@app.route('/')
def index():
    ......

@app.route('app1')
def app1():
    ......
    return render_template('app1.html')

@app.route('app2')
def app1():
    ......
    return render_template('app2.html')

......

app = Flask(__name__)

if __name__ == "__main__":
    app.run()

app = Flask(__name__)
app.config['SECRET_KEY'] = 'secret!'
socketio = SocketIO(app)

if __name__ == '__main__':
    socketio.run(app)