diff --git a/README.md b/README.md
index a617b91..3466a70 100644
--- a/README.md
+++ b/README.md
@@ -84,6 +84,7 @@ gamja settings can be overridden using URL query parameters:
 - `nick`: nickname
 - `channels`: comma-separated list of channels to join (`#` needs to be escaped)
 - `open`: [IRC URL] to open
+- `debug`: if set to 1, debug mode is enabled
 
 Alternatively, the channels can be set with the URL fragment (ie, by just
 appending the channel name to the gamja URL).
diff --git a/components/app.js b/components/app.js
index fd16f6c..9d665e5 100644
--- a/components/app.js
+++ b/components/app.js
@@ -48,6 +48,15 @@ const configPromise = fetch("./config.json")
 
 const CHATHISTORY_MAX_SIZE = 4000;
 
+function isProduction() {
+	// NODE_ENV is set by the Parcel build system
+	try {
+		return process.env.NODE_ENV === "production";
+	} catch (err) {
+		return false;
+	}
+}
+
 function parseQueryString() {
 	let query = window.location.search.substring(1);
 	let params = {};
@@ -162,6 +171,7 @@ export default class App extends Component {
 			memberList: false,
 		},
 	};
+	debug = !isProduction();
 	config = { ...baseConfig };
 	clients = new Map();
 	endOfHistory = new Map();
@@ -279,6 +289,9 @@ export default class App extends Component {
 		if (typeof queryParams.open === "string") {
 			this.autoOpenURL = irc.parseURL(queryParams.open);
 		}
+		if (queryParams.debug === "1") {
+			this.debug = true;
+		}
 
 		if (window.location.hash) {
 			autojoin = window.location.hash.split(",");
@@ -579,6 +592,8 @@ export default class App extends Component {
 		this.setState({ connectParams: params });
 
 		let client = new Client(fillConnectParams(params));
+		client.debug = this.debug;
+
 		this.clients.set(serverID, client);
 		this.setServerState(serverID, { status: client.status });
 
diff --git a/lib/client.js b/lib/client.js
index c4f1beb..5b471a5 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -76,6 +76,7 @@ export default class Client extends EventTarget {
 		saslExternal: false,
 		bouncerNetwork: null,
 	};
+	debug = false;
 	batches = new Map();
 	autoReconnect = true;
 	reconnectTimeoutID = null;
@@ -225,7 +226,9 @@ export default class Client extends EventTarget {
 		}
 
 		let msg = irc.parseMessage(event.data);
-		console.debug("Received:", msg);
+		if (this.debug) {
+			console.debug("Received:", msg);
+		}
 
 		// If the prefix is missing, assume it's coming from the server on the
 		// other end of the connection
@@ -653,7 +656,9 @@ export default class Client extends EventTarget {
 			throw new Error("Failed to send IRC message " + msg.command + ": socket is closed");
 		}
 		this.ws.send(irc.formatMessage(msg));
-		console.debug("Sent:", msg);
+		if (this.debug) {
+			console.debug("Sent:", msg);
+		}
 	}
 
 	setCaseMapping(name) {