Step by Step Guide: Connecting Postman to Salesforce via OAuth 2.0

If you work with Salesforce APIs, you know that testing endpoints can sometimes be the hardest part of the job, not because the logic is complex, but because authentication can be a headache. Hardcoding passwords is a security risk, and session IDs expire too quickly. The solution? OAuth 2.0 with Postman.

In this guide, I will walk you through the exact steps to bridge your Salesforce Org with Postman by setting up a External client App in Salesforce and configuring Postman correctly, you can generate an Access Token (for immediate API calls) and a Refresh Token (to stay connected indefinitely without re-logging in).

🛠 Prerequisites

• A Salesforce Account (Developer Edition or Sandbox recommended).
• Postman installed on your machine.
• Basic understanding of REST APIs.

1) Create a Connected App (New External Client App) in Salesforce

This acts as the "doorway" for Postman to enter Salesforce.

• Log in to Salesforce Setup (gear icon → Setup).

• In Quick Find, search for App Manager.

• Click New External Client App (top-right).

• Fill in:

  • External Client App Name

  • API Name

  • Contact Email

• Check Enable OAuth Settings.

  • Set Callback URL (Use the standard Postman callback)

https://oauth.pstmn.io/v1/callback

• In Selected OAuth Scopes, add:

  • Access and manage your data (api)

  • Perform requests on your behalf at any time (refresh_token, offline_access)

These scopes let your app call Salesforce APIs and get a refresh token.

• Save the external client app and wait ~10 minutes for it to fully propagate.

• Once saved, open the app’s detail page.

• Get SF_CLIENT_ID and SF_CLIENT_SECRET

On your external client app’s detail screen:

• Consumer Key → this is your SF_CLIENT_ID

• Consumer Secret → this is your SF_CLIENT_SECRET

Salesforce labels them Consumer Key and Consumer Secret respectively.

2) Setup Postman Settings

• In Postman, create a new http request.

• Go to the Authorization tab.

• Make sure no collection is selected in collections tab.

If you run OAuth from within a collection that has its own Auth settings:

• Postman may reuse or override tokens.

• It may try to use a stored callback URI and can lead to redirect mismatch or token assignment errors.

Option A, No Collection

• Don’t save the request in a collection.

• In Postman, leave the Collections panel unselected and run the request standalone.

Option B, Request-level Auth Only

• If you must save the request in a collection:

• Make sure Authorization Type = OAuth2.0 is set only at the request level and not at the collection level.

• Select OAuth 2.0 → Get New Access Token.

• Fill in:

  • Token Name: Personal API

  • Grant Type: Authorization Code(With PKCE)

  • Callback URL: Same as in your external client app or use Authorize using browser

  • Auth URL: https://login.salesforce.com/services/oauth2/authorize

  • Access Token URL: https://login.salesforce.com/services/oauth2/token

  • Client ID: your Consumer Key

  • Client Secret: your Consumer Secret

  • Code Challenge Method: SHA-256

  • Scope: api refresh_token offline_access

3) Generating the Tokens

• Click Get New Access Token.

• Log in and authorize.

• Click on Open Postman Option and make sure that your browser allow pop-ups.

This method uses Salesforce’s OAuth and gives you both tokens (access and refresh) in a GUI.

Postman can now use the refresh_token to automatically fetch a new access_token when the old one expires, preventing the need to log in again manually.

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