diff --git a/src/main/java/com/conveyal/datatools/manager/models/Deployment.java b/src/main/java/com/conveyal/datatools/manager/models/Deployment.java
index 04731841a..cb06e25fd 100644
--- a/src/main/java/com/conveyal/datatools/manager/models/Deployment.java
+++ b/src/main/java/com/conveyal/datatools/manager/models/Deployment.java
@@ -49,6 +49,7 @@
 import java.util.zip.ZipOutputStream;
 
 import static com.conveyal.datatools.manager.DataManager.getConfigPropertyAsText;
+import static com.conveyal.datatools.manager.utils.HttpUtils.downloadFileFromURL;
 import static com.mongodb.client.model.Filters.and;
 import static com.mongodb.client.model.Filters.eq;
 
@@ -209,7 +210,9 @@ public DeployJob.DeploySummary latest () {
     public String routerId;
 
     public String customBuildConfig;
+    public String customBuildConfigUrl;
     public String customRouterConfig;
+    public String customRouterConfigUrl;
 
     public List<CustomFile> customFiles = new ArrayList<>();
 
@@ -414,14 +417,42 @@ public void dump (File output, boolean includeManifest, boolean includeOsm, bool
         out.close();
     }
 
-    /** Generate build config for deployment as byte array (for writing to file output stream). */
-    public byte[] generateBuildConfig() {
-        Project project = this.parentProject();
+    /** Download config from provided URL. */
+    public String downloadConfig(String configUrl) throws IOException {
+        if (configUrl != null) {
+            try {
+                // TODO: validate JSON?
+                return new String(downloadFileFromURL(new URL(configUrl)), StandardCharsets.UTF_8);
+            } catch (IOException e) {
+                String message = String.format("Could not download config file from %s.", configUrl);
+                LOG.error(message);
+                throw new IOException(message, e);
+            }
+        }
+        return null;
+    }
+
+    /** Generate build config for deployment as byte array (for writing to file output stream). If an external build
+     * config is available and is successfully downloaded, use this instead of the deployment build config. If there is
+     * no deployment build config, use the project build config. */
+    public byte[] generateBuildConfig() throws IOException {
+        String downloadedConfig = downloadConfig(customBuildConfigUrl);
+        if (downloadedConfig != null) {
+            customBuildConfig = downloadedConfig;
+        }
         return customBuildConfig != null
             ? customBuildConfig.getBytes(StandardCharsets.UTF_8)
-            : project.buildConfig != null
-                ? writeToBytes(project.buildConfig)
-                : null;
+            : getProjectBuildConfig();
+    }
+
+    /**
+     * If a project build config exists, return this as a byte array, or null if not available.
+     */
+    private byte[] getProjectBuildConfig() {
+        Project project = parentProject();
+        return project.buildConfig != null
+            ? writeToBytes(project.buildConfig)
+            : null;
     }
 
     public String generateBuildConfigAsString() {
@@ -451,15 +482,18 @@ private <O extends Serializable> String writeToString(O object) {
 
     /** Generate router config for deployment as string. */
     public byte[] generateRouterConfig() throws IOException {
-        Project project = this.parentProject();
+        String downloadedConfig = downloadConfig(customRouterConfigUrl);
+        if (downloadedConfig != null) {
+            customRouterConfig = downloadedConfig;
+        }
 
         byte[] customRouterConfigString = customRouterConfig != null
-                ? customRouterConfig.getBytes(StandardCharsets.UTF_8)
-                : null;
+            ? customRouterConfig.getBytes(StandardCharsets.UTF_8)
+            : null;
 
-        byte[] routerConfigString = project.routerConfig != null
-                ? writeToBytes(project.routerConfig)
-                : null;
+        byte[] routerConfigString = parentProject().routerConfig != null
+            ? writeToBytes(parentProject().routerConfig)
+            : null;
 
         // If both router configs are present, merge the JSON before returning
         // Merger code from: https://stackoverflow.com/questions/35747813/how-to-merge-two-json-strings-into-one-in-java
diff --git a/src/main/java/com/conveyal/datatools/manager/utils/HttpUtils.java b/src/main/java/com/conveyal/datatools/manager/utils/HttpUtils.java
index fdd6ed0d5..2f3461a9a 100644
--- a/src/main/java/com/conveyal/datatools/manager/utils/HttpUtils.java
+++ b/src/main/java/com/conveyal/datatools/manager/utils/HttpUtils.java
@@ -14,9 +14,12 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.io.ByteArrayOutputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.UnsupportedEncodingException;
 import java.net.URI;
+import java.net.URL;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -113,4 +116,21 @@ public static SimpleHttpResponse httpRequestRawResponse(
             return null;
         }
     }
+
+    /**
+     * Download a file from a URL and return as a byte array.
+     */
+    public static byte[] downloadFileFromURL(URL url) throws IOException {
+        try (
+            InputStream inputStream = url.openStream();
+            ByteArrayOutputStream outputStream = new ByteArrayOutputStream()
+        ) {
+            byte[] chunk = new byte[4096];
+            int bytesRead;
+            while ((bytesRead = inputStream.read(chunk)) >= 0) {
+                outputStream.write(chunk, 0, bytesRead);
+            }
+            return outputStream.toByteArray();
+        }
+    }
 }
diff --git a/src/test/java/com/conveyal/datatools/manager/jobs/DeployJobTest.java b/src/test/java/com/conveyal/datatools/manager/jobs/DeployJobTest.java
index d3812276a..e0504d589 100644
--- a/src/test/java/com/conveyal/datatools/manager/jobs/DeployJobTest.java
+++ b/src/test/java/com/conveyal/datatools/manager/jobs/DeployJobTest.java
@@ -27,6 +27,7 @@
 import static com.zenika.snapshotmatcher.SnapshotMatcher.matchesSnapshot;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assumptions.assumeTrue;
 
 /**
@@ -80,6 +81,15 @@ public static void setUp() throws IOException {
         Persistence.deployments.create(deployment);
     }
 
+    @Test
+    void canDownloadConfigs() throws IOException {
+        deployment.customBuildConfigUrl = "http://www.google.com";
+        assertNotNull(deployment.downloadConfig(deployment.customBuildConfigUrl));
+
+        deployment.customRouterConfigUrl = "http://www.google.com";
+        assertNotNull(deployment.downloadConfig(deployment.customRouterConfigUrl));
+    }
+
     /**
      * Tests that the otp-runner manifest and user data for a graph build + run server instance can be generated
      * properly