diff --git a/docs/docker.rst b/docs/docker.rst
index b628749..d277867 100644
--- a/docs/docker.rst
+++ b/docs/docker.rst
@@ -1,75 +1,78 @@
 Graph Docker environment
 ========================
 
 
 Build
 -----
 
 .. code:: bash
 
     $ git clone https://forge.softwareheritage.org/source/swh-graph.git
     $ cd swh-graph
     $ docker build --tag swh-graph dockerfiles
 
 
 Run
 ---
 
 Given a graph ``g`` specified by:
 
 - ``g.edges.csv.gz``: gzip-compressed csv file with one edge per line, as a
   "SRC_ID SPACE DST_ID" string, where identifiers are the
   :ref:`persistent-identifiers` of each node.
 - ``g.nodes.csv.gz``: sorted list of unique node identifiers appearing in the
   corresponding ``g.edges.csv.gz`` file. The format is a gzip-compressed csv
   file with one persistent identifier per line.
 
 .. code:: bash
 
     $ docker run -ti \
         --volume /PATH/TO/GRAPH/:/srv/softwareheritage/graph/data \
         --publish 127.0.0.1:5009:5009 \
         swh-graph:latest \
 	bash
 
 Where ``/PATH/TO/GRAPH`` is a directory containing the ``g.edges.csv.gz`` and
 ``g.nodes.csv.gz`` files.  By default, when entering the container the current
 working directory will be ``/srv/softwareheritage/graph``; all relative paths
 found below are intended to be relative to that dir.
 
 
 Graph compression
 ~~~~~~~~~~~~~~~~~
 
 To compress the graph:
 
 .. code:: bash
 
     $ app/scripts/compress_graph.sh --lib lib/ --input data/g
 
 Warning: very large graphs may need a bigger batch size parameter for WebGraph
 internals (you can specify a value when running the compression script using:
 ``--batch-size 1000000000``).
 
 
 Node identifier mappings
 ~~~~~~~~~~~~~~~~~~~~~~~~
 
 To dump the mapping files (i.e., various node id <-> other info mapping files,
 in either ``.csv.gz`` or ad-hoc ``.map`` format):
 
 .. code:: bash
 
     $ java -cp app/swh-graph.jar \
         org.softwareheritage.graph.backend.Setup data/compressed/g
 
 
 Graph server
 ~~~~~~~~~~~~
 
 To start the swh-graph server:
 
 .. code:: bash
 
     $ java -cp app/swh-graph.jar \
         org.softwareheritage.graph.App data/compressed/g
+
+To specify the port on which the server will run, use the `--port` or `-p` flag
+(default is 5009).
diff --git a/java/server/pom.xml b/java/server/pom.xml
index 5cd22a0..544be2f 100644
--- a/java/server/pom.xml
+++ b/java/server/pom.xml
@@ -1,146 +1,151 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
 
     <groupId>org.softwareheritage.graph</groupId>
     <artifactId>swh-graph</artifactId>
     <version>1.0</version>
 
     <name>swh-graph</name>
     <url>https://www.softwareheritage.org/</url>
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <maven.compiler.release>11</maven.compiler.release>
     </properties>
 
     <dependencies>
         <dependency>
             <groupId>ch.qos.logback</groupId>
             <artifactId>logback-classic</artifactId>
             <version>1.2.3</version>
         </dependency>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
             <version>4.11</version>
             <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.hamcrest</groupId>
             <artifactId>hamcrest</artifactId>
             <version>2.1</version>
             <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>io.javalin</groupId>
             <artifactId>javalin</artifactId>
             <version>3.0.0</version>
         </dependency>
         <dependency>
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-simple</artifactId>
             <version>1.7.26</version>
         </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>
             <version>2.9.8</version>
         </dependency>
         <dependency>
             <groupId>it.unimi.dsi</groupId>
             <artifactId>webgraph-big</artifactId>
             <version>3.5.1</version>
         </dependency>
         <dependency>
             <groupId>it.unimi.dsi</groupId>
             <artifactId>fastutil</artifactId>
             <version>8.2.2</version>
         </dependency>
+        <dependency>
+            <groupId>com.martiansoftware</groupId>
+            <artifactId>jsap</artifactId>
+            <version>2.1</version>
+        </dependency>
     </dependencies>
 
     <build>
         <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
             <plugins>
                 <!-- clean lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#clean_Lifecycle -->
                 <plugin>
                     <artifactId>maven-clean-plugin</artifactId>
                     <version>3.1.0</version>
                 </plugin>
                 <!-- default lifecycle, jar packaging: see https://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
                 <plugin>
                     <artifactId>maven-resources-plugin</artifactId>
                     <version>3.0.2</version>
                 </plugin>
                 <plugin>
                     <artifactId>maven-compiler-plugin</artifactId>
                     <version>3.8.0</version>
                     <configuration>
                         <compilerArgs>
                             <arg>-verbose</arg>
                             <arg>-Xlint:all</arg>
                         </compilerArgs>
                     </configuration>
                 </plugin>
                 <plugin>
                     <artifactId>maven-surefire-plugin</artifactId>
                     <version>2.22.1</version>
                 </plugin>
                 <plugin>
                     <artifactId>maven-jar-plugin</artifactId>
                     <version>3.0.2</version>
                 </plugin>
                 <plugin>
                     <artifactId>maven-install-plugin</artifactId>
                     <version>2.5.2</version>
                 </plugin>
                 <plugin>
                     <artifactId>maven-deploy-plugin</artifactId>
                     <version>2.8.2</version>
                 </plugin>
                 <!-- site lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#site_Lifecycle -->
                 <plugin>
                     <artifactId>maven-site-plugin</artifactId>
                     <version>3.7.1</version>
                 </plugin>
                 <plugin>
                     <artifactId>maven-project-info-reports-plugin</artifactId>
                     <version>3.0.0</version>
                 </plugin>
                 <plugin>
                     <artifactId>maven-assembly-plugin</artifactId>
                     <configuration>
                         <archive>
                             <manifest>
                                 <mainClass>org.softwareheritage.graph.App</mainClass>
                             </manifest>
                         </archive>
                         <descriptorRefs>
                             <descriptorRef>jar-with-dependencies</descriptorRef>
                         </descriptorRefs>
                     </configuration>
                     <executions>
                         <execution>
                             <id>make-assembly</id> <!-- this is used for inheritance merges -->
                             <phase>package</phase> <!-- bind to the packaging phase -->
                             <goals>
                                 <goal>single</goal>
                             </goals>
                         </execution>
                     </executions>
                 </plugin>
             </plugins>
         </pluginManagement>
     </build>
     <reporting>
         <plugins>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-javadoc-plugin</artifactId>
                 <version>3.1.1</version>
             </plugin>
         </plugins>
     </reporting>
 </project>
diff --git a/java/server/src/main/java/org/softwareheritage/graph/App.java b/java/server/src/main/java/org/softwareheritage/graph/App.java
index af56ca8..654597c 100644
--- a/java/server/src/main/java/org/softwareheritage/graph/App.java
+++ b/java/server/src/main/java/org/softwareheritage/graph/App.java
@@ -1,122 +1,151 @@
 package org.softwareheritage.graph;
 
 import java.io.IOException;
 import java.util.List;
 import java.util.Map;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.PropertyNamingStrategy;
+import com.martiansoftware.jsap.FlaggedOption;
+import com.martiansoftware.jsap.JSAP;
+import com.martiansoftware.jsap.JSAPException;
+import com.martiansoftware.jsap.JSAPResult;
+import com.martiansoftware.jsap.Parameter;
+import com.martiansoftware.jsap.SimpleJSAP;
+import com.martiansoftware.jsap.UnflaggedOption;
 import io.javalin.Javalin;
 import io.javalin.http.Context;
 import io.javalin.plugin.json.JavalinJackson;
 
 import org.softwareheritage.graph.Endpoint;
 import org.softwareheritage.graph.Graph;
 import org.softwareheritage.graph.SwhId;
 import org.softwareheritage.graph.algo.Stats;
 
 /**
  * Entrypoint of the swh-graph server REST API.
  *
  * @author Thibault Allançon
  * @version 1.0
  * @since 1.0
  */
 
 public class App {
-  public static void main(String[] args) throws IOException {
-    String path = args[0];
-    Graph graph = new Graph(path);
-    Stats stats = new Stats(path);
+  public static void main(String[] args) throws IOException, JSAPException {
+    SimpleJSAP jsap = new SimpleJSAP(
+        App.class.getName(),
+        "Server to load and query a compressed graph representation of Software Heritage archive.",
+        new Parameter[] {
+          new FlaggedOption("port", JSAP.INTEGER_PARSER, "5009", JSAP.NOT_REQUIRED, 'p', "port",
+              "Binding port of the server."),
+          new UnflaggedOption("graphPath", JSAP.STRING_PARSER, JSAP.NO_DEFAULT, JSAP.REQUIRED,
+              JSAP.NOT_GREEDY, "The basename of the compressed graph."),
+        }
+    );
+
+    JSAPResult config = jsap.parse(args);
+    if (jsap.messagePrinted()) {
+      System.exit(1);
+    }
+
+    String graphPath = config.getString("graphPath");
+    int port = config.getInt("port");
+
+    startServer(graphPath, port);
+  }
+
+  private static void startServer(String graphPath, int port) throws IOException {
+    Graph graph = new Graph(graphPath);
+    Stats stats = new Stats(graphPath);
 
     // Clean up on exit
     Runtime.getRuntime().addShutdownHook(new Thread() {
       public void run() {
         try {
           graph.cleanUp();
         } catch (IOException e) {
           System.out.println("Could not clean up graph on exit: " + e);
         }
       }
     });
 
     // Configure Jackson JSON to use snake case naming style
     ObjectMapper objectMapper = JavalinJackson.getObjectMapper();
     objectMapper.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);
     JavalinJackson.configure(objectMapper);
 
-    Javalin app = Javalin.create().start(5009);
+    Javalin app = Javalin.create().start(port);
 
     app.before("/stats/*", ctx -> { checkQueryStrings(ctx, ""); });
     app.before("/leaves/*", ctx -> { checkQueryStrings(ctx, "direction|edges"); });
     app.before("/neighbors/*", ctx -> { checkQueryStrings(ctx, "direction|edges"); });
     app.before("/visit/*", ctx -> { checkQueryStrings(ctx, "direction|edges"); });
     app.before("/walk/*", ctx -> { checkQueryStrings(ctx, "direction|edges|traversal"); });
 
     app.get("/stats/", ctx -> { ctx.json(stats); });
 
     // Graph traversal endpoints
     // By default the traversal is a forward DFS using all edges
 
     app.get("/leaves/:src", ctx -> {
       SwhId src = new SwhId(ctx.pathParam("src"));
       String direction = ctx.queryParam("direction", "forward");
       String edgesFmt = ctx.queryParam("edges", "*");
 
       Endpoint endpoint = new Endpoint(graph, direction, edgesFmt);
       ctx.json(endpoint.leaves(src));
     });
 
     app.get("/neighbors/:src", ctx -> {
       SwhId src = new SwhId(ctx.pathParam("src"));
       String direction = ctx.queryParam("direction", "forward");
       String edgesFmt = ctx.queryParam("edges", "*");
 
       Endpoint endpoint = new Endpoint(graph, direction, edgesFmt);
       ctx.json(endpoint.neighbors(src));
     });
 
     app.get("/visit/nodes/:src", ctx -> {
       SwhId src = new SwhId(ctx.pathParam("src"));
       String direction = ctx.queryParam("direction", "forward");
       String edgesFmt = ctx.queryParam("edges", "*");
 
       Endpoint endpoint = new Endpoint(graph, direction, edgesFmt);
       ctx.json(endpoint.visitNodes(src));
     });
 
     app.get("/visit/paths/:src", ctx -> {
       SwhId src = new SwhId(ctx.pathParam("src"));
       String direction = ctx.queryParam("direction", "forward");
       String edgesFmt = ctx.queryParam("edges", "*");
 
       Endpoint endpoint = new Endpoint(graph, direction, edgesFmt);
       ctx.json(endpoint.visitPaths(src));
     });
 
     app.get("/walk/:src/:dst", ctx -> {
       SwhId src = new SwhId(ctx.pathParam("src"));
       String dstFmt = ctx.pathParam("dst");
       String direction = ctx.queryParam("direction", "forward");
       String edgesFmt = ctx.queryParam("edges", "*");
       String algorithm = ctx.queryParam("traversal", "dfs");
 
       Endpoint endpoint = new Endpoint(graph, direction, edgesFmt);
       ctx.json(endpoint.walk(src, dstFmt, algorithm));
     });
 
     app.exception(IllegalArgumentException.class, (e, ctx) -> {
       ctx.status(400);
       ctx.result(e.getMessage());
     });
   }
 
   private static void checkQueryStrings(Context ctx, String allowedFmt) {
     Map<String, List<String>> queryParamMap = ctx.queryParamMap();
     for (String key : queryParamMap.keySet()) {
       if (!key.matches(allowedFmt)) {
         throw new IllegalArgumentException("Unknown query string: " + key);
       }
     }
   }
 }