This is an urgent situation. Please try to stay calm and focus on the facts. Emotions and allegations won't help fixing the issue.
Most downtime we see is caused by "client coding mistakes" - usually by not making proper use of the available resources. In many cases we can help you to solve the issue.
Many of such errors can be resolved by analyzing logs files and metrics. We are happy to discuss and research such problems together with our clients.
By providing enough details you may can help us spot a service issue faster.
Make sure to provide the exact App name. Is the happening to just one App hosted here or to multiple or all?
When you are the Owner of the App but not the technical contact we advice to get your developer in contact with us.
Did you maybe recently pushed code? Or did some editor changed some setting on the App? Or was there any other change done, prior the downtime? Maybe someone uploaded a lot of images or performed other actions interacting with the website? Anything that can be of interest.
There are many reasons why websites go down. Often the error you are seeing in the browser gives you a good hint.
It's likely a 504 error when the website is loading and loading but never shows up or show up a 504 error page. Please proceed to our 504 troubleshooting page.
It's likely a 503 error when you see a "service unavailable" message or just a blank screen or a 503 error page. Please proceed to our 503 troubleshooting page. Provide PHP error logs with your question.
Report the exact time when the issue started to happen.
Is the error happening constantly, or is it more on/off? Have you got similar issues before?
Also see our general support tips on best practices to make your support request here successful.