ExTda helps Elixir users use the TDAmeritrade API.
To use this, set the TDA_CLIENT_ID environment variable to your developer Client ID. .envrc.example is an example file that, once renamed to just .envrc, can be used with direnv.
To get your developer Client ID sign in at https://developer.tdameritrade.com with your TDAmeritrade brokerage account and go to the My Apps tab. Create an app with the callback url of https://127.0.0.1:4000. The Client ID here is what you need.
To use ExTda, make sure .envrc is updated with your Client ID, and generate self-signed certificates for a local https server in the root directory:
openssl req -newkey rsa:4096 -x509 -sha256 -days 365 -nodes -out localhost.crt -keyout localhost.key
Finally, use iex -S mix to start up an elixir repl, which also starts a local https server on port 4000. Visit https://12.0.0.1:4000 and TDAmeritrade should ask you to log in. Log in with your brokerage account, allow the permissions warning, and you will be redirected back to https://12.0.0.1:4000?code=... which should do the rest for you. At this point the rest of the functions in module ExTda.Client should work. You can run ExTda.Client.get_access_token/0 which, if you get a token, means things are working. In order to get a token from that the refresh_token must be valid.