Actor output schema

Learn how to define and present the output of your Actor.

The Actor output schema builds upon the schemas for the dataset and key-value store. It specifies where an Actor stores its output and defines templates for accessing that output. Apify Console uses these output definitions to display run results, and the Actor run's GET endpoint includes them in the output property.

Why output schema matters

Output schema is essential for:

AI agent integration: When agents use Actors through the MCP server or API, they need to know what results to expect. Without output schema, agents cannot effectively chain Actors or process results.
User experience: Clear output definitions help users understand what data they will receive before running an Actor.
API consumers: The output schema appears in the GET Run API response, enabling programmatic discovery of Actor outputs.

Define output schema

Even if your Actor produces no output, define an empty output schema. This tells users and AI agents that the Actor completed successfully with no output, rather than assuming the run failed.

Structure

Place the output configuration files in the .actor folder in the Actor's root directory.

You can organize the files using one of these structures:

Single configuration file

.actor/actor.json
{
    "actorSpecification": 1,
    "name": "files-scraper",
    "title": "Files scraper",
    "version": "1.0.0",
    "output": {
        "actorOutputSchemaVersion": 1,
        "title": "Output schema of the files scraper",
        "properties": { /* define your outputs here */ }
    }
}

Separate configuration files

.actor/actor.json
{
    "actorSpecification": 1,
    "name": "files-scraper",
    "title": "Files scraper",
    "version": "1.0.0",
    "output": "./output_schema.json"
}

.actor/output_schema.json
{
    "actorOutputSchemaVersion": 1,
    "title": "Output schema of the files scraper",
    "properties": { /* define your outputs here */ }
}

Definitions

The output schema defines the collections of keys and their properties. It allows you to organize and validate data stored by the Actor, making it easier to manage and retrieve specific records.

Output schema object definition

Property	Type	Required	Description
`actorOutputSchemaVersion`	integer	true	Specifies the version of output schema structure document. Currently only version 1 is available.
`title`	string	true	Title of the schema
`description`	string	false	Description of the schema
`properties`	Object	true	An object where each key is an output ID and its value is an Output object definition (see below).

Output object definition

Property	Type	Required	Description
`title`	string	true	The output's title, shown in the run's output tab if there are multiple outputs and in API as key for the generated output URL.
`description`	string	false	A description of the output. Only used when reading the schema (useful for LLMs).
`template`	string	true	Defines a URL template that generates the output link using `{{variable}}` syntax. See How templates work for details.

Available template variables

Variable	Type	Description
`links`	object	Contains quick links to most commonly used URLs
`links.publicRunUrl`	string	Public run url in format `https://console.apify.com/view/runs/:runId`
`links.consoleRunUrl`	string	Console run url in format `https://console.apify.com/actors/runs/:runId`
`links.apiRunUrl`	string	API run url in format `https://api.apify.com/v2/actor-runs/:runId`
`links.apiDefaultDatasetUrl`	string	API url of default dataset in format `https://api.apify.com/v2/datasets/:defaultDatasetId`
`links.apiDefaultKeyValueStoreUrl`	string	API url of default key-value store in format `https://api.apify.com/v2/key-value-stores/:defaultKeyValueStoreId`
`run`	object	Contains information about the run same as it is returned from the `GET Run` API endpoint
`run.containerUrl`	string	URL of a webserver running inside the run in format `https://<containerId>.runs.apify.net/`
`run.defaultDatasetId`	string	ID of the default dataset
`run.defaultKeyValueStoreId`	string	ID of the default key-value store
`storages`	object	Contains references to named storages defined in the Actor's storage configuration
`storages.datasets.<name>.apiUrl`	string	API URL of a named dataset in format `https://api.apify.com/v2/datasets/:datasetId`
`storages.keyValueStores.<name>.apiUrl`	string	API URL of a named key-value store in format `https://api.apify.com/v2/key-value-stores/:keyValueStoreId`

How templates work

Templates allow you to dynamically generate URLs that point to your Actor's output. When an Actor run completes, the Apify platform processes each template by:

Replacing {{variable}} placeholders with actual runtime values
Creating the final output URL from the interpolated template

The generated URL then appears in the Output tab of Apify Console and in the output property of the API response.

Template syntax

Templates use double curly braces {{variable}} for variable interpolation.

{{links.apiDefaultDatasetUrl}}/items becomes https://api.apify.com/v2/datasets/<dataset-id>/items
{{run.containerUrl}} becomes https://<container-id>.runs.apify.net/

You can access nested properties using dot notation (e.g., {{run.defaultDatasetId}}, {{links.publicRunUrl}}).

Examples

Linking default dataset

The following example Actor calls Actor.pushData() to store results in the default dataset:

main.js
import { Actor } from 'apify';
// Initialize the JavaScript SDK
await Actor.init();

/**
 * Store data in default dataset
 */
await Actor.pushData({ title: 'Some product', url: 'https://example.com/product/1', price: 9.99 });
await Actor.pushData({ title: 'Another product', url: 'https://example.com/product/2', price: 4.99 });

// Exit successfully
await Actor.exit();

To specify that the Actor is using output schema, update the .actor/actor.json file:

.actor/actor.json
{
    "actorSpecification": 1,
    "name": "Actor Name",
    "title": "Actor Title",
    "version": "1.0.0",
    "output": "./output_schema.json"
}

Then to specify that output is stored in the default dataset, create .actor/output_schema.json:

.actor/output_schema.json
{
    "actorOutputSchemaVersion": 1,
    "title": "Output schema of the Actor",
    "properties": {
        "results": {
            "type": "string",
            "title": "Results",
            "template": "{{links.apiDefaultDatasetUrl}}/items"
        }
    }
}

To show that the output is stored in the default dataset, the schema defines a property called results.

The title is a human-readable name for the output, shown in the Apify Console.

The template uses a variable {{links.apiDefaultDatasetUrl}}, which is replaced with the URL of the default dataset when the Actor run finishes.

Apify Console uses this configuration to display dataset data.

The Output tab will then display the contents of the dataset:

Output tab in Run

The GET Run API endpoint response will include an output property.

"output": {
    "results": "https://api.apify.com/v2/datasets/<dataset-id>/items"
}

Linking to key-value store

Similar to the example of linking to default dataset, the following example Actor calls Actor.setValue() to store files in the default key-value store:

main.js
import { Actor } from 'apify';
// Initialize the JavaScript SDK
await Actor.init();

/**
 * Store data in key-value store
 */
await Actor.setValue('document-1.txt', 'my text data', { contentType: 'text/plain' });
await Actor.setValue(`image-1.jpeg`, imageBuffer, { contentType: 'image/jpeg' });

// Exit successfully
await Actor.exit();

To specify that the Actor is using output schema, update the .actor/actor.json file:

.actor/actor.json
{
    "actorSpecification": 1,
    "name": "Actor Name",
    "title": "Actor Title",
    "version": "1.0.0",
    "output": "./output_schema.json"
}

Then to specify that output is stored in the key-value store, update .actor/output_schema.json:

.actor/output_schema.json
{
    "actorOutputSchemaVersion": 1,
    "title": "Output schema of the Actor",
    "properties": {
        "files": {
            "type": "string",
            "title": "Files",
            "template": "{{links.apiDefaultKeyValueStoreUrl}}/keys"
        }
    }
}

To show that the output is stored in the default key-value store, the schema defines a property called files.

The template uses a variable {{links.apiDefaultKeyValueStoreUrl}}, which is replaced with the URL of the default key-value store API endpoints when the Actor run finishes.

Apify Console uses this configuration to display key-value store data.

The Output tab will then display the contents of the key-value store:

Output tab in Run

The GET Run API endpoint response will include an output property.

"output": {
    "files": "https://api.apify.com/v2/key-value-stores/<key-value-store-id>/keys"
}

Linking dataset views and key-value store collections

This example shows a schema definition for a basic social media scraper. The scraper downloads post data into the dataset, and video and subtitle files into the key-value store.

After you define views and collections in dataset_schema.json and key_value_store.json, you can use them in the output schema.

Output schema complements dataset schema

The output schema defines where data is stored and how to access it. The dataset schema defines what fields each item contains, including descriptions and examples. Use both schemas together:

Output schema: Declares that results are in the default dataset
Dataset schema: Describes each field with title, description, and example

This combination gives AI agents complete information about your Actor's output structure.

.actor/output_schema.json
{
    "actorOutputSchemaVersion": 1,
    "title": "Output schema of Social media scraper",
    "properties": {
        "overview": {
            "type": "string",
            "title": "Results",
            "template": "{{links.apiDefaultDatasetUrl}}/items"
        },
        "subtitleFiles": {
            "type": "string",
            "title": "Subtitle files",
            "template": "{{links.apiDefaultKeyValueStoreUrl}}/keys?collection=subtitles"
        },
        "videoFiles": {
            "type": "string",
            "title": "Video files",
            "template": "{{links.apiDefaultKeyValueStoreUrl}}/keys?collection=videos"
        }
    }
}

The schema above defines one dataset output and two key-value store outputs. The dataset output links to the entire dataset. In Apify Console, this displays as a table with a selector that lets users switch between views defined in the dataset schema. The key-value store outputs link to collections defined in the key-value store schema.

If you add a view parameter to the dataset URL template, users still see the entire dataset in Apify Console, but the specified view is selected by default.

When a user runs the Actor in the Console, the UI will look like this:

Video files in Output tab

Use container URL to display chat client

In this example, an Actor runs a web server that provides a chat interface to an LLM. The conversation history is then stored in the dataset.

.actor/output_schema.json
{
    "actorOutputSchemaVersion": 1,

    "title": "Chat client output",
    "description": "Chat client provides interactive view to converse with LLM and chat history in dataset",
    "type": "object",

    "properties": {
        "clientUrl": {
            "type": "string",
            "title": "Chat client",
            "template": "{{run.containerUrl}}"
        },
        "chatHistory": {
            "type": "string",
            "title": "Conversation history",
            "template": "{{links.apiDefaultDatasetUrl}}/items"
        }
    }
}

In the schema above we have two outputs. The clientUrl output will return a link to the web server running inside the run. The chatHistory links to the default dataset and contains the history of the whole conversation, with each message as a separate item.

When the run in the Console, the user will then see this:

Chat in Output tab

Custom HTML as Actor run output

This example shows an output schema of an Actor that runs Cypress tests. When the run finishes, the Actor generates an HTML report and store it in the key-value store. You can link to this file and show it as an output:

.actor/output_schema.json
{
    "actorOutputSchemaVersion": 1,

    "title": "Cypress test report output",
    "description": "Test report from Cypress",
    "type": "object",

    "properties": {
        "reportUrl": {
            "type": "string",
            "title": "HTML Report",
            "template": "{{links.apiDefaultKeyValueStoreUrl}}/records/report.html"
        }
    }
}

The reportUrl in this case links directly to the key-value store record stored in the default key-value store.

When the run finishes, Apify Console displays the HTML report in an iframe:

HTML report in Output tab

Web crawler with multiple output types

This example shows a complete output schema for a web crawler Actor with multiple output types: crawled page data, errors, and files stored in key-value store collections.

.actor/output_schema.json
{
    "$schema": "https://apify-projects.github.io/actor-json-schemas/output.json?v=0.3",
    "actorOutputSchemaVersion": 1,
    "title": "Output schema of the Actor",
    "properties": {
        "crawlResults": {
            "type": "string",
            "title": "Crawl results",
            "template": "{{links.apiDefaultDatasetUrl}}/items"
        },
        "screenshots": {
            "type": "string",
            "title": "Screenshots",
            "template": "{{links.apiDefaultKeyValueStoreUrl}}/keys?collection=screenshots"
        },
        "downloadedFiles": {
            "type": "string",
            "title": "Downloaded files",
            "template": "{{links.apiDefaultKeyValueStoreUrl}}/keys?collection=downloaded-files"
        },
        "htmlSnapshots": {
            "type": "string",
            "title": "HTML snapshots",
            "template": "{{links.apiDefaultKeyValueStoreUrl}}/keys?collection=html-snapshots"
        },
        "crawlErrors": {
            "type": "string",
            "title": "Errors",
            "template": "{{storages.datasets.errors.apiUrl}}/items"
        }
    }
}

Each output includes a description explaining what the data contains. This metadata helps AI agents understand the Actor's capabilities and select the appropriate output for their needs.

Actor with no output

If your Actor produces no output (for example, an integration Actor that performs an action), users might see the empty Output tab and think the Actor failed. To avoid this, specify that the Actor produces no output.

You can specify that the Actor produces no output and define an output schema with no properties:

.actor/output_schema.json
{
    "actorOutputSchemaVersion": 1,

    "title": "Send mail output",
    "description": "Send mail Actor does not generate any output.",
    "type": "object",
    "properties": {}
}

When the output schema contains no properties, Apify Console displays the Log tab instead of the Output tab.