Bruno API Client | Blog & News

OAuth2 Callback URL and System Browser Support in Bruno

Written by Ganesh Patil | Feb 19, 2026

Bruno provides a System Browser option for OAuth 2.0 Authorization Code authentication, allowing you to use your default system browser instead of the embedded Electron browser window. This means saved passwords, 2FA extensions, and corporate SSO flows all work exactly as you'd expect.

Enabling System Browser

Global Configuration (Recommended)

If you want every collection in your workspace to use the system browser for OAuth2, enable it once from Preferences:

  1. Navigate to Preferences (located at the bottom of the left sidebar).
  2. Go to the General section.
  3. Enable Use System Browser for OAuth2.
  4. This setting applies to all collections by default.

Per-Request Configuration

You can also enable the system browser on individual requests, folders, or collections:

  1. Navigate to the Auth tab at the request, folder, or collection level and select OAuth 2.0 as the authentication method.
  2. Under Callback URL, check the Use System Browser for OAuth option.

The inbuilt browser option is selected by default, maintaining existing behaviour for users who prefer the embedded browser.

How It Works

When you select the System Browser option, the OAuth flow proceeds through five steps. The entire round-trip usually takes only a few seconds:

1
 

Authorization Request

Bruno builds the authorization URL (including state and PKCE code_challenge) and opens it in your default system browser.

2
 

User Authentication

You authenticate in your system browser with the OAuth provider — passwords, 2FA, SSO, and biometrics all work normally.

3
 

Callback Redirect

The authorization server redirects the browser to the configured callback URL (local or hosted), which extracts the authorization code and state parameters.

4
 

Deep Link Trigger

The callback page redirects to Bruno's custom URI scheme: bruno://app/oauth2/callback?code=…&state=…. The OS brings Bruno to the front and hands over the parameters.

5

Token Exchange

Bruno validates the state, performs the authorization code + PKCE token exchange directly with the provider, and stores the access & refresh tokens securely on your machine.

Privacy first: All OAuth data stays on your machine. Tokens are never processed or stored by Bruno's servers.

Understanding Callback URLs

The callback URL (also known as the redirect URI) is where the OAuth provider sends the browser after you finish the login and consent screens. It must be:

  • Reachable by the browser
  • Pre-registered in the provider's Authorised Redirect URIs list
  • Under your control (so you can read the code and state query parameters)

Bruno gives you two out-of-the-box choices:

Option Callback URL Who runs it Best for
Bruno Hosted https://oauth.usebruno.com/callback Bruno team Quick tests, zero setup
Local Server http://localhost:3000/oauth/callback You (one command) Offline, private, full control
Custom Hosted https://your-domain.com/oauth/callback Your team Enterprise, custom domains

Custom Callback Server

You may use your own hosted callback server or self-host one. Bruno will treat any configured callback URL as the OAuth redirect endpoint.

Option 1: Bruno's Hosted Callback Server

If you don't want to run anything locally, Bruno provides a hosted redirect endpoint. The server only forwards query parameters — it never sees or stores your tokens.

  1. In Bruno, set the Callback URL to https://oauth.usebruno.com/callback.
  2. Add that same URL to your OAuth provider's allowed redirect URIs.
  3. Make sure Use System Browser for OAuth is checked.

That's it — click Get Access Token and proceed as usual.

Option 2: Your Own Hosted Server

You can host your own callback server at your domain and point Bruno to it. This keeps the entire flow within your network.

  1. Host a callback server at your domain.
  2. Configure Bruno with your hosted callback URL, e.g. https://your-domain.com/oauth/callback.
  3. Add the same URL to your OAuth provider's allowed redirect URIs.

Option 3: Run a Local Callback Server

If you have Node.js installed, you can start a local callback server in seconds using the @usebruno/oauth2-callback-server npm package. It's a zero-config Express app that listens on port 3000 and forwards OAuth redirects to Bruno via the deep-link mechanism.

Install & Start

Terminal
# npx downloads and runs the latest version — no install needed
npx @usebruno/oauth2-callback-server
Expected output Starting OAuth2 callback server...
Server running on http://localhost:3000
Callback URL: http://localhost:3000/oauth/callback
Ready to receive OAuth redirects!
(Press Ctrl-C to stop)

Register the Callback with Your Provider

Add http://localhost:3000/oauth/callback to the Authorised Redirect URIs section of your OAuth app. For example:

  • Google — Cloud Console → APIs & Services → Credentials → OAuth 2.0 Client → Redirect URIs
  • Azure AD — App registrations → Authentication → Redirect URIs
  • GitHub — Settings → Developer settings → OAuth Apps → Callback URL

Ensure your OAuth provider allows localhost redirect URLs. Most providers do for development, but some may require explicit approval.

Configure Bruno

  1. Open the collection → Auth → OAuth 2.0.
  2. Set Grant Type to Authorization Code.
  3. Set Callback URL to http://localhost:3000/oauth/callback.
  4. Check Use System Browser for OAuth.
  5. Fill in the remaining fields (Authorization URL, Access Token URL, Client ID, Client Secret, Scope).

Obtain a Token

Click Get Access Token. Your default browser opens, you log in, approve the scopes, and the tab closes itself. Bruno stores the access and refresh tokens automatically.

(Optional) Change the Port

If port 3000 is already in use, pass a different port:

Terminal
npx @usebruno/oauth2-callback-server --port 8080

Then update the Callback URL in both Bruno and your OAuth provider to http://localhost:8080/oauth/callback.

About @usebruno/oauth2-callback-server

The @usebruno/oauth2-callback-server package is a lightweight, open-source Node.js server purpose-built for Bruno's OAuth2 system-browser flow.

Detail Value
npm @usebruno/oauth2-callback-server
Default port 3000
Callback path /oauth/callback
Custom port --port <number>
Requires Node.js (npx ships with npm 5.2+)

What it does:

  1. Listens for the OAuth provider's redirect on http://localhost:<port>/oauth/callback.
  2. Extracts the code and state query parameters.
  3. Immediately redirects the browser to bruno://app/oauth2/callback?code=…&state=…, handing the authorization code to Bruno via deep link.

No tokens are stored, logged, or transmitted by the server — everything stays local.

Conclusion

System-browser OAuth2 removes the biggest pain points of embedded-login flows while keeping setup trivial:

  • One command (npx @usebruno/oauth2-callback-server) gives you a fully local callback server, or paste https://oauth.usebruno.com/callback for zero setup.
  • A single checkbox in Bruno routes every OAuth2 Authorization Code flow through Chrome, Safari, Firefox, or Edge — so saved passwords, 2FA extensions, and corporate SSO pages work exactly as users expect.
  • Deep-link hand-off plus state and PKCE validation keeps the process secure; tokens never leave your machine.

Whether you're testing APIs against Google, Azure AD, Okta, GitHub, or a private IdP, enabling the system browser is the fastest way to reliable, frustration-free OAuth2 in Bruno.
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