Salesforce Authenticate Username Password API

Salesforce.com (stylized as salesƒorce) is a cloud computing company headquartered in San Francisco, California. Though its revenue comes from a customer relationship management (CRM) product, Salesforce also tries capitalizing on commercial applications of social networking through acquisition.

When we develop an external application that needs to authenticate with Salesforce, you need to define it as a new connected app within the Salesforce organization that informs Salesforce of this new authentication entry point. 

Please create developer account first 

Use the following steps to create a new connected app.

1. From Setup, enter Apps in the Quick Find box, then select Apps and click New to start defining a connected app.
   
2. Enter the name of your application.
   
3. Enter the contact email information, as well as any other information appropriate for your application.
   
4. Select Enable OAuth Settings.
   
5. Enter a Callback URL. Depending on which OAuth flow you use, this is typically the URL that a user’s browser is redirected to after successful authentication. As this URL is used for some OAuth flows to pass an access token, the URL must use secure HTTP (HTTPS) or a custom URI scheme.
   
6. Add all supported OAuth scopes to Selected OAuth Scopes. These scopes refer to permissions given by the user running the connected app.
   
7. Enter a URL for Info URL. This is where the user can go for more information about your application.
   
8. Click Save. The Consumer Key is created and displayed, and the Consumer Secret is created (click the link to reveal it). 
   
   
   
   
   
   For Testing Plase change IP Relaxation to Relax IP Relaxation
   
   
   
    Please follow these step to test you Authentication
   
   Api URL:  https://login.salesforce.com/services/oauth2/token
   
   example POST man
   
      Congrats you  are done.