@c0nman said:

Is the api down? I’m getting a 503 error

I sent an API request now.
It worked normally.
I'm in Brazil.

I have also some problems with filtering by genres (e.g. 99) and watch providers using discover. Only one result at the moment.

Getting the error too in the "Try it" section on the website

@c0nman said:

Is the api down? I’m getting a 503 error

Me too!!!! I think the API is down, yes!

I'm facing the same error message too, so I think the api is down

API works, RESPONDING button does not work. If you enter the line next to the button into the command line of the browser, then everything opens in JSON

@c0nman said:

Is the api down? I’m getting a 503 error

This error message can be for two reasons:

Code    HTTP    Status  Message  
9       503     Service offline: This service is temporarily offline, try again later.  
46      503     The API is undergoing maintenance. Try again later.  

The service was probably undergoing some maintenance.
Sending an API Request, twice via the browser at different times, I did not receive this response.

The service that is experiencing problems is the developers.
https://developers.themoviedb.org/3/getting-started/introduction
And yes, he's in trouble. It may be temporary.
Only for requests sent directly by developers.
Developers.themoviedb is hosted by https://stoplight.io/
This is the error response I get on developers.themoviedb:

Error: Network Error  
Check the developer tools console, it might have more information on the error.  
If you are using an Ad blocker, it is possible your Ad blocker is blocking the request.  

But if I use the URL directly in the browser I get the correct answer.