# Custom Actions vs. External Collections Think of **Custom Actions** as performing a task with an external API, while **External Collections** are used to bring data into your app. Custom Actions give your app more flexibility than External Collections because they run **instantly in response to a user action** and allow you to use the information in subsequent actions within your Adalo app. *** **Custom Actions** * Used when you want your app to *do something* with an external service through a REST API. * Send or receive data instantly when a user interacts with your app, such as pressing a button. * Great for performing actions like: * Sending form data to another system or database * Triggering a webhook in Make or Zapier * Getting real-time information from an external API (for example, sports scores, current weather, or stock prices) * Creating or updating data in another platform * Generating a shortened URL from a link shortener API * Best for getting a single piece of information for instant use. **External Collections** * Used when you want your app to *get a list of something* from an external service. * Retrieve and display lists or querying for individual records from an external database or API. * Commonly use filters or query parameters that reference Logged-In User properties so each user only sees their own data. * Best for reading and displaying information inside Adalo components, such as lists or detail screens. In short, use a **Custom Action** when you need to send or update data, and use an [**External Collection**](/integrations/external-collections-with-apis.md) when you need to show or query data. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://help.adalo.com/integrations/custom-actions/custom-actions-vs.-external-collections.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.