testSourceDirectory>
     <outputDirectory>module/MOD-INF/classes</outputDirectory>
     <plugins>
-      <plugin>
-        <groupId>org.codehaus.mojo</groupId>
-        <artifactId>build-helper-maven-plugin</artifactId>
-        <version>3.2.0</version>
-        <executions>
-          <execution>
-            <phase>generate-sources</phase>
-            <goals>
-              <goal>add-source</goal>
-            </goals>
-            <configuration>
-              <sources>
-                <source>src</source>
-              </sources>
-            </configuration>
-          </execution>
-        </executions>
-      </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.8.1</version>
-        <configuration>
-          <source>${java.minversion}</source>
-          <target>${java.minversion}</target>
-          <encoding>UTF-8</encoding>
-          <showDeprecation>false</showDeprecation>
-        </configuration>
-      </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-resources-plugin</artifactId>
-        <version>3.2.0</version>
-        <configuration>
-          <encoding>UTF-8</encoding>
-        </configuration>
-      </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
@@ -76,7 +39,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-dependency-plugin</artifactId>
-        <version>3.2.0</version>
+	<version>${maven-dependency-plugin.version}</version>
         <executions>
             <execution>
             <phase>compile</phase>
@@ -90,18 +53,6 @@
             </execution>
         </executions>
       </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-clean-plugin</artifactId>
-        <version>3.1.0</version>
-        <configuration>
-          <filesets>
-            <fileset>
-              <directory>module/MOD-INF/lib</directory>
-            </fileset>
-          </filesets>
-        </configuration>
-      </plugin>
     </plugins>
   </build>
 
@@ -114,8 +65,8 @@
     </dependency>
     <dependency>
       <groupId>javax.servlet</groupId>
-      <artifactId>servlet-api</artifactId>
-      <version>2.5</version>
+      <artifactId>javax.servlet-api</artifactId>
+      <version>${servlet-api.version}</version>
       <scope>provided</scope>
     </dependency>
 
@@ -124,7 +75,7 @@
     <dependency>
       <groupId>org.testng</groupId>
       <artifactId>testng</artifactId>
-      <version>7.4.0</version>
+      <version>${testng.version}</version>
       <scope>test</scope>
     </dependency>
   </dependencies>
diff --git a/extensions/pom.xml b/extensions/pom.xml
index aa0f43dc8..6afdd2f3e 100644
--- a/extensions/pom.xml
+++ b/extensions/pom.xml
@@ -29,6 +29,24 @@
 
   <build>
     <plugins>
+      <plugin>
+        <groupId>org.codehaus.mojo</groupId>
+        <artifactId>build-helper-maven-plugin</artifactId>
+	<version>${build-helper-maven-plugin.version}</version>
+        <executions>
+          <execution>
+            <phase>generate-sources</phase>
+            <goals>
+              <goal>add-source</goal>
+            </goals>
+            <configuration>
+              <sources>
+                <source>src</source>
+              </sources>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
       <plugin>
         <groupId>org.jacoco</groupId>
         <artifactId>jacoco-maven-plugin</artifactId>
@@ -57,6 +75,18 @@
             </execution>
          </executions>
        </plugin>
+       <plugin>
+         <groupId>org.apache.maven.plugins</groupId>
+         <artifactId>maven-clean-plugin</artifactId>
+	 <version>${maven-clean-plugin.version}</version>
+         <configuration>
+           <filesets>
+             <fileset>
+               <directory>module/MOD-INF/lib</directory>
+             </fileset>
+           </filesets>
+         </configuration>
+       </plugin>
      </plugins>
    </build>
 </project>
diff --git a/extensions/sample/pom.xml b/extensions/sample/pom.xml
index 8e497de95..78b26cfa7 100644
--- a/extensions/sample/pom.xml
+++ b/extensions/sample/pom.xml
@@ -13,7 +13,7 @@
   <parent>
     <groupId>org.openrefine</groupId>
     <artifactId>extensions</artifactId>
-    <version>3.0-SNAPSHOT</version>
+    <version>3.6-SNAPSHOT</version>
   </parent>
 
   <build>
@@ -25,47 +25,10 @@
     </resources>
     <outputDirectory>module/MOD-INF/classes</outputDirectory>
     <plugins>
-      <plugin>
-        <groupId>org.codehaus.mojo</groupId>
-        <artifactId>build-helper-maven-plugin</artifactId>
-        <version>1.8</version>
-        <executions>
-          <execution>
-            <phase>generate-sources</phase>
-            <goals>
-              <goal>add-source</goal>
-            </goals>
-            <configuration>
-              <sources>
-                <source>src</source>
-              </sources>
-            </configuration>
-          </execution>
-        </executions>
-      </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.1</version>
-        <configuration>
-          <source>${java.minversion}</source>
-          <target>${java.minversion}</target>
-          <encoding>UTF-8</encoding>
-          <showDeprecation>false</showDeprecation>
-        </configuration>
-      </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-resources-plugin</artifactId>
-        <version>2.6</version>
-        <configuration>
-          <encoding>UTF-8</encoding>
-        </configuration>
-      </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-dependency-plugin</artifactId>
-        <version>3.1.1</version>
+	<version>${maven-dependency-plugin.version}</version>
         <executions>
             <execution>
             <phase>compile</phase>
@@ -79,18 +42,6 @@
             </execution>
         </executions>
       </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-clean-plugin</artifactId>
-        <version>3.1.0</version>
-        <configuration>
-          <filesets>
-            <fileset>
-              <directory>module/MOD-INF/lib</directory>
-            </fileset>
-          </filesets>
-        </configuration>
-      </plugin>
     </plugins>
   </build>
 
@@ -103,8 +54,8 @@
     </dependency>
     <dependency>
       <groupId>javax.servlet</groupId>
-      <artifactId>servlet-api</artifactId>
-      <version>2.5</version>
+      <artifactId>javax.servlet-api</artifactId>
+      <version>${servlet-api.version}</version>
       <scope>provided</scope>
     </dependency>
 
@@ -113,7 +64,7 @@
     <dependency>
       <groupId>org.testng</groupId>
       <artifactId>testng</artifactId>
-      <version>6.9.10</version>
+      <version>${testng.version}</version>
       <scope>test</scope>
     </dependency>
   </dependencies>
diff --git a/extensions/wikidata/pom.xml b/extensions/wikidata/pom.xml
index 93ca92521..df6875ed1 100644
--- a/extensions/wikidata/pom.xml
+++ b/extensions/wikidata/pom.xml
@@ -34,43 +34,6 @@
     </testResources>
     <outputDirectory>module/MOD-INF/classes</outputDirectory>
     <plugins>
-      <plugin>
-        <groupId>org.codehaus.mojo</groupId>
-        <artifactId>build-helper-maven-plugin</artifactId>
-        <version>3.2.0</version>
-        <executions>
-          <execution>
-            <phase>generate-sources</phase>
-            <goals>
-              <goal>add-source</goal>
-            </goals>
-            <configuration>
-              <sources>
-                <source>src</source>
-              </sources>
-            </configuration>
-          </execution>
-        </executions>
-      </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.8.1</version>
-        <configuration>
-          <source>${java.minversion}</source>
-          <target>${java.minversion}</target>
-          <encoding>UTF-8</encoding>
-          <showDeprecation>false</showDeprecation>
-        </configuration>
-      </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-resources-plugin</artifactId>
-        <version>3.2.0</version>
-        <configuration>
-          <encoding>UTF-8</encoding>
-        </configuration>
-      </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
@@ -84,7 +47,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-dependency-plugin</artifactId>
-        <version>3.2.0</version>
+	<version>${maven-dependency-plugin.version}</version>
         <executions>
             <execution>
             <phase>compile</phase>
@@ -98,18 +61,6 @@
             </execution>
         </executions>
       </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-clean-plugin</artifactId>
-        <version>3.1.0</version>
-        <configuration>
-          <filesets>
-            <fileset>
-              <directory>module/MOD-INF/lib</directory>
-            </fileset>
-          </filesets>
-        </configuration>
-      </plugin>
     </plugins>
   </build>
 
@@ -122,8 +73,8 @@
     </dependency>
     <dependency>
       <groupId>javax.servlet</groupId>
-      <artifactId>servlet-api</artifactId>
-      <version>2.5</version>
+      <artifactId>javax.servlet-api</artifactId>
+      <version>${servlet-api.version}</version>
       <scope>provided</scope>
     </dependency>
     <dependency>
@@ -149,7 +100,7 @@
     <dependency>
       <groupId>org.slf4j</groupId>
       <artifactId>slf4j-api</artifactId>
-      <version>1.7.32</version>
+      <version>${slf4j.version}</version>
       <scope>provided</scope>
     </dependency>
 
@@ -166,7 +117,7 @@
     <dependency>
       <groupId>org.testng</groupId>
       <artifactId>testng</artifactId>
-      <version>7.4.0</version>
+      <version>${testng.version}</version>
       <scope>test</scope>
     </dependency>
     <dependency>
diff --git a/main/pom.xml b/main/pom.xml
index 67f86f299..82397c79a 100644
--- a/main/pom.xml
+++ b/main/pom.xml
@@ -18,9 +18,6 @@
     <jee.path>/</jee.path>
     <jee.port>3333</jee.port>
     <refine.data>/tmp/refine</refine.data>
-    <powermock.version>2.0.9</powermock.version>
-    <jena.version>4.2.0</jena.version>
-    <poi.version>5.1.0</poi.version>
   </properties>
 
   <scm>
@@ -46,7 +43,7 @@
       <plugin>
         <groupId>org.codehaus.mojo</groupId>
         <artifactId>build-helper-maven-plugin</artifactId>
-        <version>3.2.0</version>
+	<version>${build-helper-maven-plugin.version}</version>
         <executions>
           <execution>
             <phase>generate-sources</phase>
@@ -61,24 +58,6 @@
           </execution>
         </executions>
       </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.8.1</version>
-        <configuration>
-	  <!--release>11</release-->
-          <encoding>UTF-8</encoding>
-          <showDeprecation>false</showDeprecation>
-        </configuration>
-      </plugin>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-resources-plugin</artifactId>
-        <version>3.2.0</version>
-        <configuration>
-          <encoding>UTF-8</encoding>
-        </configuration>
-      </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
@@ -92,7 +71,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-dependency-plugin</artifactId>
-        <version>3.2.0</version>
+	<version>${maven-dependency-plugin.version}</version>
         <executions>
             <execution>
             <phase>compile</phase>
@@ -109,7 +88,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-jar-plugin</artifactId>
-        <version>3.2.0</version>
+	<version>${maven-jar-plugin.version}</version>
         <executions>
           <execution>
             <goals>
@@ -121,7 +100,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-clean-plugin</artifactId>
-        <version>3.1.0</version>
+	<version>${maven-clean-plugin.version}</version>
         <configuration>
           <filesets>
             <fileset>
@@ -133,7 +112,7 @@
     <plugin>
         <groupId>pl.project13.maven</groupId>
         <artifactId>git-commit-id-plugin</artifactId>
-        <version>4.9.10</version>
+	<version>${git-commit-id-plugin.version}</version>
         <executions>
             <execution>
                 <id>get-the-git-infos</id>
@@ -200,52 +179,52 @@
     <dependency>
       <groupId>org.apache.commons</groupId>
       <artifactId>commons-lang3</artifactId>
-      <version>3.12.0</version>
+      <version>${commons-lang3.version}</version>
     </dependency>
     <dependency>
       <groupId>commons-fileupload</groupId>
       <artifactId>commons-fileupload</artifactId>
-      <version>1.4</version>
+      <version>${commons-fileupload.version}</version>
     </dependency>
     <dependency>
       <groupId>commons-collections</groupId>
       <artifactId>commons-collections</artifactId>
-      <version>3.2.2</version>
+      <version>${commons-collections.version}</version>
     </dependency>
     <dependency>
         <groupId>org.apache.commons</groupId>
         <artifactId>commons-text</artifactId>
-        <version>1.9</version>
+	<version>${commons-text.version}</version>
     </dependency>
     <dependency>
       <groupId>commons-validator</groupId>
       <artifactId>commons-validator</artifactId>
-      <version>1.7</version>
+      <version>${commons-validator.version}</version>
     </dependency>
     <dependency>
       <groupId>velocity</groupId>
       <artifactId>velocity</artifactId>
-      <version>1.5</version>
+      <version>${velocity.version}</version>
     </dependency>
     <dependency>
       <groupId>org.marc4j</groupId>
       <artifactId>marc4j</artifactId>
-      <version>2.9.2</version>
+      <version>${marc4j.version}</version>
     </dependency>
     <dependency>
       <groupId>org.apache.commons</groupId>
       <artifactId>commons-compress</artifactId>
-      <version>1.21</version>
+      <version>${commons-compress.version}</version>
     </dependency>
     <dependency>
       <groupId>org.jsoup</groupId>
       <artifactId>jsoup</artifactId>
-      <version>1.14.2</version>
+      <version>${jsoup.version}</version>
     </dependency>
     <dependency>
       <groupId>org.openrefine.dependencies</groupId>
       <artifactId>opencsv-multichar</artifactId>
-      <version>2.4</version>
+      <version>${opencsv-multichar.version}</version>
     </dependency>
     <dependency>
       <groupId>org.apache.poi</groupId>
@@ -260,7 +239,7 @@
     <dependency>
       <groupId>org.odftoolkit</groupId>
       <artifactId>odfdom-java</artifactId>
-      <version>0.10.0</version>
+      <version>${odfdom-java.version}</version>
       <!-- workaround for https://github.com/tdf/odftoolkit/issues/131,
 	 which is unfortunately still not solved after
          https://github.com/tdf/odftoolkit/pull/132
@@ -277,37 +256,37 @@
     <dependency>
       <groupId>org.openrefine.dependencies</groupId>
       <artifactId>vicino</artifactId>
-      <version>1.2</version>
+      <version>${vicino.version}</version>
     </dependency>
     <dependency>
       <groupId>oauth.signpost</groupId>
       <artifactId>signpost-core</artifactId>
-      <version>2.1.1</version>
+      <version>${signpost.version}</version>
     </dependency>
     <dependency>
       <groupId>oauth.signpost</groupId>
       <artifactId>signpost-commonshttp4</artifactId>
-      <version>2.1.1</version>
+      <version>${signpost.version}</version>
     </dependency>
     <dependency>
       <groupId>org.clojure</groupId>
       <artifactId>clojure</artifactId>
-      <version>1.10.3</version>
+      <version>${clojure.version}</version>
     </dependency>
     <dependency>
       <groupId>org.apache.httpcomponents.client5</groupId>
       <artifactId>httpclient5</artifactId>
-      <version>5.1.2</version>
+      <version>${httpclient5.version}</version>
     </dependency>
     <dependency>
       <groupId>org.apache.httpcomponents</groupId>
       <artifactId>httpcore</artifactId>
-      <version>4.4.14</version>
+      <version>${httpcore.version}</version>
     </dependency>
     <dependency>
       <groupId>org.sweble.wikitext</groupId>
       <artifactId>swc-parser-lazy</artifactId>
-      <version>3.1.9</version>
+      <version>${swc-parser-lazy.version}</version>
     </dependency>
 
     <dependency> <!-- reported as unused by dependency:analyze, but tests fail without -->
@@ -320,31 +299,30 @@
       <artifactId>jena-core</artifactId>
       <version>${jena.version}</version>
     </dependency>
-    <!-- v1.15 is needed for Jena 3.14+ - copied from org.apache.jena:jena:pom -->
     <dependency>
       <groupId>commons-codec</groupId>
       <artifactId>commons-codec</artifactId>
-      <version>1.15</version>
+      <version>${commons-codec.version}</version>
     </dependency>
     <dependency>
       <groupId>commons-io</groupId>
       <artifactId>commons-io</artifactId>
-      <version>2.11.0</version>
+      <version>${commons-io.version}</version>
     </dependency>
     <dependency>
       <groupId>com.google.guava</groupId>
       <artifactId>guava</artifactId>
-      <version>31.0.1-jre</version>
+      <version>${guava.version}</version>
     </dependency>
     <dependency>
       <groupId>javax.xml.bind</groupId>
       <artifactId>jaxb-api</artifactId>
-      <version>2.3.1</version>
+      <version>${jaxb-api.version}</version>
     </dependency>
     <dependency>
       <groupId>com.github.albfernandez</groupId>
       <artifactId>juniversalchardet</artifactId>
-      <version>2.4.0</version>
+      <version>${juniversalchardet.version}</version>
     </dependency>
     <dependency> <!-- reported as unused by dependency:analyze, but broken without it -->
       <groupId>org.eclipse.jetty</groupId>
@@ -357,7 +335,7 @@
     <dependency>
       <groupId>org.testng</groupId>
       <artifactId>testng</artifactId>
-      <version>7.4.0</version>
+      <version>${testng.version}</version>
       <scope>test</scope>
     </dependency>
     <dependency>
@@ -381,7 +359,7 @@
     <dependency>
       <groupId>org.apache.httpcomponents</groupId>
       <artifactId>httpmime</artifactId>
-      <version>4.5.13</version>
+      <version>${httpmime.version}</version>
       <scope>test</scope>
     </dependency>
   </dependencies>
diff --git a/pom.xml b/pom.xml
index 12c737851..7d3cf9ed4 100644
--- a/pom.xml
+++ b/pom.xml
@@ -59,15 +59,61 @@
     <jee.path>/</jee.path>
     <jee.port>3333</jee.port>
     <refine.data>/tmp/refine</refine.data>
-    <surefire.version>2.22.2</surefire.version>
     <surefireArgs/>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+
+    <!-- dependency versions -->
     <jackson.version>2.13.0</jackson.version>
     <servlet-api.version>4.0.1</servlet-api.version>
     <butterfly.version>1.2.0</butterfly.version>
     <slf4j.version>1.7.32</slf4j.version>
     <jetty.version>9.4.41.v20210516</jetty.version>
     <okhttp.version>4.9.3</okhttp.version>
+    <jena.version>4.2.0</jena.version>
+    <poi.version>5.1.0</poi.version>
+    <powermock.version>2.0.9</powermock.version>
+    <commons-lang3.version>3.12.0</commons-lang3.version>
+    <commons-fileupload.version>1.4</commons-fileupload.version>
+    <commons-collections.version>3.2.2</commons-collections.version>
+    <commons-text.version>1.9</commons-text.version>
+    <commons-validator.version>1.7</commons-validator.version>
+    <!-- v1.15 of commons-codec is needed for Jena 3.14+ - copied from org.apache.jena:jena:pom -->
+    <commons-codec.version>1.15</commons-codec.version>
+    <commons-compress.version>1.21</commons-compress.version>
+    <velocity.version>1.5</velocity.version>
+    <marc4j.version>2.9.2</marc4j.version>
+    <jsoup.version>1.14.2</jsoup.version>
+    <odfdom-java.version>0.10.0</odfdom-java.version>
+    <vicino.version>1.2</vicino.version>
+    <signpost.version>2.1.1</signpost.version>
+    <clojure.version>1.10.3</clojure.version>
+    <httpclient.version>4.5.13</httpclient.version>
+    <httpclient5.version>5.1.2</httpclient5.version>
+    <httpcore.version>4.4.14</httpcore.version>
+    <opencsv-multichar.version>2.4</opencsv-multichar.version>
+    <swc-parser-lazy.version>3.1.9</swc-parser-lazy.version>
+    <commons-io.version>2.11.0</commons-io.version>
+    <guava.version>31.0.1-jre</guava.version>
+    <jaxb-api.version>2.3.1</jaxb-api.version>
+    <juniversalchardet.version>2.4.0</juniversalchardet.version>
+    <testng.version>7.4.0</testng.version>
+    <httpmime.version>4.5.13</httpmime.version>
+    <owasp-encoder.version>1.2.3</owasp-encoder.version>
+    <jasypt.version>1.9.3</jasypt.version>
+    <mockito.version>4.1.0</mockito.version>
+
+    <!-- plugin versions -->
+    <build-helper-maven-plugin.version>3.2.0</build-helper-maven-plugin.version>
+    <maven-compiler-plugin.version>3.8.1</maven-compiler-plugin.version>
+    <maven-resources-plugin.version>3.2.0</maven-resources-plugin.version>
+    <exec-maven-plugin.version>3.0.0</exec-maven-plugin.version>
+    <maven-dependency-plugin.version>3.2.0</maven-dependency-plugin.version>
+    <jacoco-maven-plugin.version>0.8.7</jacoco-maven-plugin.version>
+    <coveralls-maven-plugin.version>4.3.0</coveralls-maven-plugin.version>
+    <surefire.version>2.22.2</surefire.version>
+    <maven-jar-plugin.version>3.2.0</maven-jar-plugin.version>
+    <maven-clean-plugin.version>3.1.0</maven-clean-plugin.version>
+    <git-commit-id-plugin.version>4.9.10</git-commit-id-plugin.version>
   </properties>
 
 
@@ -82,7 +128,7 @@
       <plugin>
         <groupId>org.codehaus.mojo</groupId>
         <artifactId>build-helper-maven-plugin</artifactId>
-        <version>3.2.0</version>
+	<version>${build-helper-maven-plugin.version}</version>
         <executions>
           <execution>
             <phase>generate-sources</phase>
@@ -100,7 +146,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.8.1</version>
+	<version>${maven-compiler-plugin.version}</version>
         <configuration>
           <source>${java.minversion}</source>
           <target>${java.minversion}</target>
@@ -111,7 +157,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-resources-plugin</artifactId>
-        <version>3.2.0</version>
+	<version>${maven-resources-plugin.version}</version>
         <configuration>
           <encoding>UTF-8</encoding>
         </configuration>
@@ -119,7 +165,7 @@
       <plugin>
         <groupId>org.codehaus.mojo</groupId>
         <artifactId>exec-maven-plugin</artifactId>
-        <version>3.0.0</version>
+	<version>${exec-maven-plugin.version}</version>
         <configuration>
           <skip>true</skip>
           <mainClass>none</mainClass>
@@ -128,7 +174,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-dependency-plugin</artifactId>
-        <version>3.2.0</version>
+	<version>${maven-dependency-plugin.version}</version>
       </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
@@ -144,7 +190,7 @@
       <plugin>
         <groupId>org.jacoco</groupId>
         <artifactId>jacoco-maven-plugin</artifactId>
-        <version>0.8.7</version>
+	<version>${jacoco-maven-plugin.version}</version>
         <executions>
             <execution>
                 <id>prepare-agent</id>
@@ -196,7 +242,7 @@
       <plugin>
         <groupId>org.eluder.coveralls</groupId>
         <artifactId>coveralls-maven-plugin</artifactId>
-        <version>4.3.0</version>
+	<version>${coveralls-maven-plugin.version}</version>
         <dependencies>
           <dependency>
             <groupId>javax.xml.bind</groupId>
diff --git a/server/pom.xml b/server/pom.xml
index b62649a54..841a9215b 100644
--- a/server/pom.xml
+++ b/server/pom.xml
@@ -37,7 +37,7 @@
       <plugin>
         <groupId>org.codehaus.mojo</groupId>
         <artifactId>build-helper-maven-plugin</artifactId>
-        <version>3.2.0</version>
+	<version>${build-helper-maven-plugin.version}</version>
         <executions>
           <execution>
             <phase>generate-sources</phase>
@@ -55,7 +55,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.8.1</version>
+	<version>${maven-compiler-plugin.version}</version>
         <configuration>
           <source>${java.minversion}</source>
           <target>${java.minversion}</target>
@@ -66,7 +66,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-resources-plugin</artifactId>
-        <version>3.2.0</version>
+	<version>${maven-resources-plugin.version}</version>
         <configuration>
           <encoding>UTF-8</encoding>
         </configuration>
@@ -74,7 +74,7 @@
       <plugin>
         <groupId>org.codehaus.mojo</groupId>
         <artifactId>exec-maven-plugin</artifactId>
-        <version>3.0.0</version>
+	<version>${exec-maven-plugin.version}</version>
         <configuration>
           <mainClass>com.google.refine.Refine</mainClass>
           <commandlineArgs>-Drefine.headless=true -Drefine.autoreload=true -Dbutterfly.autoreload=true -Drefine.memory=1400M -Drefine.port=3333 -Drefine.host=127.0.0.1</commandlineArgs>
@@ -84,7 +84,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
-        <version>2.22.0</version>
+	<version>${surefire.version}</version>
         <configuration>
           <skip>true</skip>
         </configuration>
@@ -95,7 +95,7 @@
         <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-dependency-plugin</artifactId>
-            <version>3.2.0</version>
+	    <version>${maven-dendency-plugin.version}</version>
             <configuration>
                 <includeScope>runtime</includeScope>
             </configuration>