api redirect url Best Practices and Considerations

When setting up an API redirect URL, it's essential to keep it secure. This means using HTTPS instead of HTTP, as it encrypts the data being transmitted.

A well-structured API redirect URL should be simple and easy to read. This makes it easier for developers to understand and implement the redirect.

The redirect URL should also be flexible and adaptable to different scenarios. This can be achieved by using query parameters to pass variables and dynamic values.

A good practice is to keep the redirect URL as short as possible, while still conveying the necessary information. This makes it easier to manage and maintain the API redirect.

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A URI is a crucial part of the API redirect URL process.

It's the location where the authentication server sends the user after successful authorization and access token issuance.

In a production web application, the redirect URI is often a public endpoint where your app is running, like https://contoso.com/auth-response.

This endpoint should be a secure location that can handle incoming requests from the authentication server.

During development, it's common to also add the endpoint where you run your app locally, like https://127.0.0.1/auth-response or http://localhost/auth-response.

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The purpose of a redirect URI is to specify the endpoint where your application or web page receives authorization responses from an authentication server. This is a critical security measure to ensure that tokens and other sensitive data are sent to a trusted location.

For Microsoft Entra applications, redirect URIs must begin with the scheme https, with exceptions for some localhost redirect URIs. This is a strict requirement to prevent unauthorized access to sensitive data.

You should add a redirect URI to your app registration if your application uses OAuth 2.0 authorization code flow, OAuth 2.0 client credentials flow, OAuth 2.0 implicit grant flow, OpenID Connect, or Single sign-on SAML protocol. If you're using Native Authentication, OAuth 2.0 device code flow, OAuth 2.0 On-Behalf-Of flow, or OAuth 2.0 Resource owner password credential flow, you don't need to add redirect URIs.

Here's a list of authorization protocols that require a redirect URI:

Redirect URIs are case-sensitive and must match the case of the URL path of your running application. This means that if your application is running on a URL with a specific case (e.g., https://example.com), your redirect URI must also have the same case.

You need to add redirect URIs to your app registration for security reasons, as the authentication server won't redirect users or send tokens to a URI that isn't added to the app registration.

You must add redirect URIs to your app registration if your application is using OAuth 2.0 authorization code flow, OAuth 2.0 client credentials flow, OAuth 2.0 implicit grant flow, OpenID Connect, or Single sign-on SAML protocol.

For example, if you're building an application that uses OAuth 2.0 authorization code flow, you need to add the redirect URI to your app registration.

You don't need to add redirect URIs to your app registration if your application is using Native Authentication, OAuth 2.0 device code flow, OAuth 2.0 On-Behalf-Of flow, OAuth 2.0 Resource owner password credential flow, Windows Integrated Auth Flow, or SAML 2.0 Identity Provider (IdP) for Single Sign On.

The maximum number of redirect URIs you can add to an app registration varies depending on the type of accounts being signed in. For Microsoft work or school accounts in any organization's Microsoft Entra tenant, the maximum number of redirect URIs is 256.

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Here's a table showing the maximum number of redirect URIs you can add to an app registration:

Always add redirect URIs to the application object only, and never add redirect URI values to a service principal because these values could be removed when the service principal object syncs with the application object.

You need to add redirect URIs to your app registration for security reasons, as the authentication server won't redirect users or send tokens to a URI that isn't added to the app registration.

Whether you should add a redirect URI depends on the authorization protocol your application uses, specifically OAuth 2.0 authorization code flow, OAuth 2.0 client credentials flow, OAuth 2.0 implicit grant flow, OpenID Connect, or Single sign-on SAML protocol.

To configure your redirect URIs, you must enable a public client flow configuration if your application contains one or multiple redirect URIs in your app registration.

Redirect URIs must begin with the scheme https, with exceptions for some localhost redirect URIs, and are case-sensitive, meaning they must match the case of the URL path of your running application.

The maximum number of redirect URIs is 256 for Microsoft work or school accounts in any organization's Microsoft Entra tenant, and 100 for personal Microsoft accounts and work and school accounts. Each redirect URI can be up to 256 characters long.

Always add redirect URIs to the application object only, as adding them to the service principal object can lead to them being removed due to sync operations.

Mobile and desktop applications require specific redirect URI configurations.

To add a redirect URI to your app registration for a mobile or desktop application, you should enable the public client flow configuration.

For iOS and macOS apps, excluding certain scenarios, you should add the redirect URI in the iOS/macOS platform.

For Android apps, you should add the redirect URI in the Android platform.

If you're building an app that runs natively on a mobile device or desktop machine, you should add the redirect URI in the Mobile and desktop applications platform.

Here's a table to help you determine which platform to use based on your app's type and programming languages:

If you're building an iOS app using open source SDKs (AppAuth), cross-plat tech (Flutter), or implementing OAuth protocols directly, use the Mobile and desktop applications platform to add a redirect URI.

Redirect URIs must begin with the scheme https, with exceptions for some localhost redirect URIs. This is a security requirement to ensure that authentication requests are sent over a secure connection.

You should always add redirect URIs to the application object only, as adding them to the service principal object can cause them to be removed during sync operations.

Redirect URIs are case-sensitive and must match the case of the URL path of your running application. This means that if your application's URL is in lowercase, your redirect URI should also be in lowercase.

The maximum number of redirect URIs you can add to an app registration is 256, with a maximum URI length of 256 characters. This is a security restriction to prevent brute-force attacks.

You don't need to add redirect URIs to your app registration if your application is using Native Authentication, OAuth 2.0 device code flow, or Windows Integrated Auth Flow.

The following characters are not allowed in redirect URIs: !, $, ', (, ), ,;, and Internationalized Domain Names. This is to prevent potential security vulnerabilities.

To ensure a smooth API redirect URL experience, it's essential to understand the limits and restrictions that come with it. The maximum number of redirect URIs you can add to an app registration varies depending on the type of accounts being signed in. For Microsoft work or school accounts in any organization's Microsoft Entra tenant, you can add up to 256 redirect URIs.

The maximum number of redirect URIs is capped at 256 for security reasons. If your scenario requires more redirect URIs than this, consider using the state parameter approach as a solution. You can use a maximum of 256 characters for each redirect URI you add to an app registration.

The case sensitivity of redirect URIs is also worth noting. They are case-sensitive and must match the case of the URL path of your running application. This means that if your app's URL is https://example.com, you should add https://example.com as a redirect URI, not https://Example.com.

Redirect URIs also have some specific formatting requirements. They must begin with the scheme https, with exceptions for some localhost redirect URIs. They don't support special characters like !, $, ', (, ), and ;, nor do they support Internationalized Domain Names.

HTTPS is the supported scheme for all HTTP-based redirect URIs. This means you can use the HTTPS scheme (https://) for any redirect URI.

For example, a redirect URI like https://contoso.com is valid, while a similar one like http://contoso.com is not.

You can also use the HTTPS scheme for more specific redirect URIs, such as https://contoso.com/abc/response-oidc, which is also valid.

However, HTTP is only supported for localhost URIs, and should be used only during active local application development and testing.

For instance, http://localhost is a valid redirect URI, but http://localhost/abc is also valid, even though it includes a path.

Here's a summary of the supported schemes:

http URI schemes are acceptable for localhost redirect URIs because the redirect never leaves the device.

For development purposes, it's essential to differentiate localhost redirect URIs using the path component of the URI, not just the port number.

To register multiple redirect URIs on localhost, use a different path for each, such as http://localhost/MyWebApp and http://localhost/MyNativeApp.

The IPv6 loopback address ([::1]) isn't currently supported for localhost redirect URIs.

Here are some key things to keep in mind when working with localhost redirect URIs:

Redirect URIs that contain a path segment are not appended with a trailing slash in the response, while those without a path segment are returned with a trailing slash ('/') in the response, unless the response mode is fragment.

To build and configure URIs, you need to understand the different types of authorization protocols your application uses. If your application is using OAuth 2.0 authorization code flow, OAuth 2.0 client credentials flow, OAuth 2.0 implicit grant flow, OpenID Connect, or Single sign-on SAML protocol, you must add redirect URIs to your app registration.

You should add redirect URIs to the application object only, not to a service principal, as these values could be removed when the service principal object syncs with the application object. Always ensure that redirect URIs begin with the scheme https, with exceptions for some localhost redirect URIs.

The type of redirect URI you should add depends on the platform you're building your application on. For example, if you're building an iOS or macOS app, you should add the redirect URI in the IOS/macOS platform. If you're building an Android app, you should add the redirect URI in the Android platform.

Here's a summary of the platforms to add redirect URIs in App Registration:

Remember to enable a public client flow configuration if your application contains one or multiple redirect URIs in your app registration.

URI rewrites and redirects are essential for managing API endpoints. They allow you to modify the URL of a request before it reaches the upstream server, providing a more subtle user experience compared to redirects.

A URL rewrite modifies the URL before the request reaches the upstream server, giving the client no indication that the URL was modified. This can be achieved by changing the value of 'type' to 'url-rewrite' in the YAML configuration.

For example, if you make a call to an endpoint in the '/v1/' directory, the response is sent from the '/v2/' endpoint, even though the requested URL was '/v1/list?accountId=12345&active=true'.

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You should use a state parameter if you have several subdomains and your scenario requires that, upon successful authentication, you redirect users to the same page from which they started.

The state parameter is helpful in this approach because it allows you to send application-specific parameters, such as subdomain URL where the user originated or branding information, to the redirect URI.

To use a state parameter, create a "shared" redirect URI per application to process the security tokens you receive from the authorization endpoint.

When using a state parameter, guard against CSRF protection as specified in section 10.12 of RFC 6749.

The state parameter includes all the information needed for the application to render the correct experience for the user, that is, construct the appropriate application state.

The Microsoft Entra authorization endpoint strips HTML from the state parameter, so make sure you aren't passing HTML content in this parameter.

When Microsoft Entra ID sends a response to the "shared" redirect URI, it sends the state parameter back to the application.

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The application can then use the value in the state parameter to determine which URL to further send the user to.

Here are the steps to use a state parameter:

Note that using a state parameter comes with some security risks, such as the open redirector threat described in RFC 6819. To mitigate this risk, the client must protect these parameters by encrypting the state or verifying it by some other means, like validating the domain name in the redirect URI against the token.

Creating Gateway is a crucial step in setting up API Gateway. To create a gateway, go to API Gateway Service in AWS and click on Create API.

Select REST API or HTTP API, and in this demo, we're choosing REST API. Give your API a name and Create API. Now, create a resource and enable CORS for testing.

To create a method, choose integration type as Lambda Function and switch on the lambda proxy integration switch. Select your lambda function and click on Create method.

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Here's a summary of the steps to create a gateway:

Once you've created your gateway, you can deploy it by clicking on Deploy API button and selecting/create a stage. This will give you the Invoke URL for your API, which you can use to test it.

URL rewrites are a subtle way to modify URLs before a request reaches the upstream server, giving the client no indication that the URL was changed.

You can achieve this by changing the type of an API Route Migration expression to url-rewrite and removing the status code. This will allow you to redirect requests from one endpoint to another without modifying the URL at the client level.

For example, if you have an API Route Migration expression that rewrites the URL from /v1/list to /v2/list, the client will receive a response from the /v2/list endpoint, even though the requested URL was /v1/list.

Using ngrok for serverless redirects and rewrites is another option, allowing you to create a single cloud endpoint on your root domain and use Traffic Policy actions to establish routes using composable patterns. This approach eliminates the need for additional infrastructure and only charges you for what you use.

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To register your redirect URL, you need to sign in to the Developer Console and choose Open for your application. If needed, you can add an application from the Applications page.

You must add a redirect URI to your app registration if your application is using OAuth 2.0 authorization code flow, OAuth 2.0 client credentials flow, OAuth 2.0 implicit grant flow, OpenID Connect, or Single sign-on SAML protocol.

The redirect URL is the endpoint where your application or web page receives authorization responses from Square, and it must use HTTPS. Your endpoint must be able to process the GET authorization response and securely store the access and refresh tokens and the code_verifier if you're using the PKCE flow.

The following parameters can be used in the authorization URL for the code flow, PKCE flow, or both: client_id, scope, session, state, code_challenge, redirect_uri, and locale.

Here are the restrictions of redirect URIs for Microsoft Entra applications:

The type of your application determines where to add the redirect URI in App Registration. For example, an iOS or macOS app should add the redirect URI in the IOS/macOS platform, while an Android app should add it in the Android platform.

You should add a redirect URI to your app registration if your application uses OAuth 2.0 authorization code flow, OAuth 2.0 client credentials flow, OAuth 2.0 implicit grant flow, OpenID Connect, or Single sign-on SAML protocol.

However, if your application uses Native Authentication, OAuth 2.0 device code flow, OAuth 2.0 On-Behalf-Of flow, OAuth 2.0 Resource owner password credential flow, or Windows Integrated Auth Flow, you don't need to add redirect URIs.

Always add redirect URIs to the application object only, never to a service principal, as these values could be removed when the service principal object syncs with the application object.

Here are the authorization protocols that require redirect URIs in the application object:

You can add query parameters to redirect URIs for applications that only sign in users with work or school accounts.

A permanent redirect should return a 301 status code, while a temporary redirect can return a 302 or 307 status code.

In order to successfully register your redirect URL, you'll need to follow a few specific steps. You must use HTTPS for your redirect endpoint, as this is a requirement for both the Square Sandbox environment and production environment.

The authentication server won't redirect users or send tokens to a URI that isn't added to the app registration, so it's essential to register your redirect URL correctly. If the redirect URI specified in the login request doesn’t match any of the redirect URIs you have added in your application, you'll receive an error message.

You should add a redirect URI to your app registration if your application uses OAuth 2.0 authorization code flow, OAuth 2.0 client credentials flow, OAuth 2.0 implicit grant flow, OpenID Connect, or Single sign-on SAML protocol.

Native Authentication, OAuth 2.0 device code flow, OAuth 2.0 On-Behalf-Of flow, OAuth 2.0 Resource owner password credential flow, Windows Integrated Auth Flow, and SAML 2.0 Identity Provider (IdP) for Single Sign On do not require redirect URIs in your app registration.

To register your redirect URL, sign in to the Developer Console and choose Open for your application. If needed, you can add an application from the Applications page. At the top of the page, choose the Sandbox (for testing) or Production environment. In the left pane, choose OAuth.

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