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If, after you have registered your app for App Check, you want to run your
app in an environment that App Check would normally not classify as valid,
such as locally during development, or from a continuous integration (CI)
environment, you can create a debug build of your app that uses the
App Check debug provider instead of a real attestation provider.
Use the debug provider on localhost
To use the debug provider while running your app from localhost (during
development, for example), do the following:
In your debug build, enable debug mode by setting
self.FIREBASE_APPCHECK_DEBUG_TOKEN to true before you initialize
App Check. For example:
self.FIREBASE_APPCHECK_DEBUG_TOKEN=true;firebase.appCheck().activate(/* site key or provider */);
Visit your web app locally and open the browser’s developer tool. In the
debug console, you’ll see a debug token:
AppCheck debug token: "123a4567-b89c-12d3-e456-789012345678". You will
need to safelist it in the Firebase console for it to work.
In the App Check section
of the Firebase console, choose Manage debug tokens from your app's
overflow menu. Then, register the debug token you logged in the previous
step.
After you register the token, Firebase backend services will accept it as valid.
Because this token allows access to your Firebase resources without a
valid device, it is crucial that you keep it private. Don't commit it to a
public repository, and if a registered token is ever compromised, revoke it
immediately in the Firebase console.
This token is stored locally in your browser and will be used whenever you use
your app in the same browser on the same machine. If you want to use the
token in another browser or on another machine, set
self.FIREBASE_APPCHECK_DEBUG_TOKEN to the token string instead of true.
Use the debug provider in a CI environment
To use the debug provider in a continuous integration (CI) environment, do the following:
In the App Check section
of the Firebase console, choose Manage debug tokens from your app's
overflow menu. Then, create a new debug token. You'll need the token in the
next step.
Because this token allows access to your Firebase resources without
a valid device, it is crucial that you keep it private. Don't commit it to a
public repository, and if a registered token is ever compromised, revoke it
immediately in the Firebase console.
Add the debug token you just created to your CI system's secure key store
(for example, GitHub Actions' encrypted secrets
or Travis CI's encrypted variables).
If necessary, configure your CI system to make your debug token available
within the CI environment as an environment variable. Name the variable
something like APP_CHECK_DEBUG_TOKEN_FROM_CI.
In your debug build, enable debug mode by setting
self.FIREBASE_APPCHECK_DEBUG_TOKEN to the value of the debug token
environment variable before you import App Check. For example:
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-22 UTC."],[],[],null,["If, after you have registered your app for App Check, you want to run your\napp in an environment that App Check would normally not classify as valid,\nsuch as locally during development, or from a continuous integration (CI)\nenvironment, you can create a debug build of your app that uses the\nApp Check debug provider instead of a real attestation provider.\n| **Warning:** The debug provider allows access to your Firebase resources from unverified devices. **Don't** use the debug provider in production builds of your app, and **don't** share your debug builds with untrusted parties.\n\nUse the debug provider on localhost\n\nTo use the debug provider while running your app from `localhost` (during\ndevelopment, for example), do the following:\n| **Warning:** *Do not* try to enable `localhost` debugging by adding `localhost` to reCAPTCHA's allowed domains. Doing so would allow anyone to run your app from their local machines!\n\n1. In your debug build, enable debug mode by setting\n `self.FIREBASE_APPCHECK_DEBUG_TOKEN` to `true` before you initialize\n App Check. For example:\n\n Web \n\n self.FIREBASE_APPCHECK_DEBUG_TOKEN = true;\n initializeAppCheck(app, { /* App Check options */ });\n\n Web \n\n self.FIREBASE_APPCHECK_DEBUG_TOKEN = true;\n firebase.appCheck().activate(/* site key or provider */);\n\n | **Note:** In Firebase Web SDK versions before v9, `self.FIREBASE_APPCHECK_DEBUG_TOKEN` is read at import time, and not at initialization/activation time. This required it to be set in `index.html` before the code bundle is loaded. To avoid this restriction, upgrade to v9.\n2. Visit your web app locally and open the browser's developer tool. In the\n debug console, you'll see a debug token:\n\n ```\n AppCheck debug token: \"123a4567-b89c-12d3-e456-789012345678\". You will\n need to safelist it in the Firebase console for it to work.\n ```\n3. In the [**App Check**](//console.firebase.google.com/project/_/appcheck) section\n of the Firebase console, choose **Manage debug tokens** from your app's\n overflow menu. Then, register the debug token you logged in the previous\n step.\n\nAfter you register the token, Firebase backend services will accept it as valid.\n\nBecause this token allows access to your Firebase resources without a\nvalid device, it is crucial that you keep it private. Don't commit it to a\npublic repository, and if a registered token is ever compromised, revoke it\nimmediately in the Firebase console.\n\nThis token is stored locally in your browser and will be used whenever you use\nyour app in the same browser on the same machine. If you want to use the\ntoken in another browser or on another machine, set\n`self.FIREBASE_APPCHECK_DEBUG_TOKEN` to the token string instead of `true`.\n\nUse the debug provider in a CI environment\n\nTo use the debug provider in a continuous integration (CI) environment, do the following:\n\n1. In the [**App Check**](//console.firebase.google.com/project/_/appcheck) section\n of the Firebase console, choose **Manage debug tokens** from your app's\n overflow menu. Then, create a new debug token. You'll need the token in the\n next step.\n\n Because this token allows access to your Firebase resources without\n a valid device, it is crucial that you keep it private. Don't commit it to a\n public repository, and if a registered token is ever compromised, revoke it\n immediately in the Firebase console.\n\n2. Add the debug token you just created to your CI system's secure key store\n (for example, GitHub Actions' [encrypted secrets](https://docs.github.com/en/actions/reference/encrypted-secrets)\n or Travis CI's [encrypted variables](https://docs.travis-ci.com/user/environment-variables/#defining-encrypted-variables-in-travisyml)).\n\n3. If necessary, configure your CI system to make your debug token available\n within the CI environment as an environment variable. Name the variable\n something like `APP_CHECK_DEBUG_TOKEN_FROM_CI`.\n\n4. In your debug build, enable debug mode by setting\n `self.FIREBASE_APPCHECK_DEBUG_TOKEN` to the value of the debug token\n environment variable before you import App Check. For example:\n\n Web \n\n self.FIREBASE_APPCHECK_DEBUG_TOKEN = process.env.APP_CHECK_DEBUG_TOKEN_FROM_CI;\n initializeAppCheck(app, { /* App Check options */ });\n\n Web \n\n self.FIREBASE_APPCHECK_DEBUG_TOKEN = process.env.APP_CHECK_DEBUG_TOKEN_FROM_CI;\n firebase.appCheck().activate(/* site key or provider */);\n\nWhen your app runs in a CI environment, Firebase backend services will accept\nthe token it sends as valid."]]
