A practical field guide from Automation Ace.
The short answer
APIs can change data, read any data on demand, search, backfill history, and confirm success; webhooks can do none of that. A webhook is a one-way notification that something happened. An API is a two-way conversation where your automation asks questions and gives instructions. That is why nearly every automation that starts with a webhook still makes API calls.
This is one half of a pair; the other half is what webhooks can do that APIs can't. For the full decision guide, see API vs webhook: when to use each.
1. Create, update, and delete data
A webhook only reports that something happened. To do anything in another system, such as creating a contact, updating a deal stage, or deleting a duplicate, you call its API. Every Zapier action step is an API call under the hood.
2. Read any data, any time
An API lets your automation ask for exactly what it needs when it needs it: the current status of an order, a customer's full history, or today's open invoices. A webhook only delivers what the sender chose to include at the moment of the event.
3. Search, filter, and look things up
Finding the contact with a given email, listing records created this week, or checking whether an ID already exists all require API queries. This is how automations avoid duplicate records.
4. Fetch complete, current data after a thin event
Many webhooks send only an ID and an event type, or a snapshot that may already be stale. An API call re-fetches the full, current record so you act on the truth, not a summary.
5. Work with apps that do not offer webhooks
Plenty of systems, especially older or internal ones, expose an API but no webhooks. Polling the API is the only way to detect changes; see push vs pull automation.
6. Backfill history and reconcile missed events
Webhooks only cover events from the moment you subscribe, and a missed delivery may be gone for good. APIs let you pull historical records and run nightly reconciliation to catch gaps. See how to reprocess records safely.
7. Control timing, batching, and pace
With an API, your automation decides when to call and how much to request, so you can batch, schedule off-peak, and respect rate limits. With webhooks, the sender decides when data arrives.
8. Get an immediate response and confirm success
An API request returns a status code and body right away, so you know whether the action worked and can branch on errors. See the Zapier error handling playbook.
9. Manage configuration, including the webhooks themselves
APIs often let you create webhook subscriptions, manage users, change settings, and pull reports: the administrative side a webhook can never touch.
Using APIs in Zapier
- Native integrations are pre-built API calls. Start there.
- API by Zapier makes authenticated requests to any endpoint and can poll for new items. See API by Zapier vs Webhooks by Zapier.
- Webhooks by Zapier actions send simple GET, POST, and PUT requests. See GET requests in Code steps for more control.
- Code by Zapier handles complex requests, pagination, and parsing. See code automation.
The trade-offs
APIs require credentials that must be protected and renewed (see API credential terms and 401 errors), they are subject to rate limits, and when used for polling they add delay and task usage. The practical answer is to let webhooks tell you when, and APIs tell you what and do the work. For API-heavy projects, see API integration for non-technical teams.
Frequently asked questions
What can an API do that a webhook cannot?
An API can create, update, and delete data, read any available data on demand, search and filter records, backfill history, and return an immediate success or error response. A webhook can only notify you that an event happened.
Can a webhook update data in another app?
No. A webhook only delivers a notification. To change data in another app, your automation must call that app's API, which is what every Zapier action step does.
Why call an API after receiving a webhook?
Webhook payloads are often partial or stale. Calling the API fetches the complete, current record and lets you look up related data before acting.
How do I call an API in Zapier?
Use a native integration first. For endpoints without one, use API by Zapier for authenticated requests, Webhooks by Zapier actions for simple requests, or Code by Zapier for complex logic.
Disclaimer: Zapier features, plan availability, and settings can change. Confirm current details in Zapier's help documentation and the API documentation for the apps you connect before relying on a specific setting. This article may include links to apps, products, or services; some links may be affiliate links, which means Automation Ace may earn a commission at no extra cost to you.