How can I create Twitter application?

To create a Twitter application, go to https://developer.twitter.com/en/portal/apps/new

Note: From July 2018, we need to apply for a developer account to create the Twitter app.

Step 1: If you do not have a developer account, it will redirect to the developer account section when you go to https://developer.twitter.com/en/portal/apps/new . If your developer account is approved, please go to Step 8.

Here select the “Professional > Build customized solutions in-house” option and click on “Get Started”.

Step 2:

Here we need to enter the basic info.

Step 3 :

Here we need to give more details.

Step 4 :

Describe the project. Here we need to explain how we are using the Twitter API.

A sample description is given below.

I am using a WordPress plugin to publish posts automatically from blog to Twitter. 
The plugin requires Twitter App to publish posts from WordPress to Twitter. 
For this, I must create an app and provide the app details such as API key, API secret, Access token, and Access token secret.’
When a new post, custom post type, or page is created at my WordPress site, it contains title, content, excerpt, images/videos, etc. When clicking the ‘publish’ button on the right side of the post/page/custom post type. 
The new post/page/custom-post-types will be published on the website as well as on Twitter.
The plugin allows to pre-fill the tweet content by allowing tweet formats such as POST_TITLE, PERMALINK, etc, which will be replaced by the blog post’s contents, and also attach image/video to the tweet as per settings.

Step 5 :

Here we need to review the entries and we can submit them on the next page.

Step 6 :

Do the email verification.

Step 7 :

In some cases, they will send an email for clarification.

In such a case we can provide a replay as given below.

After verification, they will approve the account and send an email.

Step 8 :

We can create the new app from https://developer.twitter.com/en/portal/apps/new

Here enter the app name and click on “Next”.

Step 9 :

Here save the API Key and API Key Secret. Please use these keys in the plugin twitter settings section.

Now click on the App settings button.

Step 10 :

Here click on the “Set up” button in the authentication section.

Step 11 :

Here enable the “OAuth 1.0a”, select the app permission “Read and write”, enter the callback url and website url.
Now save the settings.

Step 12 :

Now generate the Access Token and Secret.

Step 13 :

Save the Access token and Access Token Secret and use them in the plugin settings field.
We can see the permission of the app here.

Step 14 :

In the settings section, we can add the Application description, icon, and tell how the app is used. A sample description is given below.

I am using a WordPress plugin to publish posts automatically from blog to Twitter as a simple text message or as a text message with image/video. 
The plugin requires Twitter App to publish posts from WordPress to Twitter. 
For this, I must create an app and provide the app details such as API key, API secret, Access token, and Access token secret.

After entering the details, click on the “Save” button.

      Step 15: Elevated Access

All Twitter API access requires a developers account, which can be created quickly by signing up. Essential access  will be available immediately after signup, and Elevated access can be requested with a more detailed use case application.

With the recent changes to Twitter API ,you have to create a new App and Project with  Elevated access(Higher levels of access to the Twitter API for free with an approved application.)

Apply for Elevated access at https://developer.twitter.com/en/portal/products/elevated 

That’s it! The app is now ready to use.