diff --git a/src/api.ts b/src/api.ts
index 7b9bf44..706c522 100644
--- a/src/api.ts
+++ b/src/api.ts
@@ -6,6 +6,7 @@ import {
 	getPoolsWithUser,
 	getUserByID,
 } from './data';
+import { PoolModel } from './models';
 
 export const router = Router();
 
@@ -114,6 +115,21 @@ router.get('/group', (req, res) => {
 	}
 });
 
+router.post('/join_pool', async (req, res) => {
+	if (!req.session.accountID) {
+		return res.json({ status: 'error', error: 'need_login' });
+	} else {
+		let poolID = req.body.id;
+		let userID = req.session.accountID;
+
+		await PoolModel.findByIdAndUpdate(poolID, {
+			$addToSet: { participant_ids: userID },
+		}).exec();
+
+		res.json({ status: 'success' });
+	}
+});
+
 router.post('/group', (req, res) => {
 	// if (req.body.groupID in groups) {
 	// 	res.json({ status: 'error', error: 'already_exists' });