Key Takeaways
- An app ID names your application to a platform; it is safe to show in client code and URLs.
- Every platform has its own: Apple App ID and bundle ID, Android applicationId, Meta App ID, Discord application ID, Slack App ID, Microsoft application (client) ID.
- The app ID is never the credential. Secrets, tokens and keys prove ownership and must stay on your server.
- On Android the applicationId cannot change once the app is published; on Apple the bundle ID is fixed per App ID.
What Is an App ID?
An app ID (application ID) is the identifier a platform assigns to your application so that its APIs, app stores and sign-in screens know which app is talking to them. When a user taps Log in with Facebook, installs your iPhone app or authorises a Discord bot, the platform looks up the app ID to show your app's name and icon, apply its permissions and route callbacks to the right place.
The important property is that an app ID is public. It appears in your mobile app bundle, in OAuth URLs and in page source. What keeps your app safe is a separate credential - an app secret, client secret, bot token or signing key - that only your server holds.
Where to Find the App ID on Each Platform
| Platform | What it is called | Looks like | Where to find it |
|---|---|---|---|
| Apple (iOS, macOS) | App ID / Bundle ID | TEAMID.com.company.app | Apple Developer > Certificates, Identifiers & Profiles > Identifiers |
| Android | applicationId (package name) | com.company.app | build.gradle, and the Play Console app page |
| Meta (Facebook, Instagram, WhatsApp) | App ID | A 15-16 digit number | Meta for Developers > your app > App settings > Basic |
| Discord | Application ID (also the OAuth2 client ID) | A 17-20 digit snowflake | Developer Portal > your app > General Information |
| Slack | App ID | A0123456789 | api.slack.com/apps > your app > Basic Information |
| Microsoft (Entra ID, Teams) | Application (client) ID | A GUID | Azure portal > App registrations > Overview |
| Google (OAuth) | Client ID | ...apps.googleusercontent.com | Google Cloud console > APIs & Services > Credentials |
| Telegram (MTProto clients) | api_id | A short number | my.telegram.org > API development tools |
Telegram bots are the exception: they have no app ID, only a bot token from @BotFather, which is a secret. You can check one with the Telegram bot token checker.
App ID vs Bundle ID, Client ID and API Key
Platforms use several identifiers that are easy to mix up:
- Bundle ID (Apple) is the reverse-domain string you choose, such as
com.acme.shop. Apple's App ID is that string prefixed with your Team ID, and it carries the app's capabilities (push, Sign in with Apple). - Client ID is the OAuth name for the same idea. On Discord and Microsoft the client ID is the application ID; on Slack they are two different values.
- API key varies: some are public identifiers restricted by domain or app, others are secrets. Treat any key you did not deliberately publish as a secret.
- App secret, client secret, token are always private. They prove the request comes from you, and anyone holding one can act as your app.
Rules That Catch People Out
- You usually cannot change it. Android's
applicationIdmust stay the same for the life of a published app, or the store treats it as a different app. An Apple bundle ID is fixed to its App ID. - Test and production apps differ. Meta, Discord and Slack apps each have their own ID; a webhook or OAuth redirect set up on the test app will not fire for the live one.
- A wrong ID fails quietly. Using the app ID of another app typically shows the wrong name on the consent screen or returns an invalid-client error, not a clear message - see the platform error code directory for the exact responses.
App IDs and Chatbots
Connecting a chatbot to a messaging channel almost always starts with an app registration: a Meta app for WhatsApp, Messenger and Instagram, a Discord application for a Discord bot, a Slack app for Slack, an Entra app for Microsoft Teams. The app ID tells the platform which bot is installed; the secret or token lets your bot server call the API. For Discord, the permissions calculator turns an application ID into a ready bot invite link.
Frequently Asked Questions
What does app ID mean?
Is an app ID secret?
Where do I find my Facebook or Meta App ID?
What is the difference between an app ID and a bundle ID?
Is the client ID the same as the app ID?
Can I change my app ID?
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