A private app is a way to connect a custom integration to a single HubSpot account using an access token. The app has a defined set of scopes that control which data and actions the token can use through the HubSpot API.
Teams use private apps when they build their own connection to HubSpot, for example a script that syncs orders from a store, or a data warehouse that reads deals each night. An admin creates the app in the account, chooses its scopes, such as read access to contacts or write access to deals, and receives an access token. Anyone who holds that token can make API calls with those scopes, so it must be treated like a password. HubSpot has been updating how apps are built, so the exact setup screen may differ in your account.
Scopes are the main control. A private app should have only the scopes it needs. An app that only reads deals does not need to write contacts or change settings. Broad scopes on a token that is stored in a shared document or a code repository are a serious security risk.
API calls from private apps count toward the account’s API rate limits. There are short-term limits on bursts of requests and a daily limit, and the exact numbers depend on your subscription. When an app hits a limit, its calls are rejected until the limit resets, which often means a sync stops partway through without anyone noticing.
Keep a simple register of private apps: what each one does, who owns it, where the token is stored and when it was last rotated. Remove apps that are no longer used, rotate tokens when a person with access leaves, and watch API usage so one app does not starve the others.
A wholesale distributor had four private apps, two built by an agency that no longer worked with them. One still held write access to contacts and companies. The admin confirmed nothing used it, deleted it, rotated the token on the main order sync app, and reduced its scopes to the three objects it actually wrote.
A private app connects to one HubSpot account and uses a static access token. A public app is built to be installed in many accounts and uses an authorization flow where each account grants access.
Further calls are rejected until the limit resets. Integrations usually fail quietly, so data stops syncing. Check API usage regularly and reduce unnecessary calls, for example by using webhooks instead of frequent polling where possible.
Ancil connects to HubSpot read-only in about 60 seconds. Nothing changes in your portal without your approval.