diff --git a/package.json b/package.json
index d180f1563..da9a4be28 100644
--- a/package.json
+++ b/package.json
@@ -72,6 +72,7 @@
     "@types/eslint-plugin-prettier": "^2.2.0",
     "@types/express": "^4.16.1",
     "@types/express-jwt": "^0.0.42",
+    "@types/get-port": "^4.2.0",
     "@types/glob": "^7.1.1",
     "@types/graphql": "^14.2.0",
     "@types/history": "^4.7.2",
@@ -131,6 +132,7 @@
     "eslint-plugin-react": "^7.12.4",
     "file-loader": "^3.0.1",
     "front-matter": "^3.0.1",
+    "get-port": "^4.2.0",
     "glob": "^7.1.3",
     "husky": "^1.3.1",
     "identity-obj-proxy": "^3.0.0",
diff --git a/tools/codegen.ts b/tools/codegen.ts
index 5fec2c22e..5b63f9894 100644
--- a/tools/codegen.ts
+++ b/tools/codegen.ts
@@ -1,4 +1,5 @@
 import { ApolloServer } from 'apollo-server';
+import getPort from 'get-port';
 import { spawn } from './lib/cp';
 import webpackConfig from './webpack.config';
 import runWebpack from './lib/runWebpack';
@@ -26,15 +27,17 @@ export default async function codegen() {
     serverConfig.stats,
   );
 
+  const port = await getPort();
+
   // eslint-disable-next-line global-require, import/no-dynamic-require, import/no-unresolved
   const builtSchema = require('../build/schema').default;
   const server = new ApolloServer(builtSchema);
-  const { server: httpServer } = await server.listen({ port: 3900 });
+  const { server: httpServer } = await server.listen({ port });
 
   await spawn('yarn', [
     'apollo', 'client:codegen',
     '--target', 'typescript',
-    '--endpoint', 'http://localhost:3900/graphql',
+    '--endpoint', `http://localhost:${port}/graphql`,
   ], {
     stdio: 'inherit',
   });
diff --git a/yarn.lock b/yarn.lock
index f2f8b6bc3..a9bb26cad 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1624,6 +1624,13 @@
   dependencies:
     "@types/node" "*"
 
+"@types/get-port@^4.2.0":
+  version "4.2.0"
+  resolved "https://registry.yarnpkg.com/@types/get-port/-/get-port-4.2.0.tgz#4fc44616c737d37d3ee7926d86fa975d0afba5e4"
+  integrity sha512-Iv2FAb5RnIk/eFO2CTu8k+0VMmIR15pKbcqRWi+s3ydW+aKXlN2yemP92SrO++ERyJx+p6Ie1ggbLBMbU1SjiQ==
+  dependencies:
+    get-port "*"
+
 "@types/glob@*", "@types/glob@^7.1.1":
   version "7.1.1"
   resolved "https://registry.yarnpkg.com/@types/glob/-/glob-7.1.1.tgz#aa59a1c6e3fbc421e07ccd31a944c30eba521575"
@@ -6368,6 +6375,11 @@ get-own-enumerable-property-symbols@^2.0.1:
   version "2.0.1"
   resolved "https://registry.yarnpkg.com/get-own-enumerable-property-symbols/-/get-own-enumerable-property-symbols-2.0.1.tgz#5c4ad87f2834c4b9b4e84549dc1e0650fb38c24b"
 
+get-port@*, get-port@^4.2.0:
+  version "4.2.0"
+  resolved "https://registry.yarnpkg.com/get-port/-/get-port-4.2.0.tgz#e37368b1e863b7629c43c5a323625f95cf24b119"
+  integrity sha512-/b3jarXkH8KJoOMQc3uVGHASwGLPq3gSFJ7tgJm2diza+bydJPTGOibin2steecKeOylE8oY2JERlVWkAJO6yw==
+
 get-stdin@^4.0.1:
   version "4.0.1"
   resolved "https://registry.yarnpkg.com/get-stdin/-/get-stdin-4.0.1.tgz#b968c6b0a04384324902e8bf1a5df32579a450fe"