Create a custom connector from scratch


This topic is part of a tutorial series on creating and using custom connectors in Azure Logic Apps, Microsoft Power Automate, and Microsoft Power Apps. Make sure you read the custom connector overview to understand the process.

To create a custom connector, you must describe the API you want to connect to so that the connector understands the API's operations and data structures. In this topic, you create a custom connector from scratch, without using a Postman collection or an OpenAPI definition to describe the Azure Cognitive Services Text Analytics API sentiment operation (our example for this series). Instead, you describe the connector completely in the custom connector wizard.

For other ways to describe an API, go to the following topics:


You can currently create a custom connector from scratch in Power Automate and Power Apps. For Logic Apps, you must start with at least a basic OpenAPI definition or Postman collection.


Start the custom connector wizard

  1. Sign in to Power Apps or Power Automate.

  2. On the left pane, select Data > Custom connectors.

    Screenshot of Select custom connectors.

  3. Select New custom connector, and then select Create from blank.

    Screenshot of Create from blank.

  4. Enter a name for the custom connector, and then select Continue.

    Screenshot of the custom connector name.

    Parameter Value
    Custom connector title SentimentDemo

Step 1: Update general details

From this point, we'll show the Power Automate UI, but the steps are largely the same across the technologies. We'll point out any differences.

  1. On the General tab, do the following:

    • In the Description field, enter a meaningful value. This description will appear in the custom connector's details, and it can help others decide whether the connector might be useful to them.

    • Update Host to the address for the Text Analytics API. The connector uses the API host and the base URL to determine how to call the API.

    Screenshot of the custom connector General tab.

    Parameter Value
    Description Uses the Cognitive Services Text Analytics Sentiment API to determine whether text is positive or negative


    For more information about the option Connect via on-premises data gateway, go to Connect to on-premises APIs by using the data gateway.

Step 2: Specify authentication type

There are several options available for authentication in custom connectors. The Cognitive Services APIs use API key authentication, so that's what you specify for this tutorial.

  1. On the Security tab, under Authentication type, select API Key.

    Screenshot of Authentication type.

  2. Under API Key, specify a parameter label, name, and location. Specify a meaningful label, because this is displayed when someone first makes a connection with the custom connector. The parameter name and location must match what the API expects. Select Connect.

    Screenshot of API key parameters.

    Parameter Value
    Parameter label API key
    Parameter name Ocp-Apim-Subscription-Key
    Parameter location Header
  3. At the top of the wizard, make sure the name is set to SentimentDemo, and then select Create connector.

Step 3: Create the connector definition

The custom connector wizard gives you many options for defining how your connector functions, and how it's exposed in logic apps, flows, and apps. We'll explain the UI and cover a few options in this section, but we also encourage you to explore on your own.

Create an action

The first thing to do is create an action that calls the Text Analytics API sentiment operation.

  1. On the Definition tab, the left pane displays any actions, triggers (for Logic Apps and Power Automate), and references that are defined for the connector. Select New action.

    Screenshot of Definition tab - actions and triggers.

    There are no triggers in this connector. You can learn about triggers for custom connectors in Use webhooks with Azure Logic Apps and Power Automate.

  2. The General area displays information about the action or trigger that's currently selected. Add a summary, description, and operation ID for this action.

    Screenshot of Definition tab - general.

    Parameter Value
    Summary Returns a numeric score representing the sentiment detected
    Description The API returns a numeric score between 0 and 1. Scores close to 1 indicate positive sentiment, while scores close to 0 indicate negative sentiment.
    Operation ID DetectSentiment

    Leave the Visibility property set to none. This property for operations and parameters in a logic app or flow has the following options:

    • none: displayed normally in the logic app or flow
    • advanced: hidden under another menu
    • internal: hidden from the user
    • important: always shown to the user first
  3. The Request area displays information based on the HTTP request for the action. Select Import from sample.

    Screenshot of Definition tab - import from sample in the Request area.

  4. Specify the information necessary to connect to the API, specify the request body (provided after the following image), and then select Import. We provide this information for you, but for a public API, you typically get this information from documentation such as Text Analytics API (v2.0).

    Screenshot of Definition tab - import from sample.

    Parameter Value
    Verb POST
    URL <>
    Body Use the following JSON code
      "documents": [
          "language": "string",
          "id": "string",
          "text": "string"
  5. The Response area displays information based on the HTTP response for the action. Select Add default response.

    Screenshot of Definition tab - Add default response.

  6. Specify the response body, and then select Import. As we did for the request body, we provide this information for you following the image, but it's typically provided in the API documentation.

    Sreenshot of Definition tab - response.

     "documents": [
         "score": 0.0,
         "id": "string"
     "errors": [
         "id": "string",
         "message": "string"
  7. The Validation area displays any issues that are detected in the API definition. Check the status, and then in the upper-right corner of wizard, select Update connector.

    Screenshot of Definition tab - validation.

Update the definition

Now let's change a few things so that the connector is more friendly when someone uses it in a logic app, flow, or app.

  1. In the Request area, select body, and then select Edit.

    Screenshot of Edit request body.

  2. In the Parameter area, you now see the three parameters that the API expects: id, language, and text. Select id, and then select Edit.

    Screenshot of Edit request body id.

  3. In the Schema Property area, update values for the parameter, and then select Back.

    Screenshot of Edit schema property.

Parameter Value
Title ID
Description An identifier for each document that you submit
Default value 1
Is required Yes
  1. In the Parameter area, select language, select Edit, and then repeat the process that you used for id in steps 2 and 3 of this procedure, with the following values.

    Parameter Value
    Title Language
    Description The 2 or 4 character language code for the text
    Default value en
    Is required Yes
  2. In the Parameter area, select text, select Edit, and then repeat the process that you used for id in steps 2 and 3 of this procedure, with the following values.

    Parameter Value
    Title Text
    Description The text to analyze for sentiment
    Default value None
    Is required Yes
  3. In the Parameter area, select Back to take you back to the main Definition tab.

  4. In the upper-right corner of the wizard, select Update connector.

Step 4: (Optional) Use custom code support


  • This step is optional. You can complete the codeless experience for creating your connector by ignoring this step and going to Step 5: Test the connector.

  • Custom code support is available in public preview.

Custom code transforms request and response payloads beyond the scope of existing policy templates. Transformations include sending external requests to fetch additional data. When code is used, it will take precedence over the codeless definition. This means that the code will execute, and we won't send the request to the back end.

You can either paste in your code or upload a file with your code. Your code must:

  • Be written in C#.
  • Have a maximum execution time of five seconds.
  • Have a file size no larger than 1 MB.

For instructions and samples of writing code, go to Write code in custom connectors.

For frequently asked questions about custom code, go to Custom code FAQ.

  1. On the Code tab, insert your custom code by using one of the following options:

    • Copy/paste
    • Select the Upload button.

    If you choose to upload your custom code, only files with a .cs or .csx extension will be available.

    Screenshot of Upload your custom code.


    Currently, we only support syntax highlighting in the code editor. Make sure to test your code locally.

  2. After you paste or upload your code, select the toggle next to Code Disabled to enable your code. The toggle name changes to Code Enabled.

    You can enable or disable your code anytime. If the toggle is Code Disabled, your code will be deleted.

    Screenshot of Disable code message.

  3. Select the actions and triggers to apply to your custom code by selecting an option in the dropdown list. If no operation is selected, the actions and triggers are applied to all operations.

    Screenshot of Select actions and triggers.

Step 5: Test the connector

Now that you've created the connector, test it to make sure it's working properly. Testing is currently available only in Power Automate and Power Apps.


When using an API key, we recommend against testing the connector immediately after you create it. It can take a few minutes until the connector is ready to connect to the API.

  1. On the Test tab, select New connection.

    Screenshot of new connection.

  2. Enter the API key from the Text Analytics API, and then select Create connection.

    Screenshot of create connection.


    For APIs that require bearer authentication, add Bearer and one space before the API key.

  3. Return to the Test tab, and do one of the following:

    • In Power Automate, you're taken back to the Test tab. Select the refresh icon to make sure the connection information is updated.

      Screenshot of refresh connection.

    • In Power Apps, you're taken to the list of connections available in the current environment. On the left pane, select Data > Custom connectors. Choose the connector you created, and then go back to the Test tab.

      Screenshot of select custom connector.

  4. On the Test tab, enter a value for the text field (the other fields use the defaults that you set earlier), and then select Test operation.

    Screenshot of test operation.

  5. The connector calls the API, and you can review the response, which includes the sentiment score.

    Screenshot of connector response.

(For CLI users) Best practices

  • Download all your connectors, and use Git or any source code management system to save the files.

  • If there's an incorrect update, redeploy the connector by rerunning the update command with the correct set of files from the source code management system.

  • Test the custom connector and the settings file in a test environment before deploying in the production environment.

  • Always double-check that the environment and connector ID are correct.

Next steps

Now that you've created a custom connector and defined its behaviors, you can use the connector from:

You can also share a connector within your organization or get the connector certified so that people outside your organization can use it.

Provide feedback

We greatly appreciate feedback on issues with our connector platform, or new feature ideas. To provide feedback, go to Submit issues or get help with connectors and select your feedback type.