router.post("accounts/transactions", async (req, res) => { //user id sent from frontend const user_id = req.body.user_id; //Find accounts by user_id in DB const accounts = Account.find({ user_id: user_id }).then((accounts) => { return accounts; }); //Once accounts retrieved from DB, loop over them and fetch transactions for each account (await accounts).forEach(async (account) => { const url = `https://someExternalApi.whatever/${account.accountId}/transactions`; const options = { //fetch request options }; const response = await fetch(url, options) .then((res) => res.json()) .catch((e) => { console.error({ message: "Error!", error: e, }); }); //Once transactions for a single account are retrieved from external API, //loop over them and save them one-by-one to DB (await response).transactions.booked.forEach(async (transaction) => { const filter = { transactionId: transaction.transactionId }; const mongooseOptions = { upsert: true, new: true }; const update = { user_id: user_id, //...other keys-value pairs for transaction record updated: Date.now(), }; //Save single transaction to DB Transaction.findOneAndUpdate(filter, update, mongooseOptions) .then( console.log( `Transaction ${ transaction.transactionId } saved!` ) ) .catch((error) => console.log(error)); }); }); //The problem is that the below runs before the above async operations are finished console.log("All transactions updated!"); Transaction.find({ user_id: user_id }).then((transactions) => { res.json(transactions); }); });