How to Use APIs in Zapier Steps: Webhooks by Zapier and API by Zapier

A practical field guide from Automation Ace.

How to Use APIs in Zapier Steps: Webhooks by Zapier and API by Zapier

Zapier supports over 10,000 app integrations through native connectors, but there are always situations where a specific endpoint, data source, or service does not have a Zapier connector — or where the native connector does not expose the specific API action you need. For these cases, Zapier provides two built-in tools for making direct API calls inside a Zap: Webhooks by Zapier and API by Zapier. Both allow you to send HTTP requests to any REST API, but they serve different use cases and have different capabilities. This guide covers both tools, when to use each, and how to set up authenticated API calls inside your Zaps.

Webhooks by Zapier: The Original HTTP Action

Webhooks by Zapier is Zapier's long-standing tool for sending and receiving HTTP requests. As an action step, it supports GET, POST, PUT, and DELETE requests to any URL. As a trigger step, it provides a unique Catch Hook URL that receives inbound webhook payloads from external systems and starts a Zap. For a foundational explanation of how webhooks work, see what is a webhook.

As an outbound action, Webhooks by Zapier is configured with:

• Method: GET, POST, PUT, PATCH, or DELETE
• URL: The API endpoint to call, which can include data mapped from earlier steps
• Data: The request body for POST/PUT/PATCH requests — can be sent as form data or JSON
• Headers: Custom headers including Authorization headers for API key or Bearer token authentication
• Basic Auth: Username and password fields for Basic authentication
• Unflatten: Controls whether nested key structures in the data field are converted to nested JSON objects

Webhooks by Zapier returns the full API response body, status code, and headers as output fields available to subsequent steps. If the API returns a JSON object, each top-level key is available as a separate output field. For a deeper explanation of how to configure authenticated API requests in Zapier, see API authentication for automation.

API by Zapier: A More Flexible HTTP Action

API by Zapier (zapier.com/apps/api-by-zapier) is a newer Zapier-native tool designed to make it easier to call APIs with more complex authentication patterns and request configurations than Webhooks by Zapier handles cleanly. It provides a more guided interface for setting up API calls, with dedicated fields for different authentication schemes and cleaner handling of JSON request bodies.

Key differences between API by Zapier and Webhooks by Zapier:

• Authentication handling: API by Zapier provides structured fields for OAuth 2.0, API key, and custom header authentication — reducing the manual header construction required in Webhooks by Zapier
• JSON body construction: API by Zapier makes it easier to build properly structured JSON request bodies, including nested objects, without the flat key-value structure of the Webhooks action
• Response parsing: Both tools parse JSON responses, but API by Zapier's output mapping can be more explicit
• Error handling: API by Zapier surfaces API error responses more clearly in the Zap run history

API by Zapier is the recommended choice when you are calling an API with OAuth 2.0 authentication, when the request body requires nested JSON structure, or when the cleaner interface reduces configuration errors for less technical team members maintaining the Zap.

When to Use Webhooks by Zapier vs. API by Zapier

Use Webhooks by Zapier when:

• The API uses simple authentication — API key in a header, Basic auth, or a Bearer token in an Authorization header
• The request body is flat (not deeply nested JSON)
• You need to receive inbound webhook payloads as a trigger (Webhooks by Zapier is the only option for Catch Hook triggers)
• You are already familiar with it and the configuration is straightforward for your use case

Use API by Zapier when:

• The API requires OAuth 2.0 or a more complex authentication flow
• The request body needs to be a properly structured nested JSON object
• You want a guided setup experience that validates configuration before saving
• You are building a Zap that others will maintain and want the configuration to be more readable

When to Use Code by Zapier Instead

Both Webhooks by Zapier and API by Zapier have limits: they handle a single API request per step and cannot handle pagination, conditional retry logic, or API responses that require transformation before use. When you need to make multiple API calls in sequence, paginate through API results, handle rate limiting with retry logic, or apply complex transformation to a response, Code by Zapier (JavaScript or Python) gives you full control. Code steps can use the built-in fetch function for HTTP requests and handle any response structure programmatically. See JavaScript libraries available in Zapier Code steps and Python libraries available in Zapier Code steps for what is available in each environment.

The right tool for API calls in Zapier depends on the complexity of the request. For a straightforward API call with a static endpoint and simple auth, Webhooks by Zapier is the fastest path. For anything requiring complex JSON bodies, OAuth, or conditional response handling, step up to API by Zapier or Code by Zapier.

Connecting Apps Without a Zapier Connector

Any app with a REST API and documentation can be connected to Zapier using Webhooks by Zapier or API by Zapier — no native Zapier connector required. This covers a large portion of modern SaaS products that have not yet published a Zapier integration. The main limitation is that outbound API calls (actions) are straightforward, but inbound triggers (something happening in the external app that starts a Zap) require the external app to support outbound webhooks — sending an HTTP request to Zapier's Catch Hook URL when an event occurs. For apps that do not support outbound webhooks, see Zapier missing trigger or action workarounds for alternative approaches. For help designing a Zap that calls a specific API, talk to Automation Ace.