Webhook vs. API: Differences, use cases, and when to use each

Imagine two different needs in your system. When a payment clears, your application has to respond immediately and in the right way. But for generating a daily report, you just need a list of yesterday’s transactions. Both workflows involve data exchange, but they rely on different methods for getting it. 

A webhook fits the first scenario because the payment system can send an update the moment a specified event occurs. An application programming interface (API) fits the second because your reporting pipeline can request information on its own schedule. One is event-driven, while the other is request-driven.

That difference shapes how you design an integration. This webhook vs. API comparison explains each approach: who initiates communication, how timing affects your choice, what you need to handle when delivery fails, and why some teams combine the two.

Difference between a webhook and an API

An API defines how one software interacts with another. With a request-response API, your application sends a request and receives a response. You can retrieve records, change settings, or start a job, depending on the available endpoints. Repeatedly checking for updates, known as polling, is just one use.

A webhook is an HTTP callback that a system sends to a configured URL when a selected event happens. Instead of your application repeatedly checking for updates, the sending system initiates the request the moment the event happens. Your receiving endpoint still returns an HTTP response to acknowledge delivery.

What is a webhook vs. an API?

The comparison below focuses on event callbacks versus on-demand, request-response API interactions. A webhook is technically an HTTP request that can be part of an API. The practical distinction comes from who initiates the workflow and why. Your application calls an API when it needs data or an action, while a webhook is sent automatically when an event happens and the sender needs to contact your application.

These patterns often work together. A webhook provides a record identifier, and then an API request retrieves additional fields or performs a follow-up action. The notification tells your application when to act, while the API provides the operation it needs.

Teams sometimes also compare webhooks vs. REST APIs. REST describes an architectural style used by many HTTP APIs. A REST API exposes resources for reading or updating, while a webhook communicates that a selected event occurred. Both may use HTTP and JSON, so the transport and payload format alone don’t distinguish them.

When to use a webhook vs. an API

Deciding when to use a webhook vs. an API call starts with the workflow trigger. Determine whether your system needs to react to a change or initiate a request independently, then define how quickly the next system needs the result. It also helps to check the source’s supported events and endpoints before designing around either pattern.

Use a webhook for event-driven updates

Choose a webhook when a specific event should kick off the next step in your workflow and the source system can send that event. Common examples include:

• Payment confirmation: A payment-completed event can notify your order service to evaluate an order for fulfillment. This event delivery avoids repeatedly checking every pending payment for a status change.
• Pipeline completion: A sync-completion event can notify your orchestrator that a pipeline run has ended. Your workflow can then inspect the outcome before starting dependent work rather than relying on a fixed waiting period.
• Account changes: An account-updated event can prompt your application to refresh its local record. This is useful when changes are irregular and frequent polling would mostly return unchanged information.

The choice between webhooks vs. API polling also affects what you need to operate. With webhooks, you need an endpoint that can accept notifications and handle the sender’s delivery rules. For example, Fivetran’s webhook documentation specifies retries for failed deliveries, so your handler should tolerate receiving an event more than once.

Design the handler to record an accepted event before acknowledging it, then process longer tasks separately. Where the sender supports signatures, verify them before trusting the payload. Also define how you’ll detect gaps if delivery stops, since receiving some notifications doesn’t establish that every expected event arrived. 

Use an API for on-demand or controlled interactions

Choose an API when your application needs to decide what to request and when. The available endpoints determine how much control you have:

• Retrieving historical records: Request transactions for a reconciliation period, including older records created before your integration existed. A queryable history endpoint can provide data that future event notifications alone can’t supply.
• Changing a configuration: Update a resource setting after an operator approves the change. The request carries the intended modification, and the response tells your application whether the service accepted it.
• Starting a job: Trigger a supported operation after your own prerequisites finish. This gives your orchestrator control over the request, although you may still need another mechanism to learn when the job completes.

The control comes with implementation work. Your integration must respect authentication requirements, rate limits, and pagination, and it must have a recovery path for failed requests. Fivetran’s API design pitfalls also highlight why consistent records and identifiers matter when you collect data across multiple requests.

Before retrying a write, determine whether the previous request could have succeeded despite a lost response. Use the service’s documented idempotency mechanism where available, or verify the resource’s current state before repeating an operation. A successful request acknowledgment may also mean work was accepted for processing, so review the endpoint’s completion semantics.

Use both when the workflow needs it

Suppose your billing system sends an invoice-paid webhook containing an invoice ID. Your application accepts the notification, then uses that ID to call the billing API and request the invoice’s line items before updating an internal record. In this setup, the webhook callback starts the workflow, and the API supplies the additional detail.

When you combine the two, record which events you’ve already processed so a retried notification doesn’t repeat the update. If the billing API supports querying payment history, you can reconcile periodically to identify missing records.

How Fivetran uses APIs and webhooks

Fivetran supports both APIs and webhooks, but each serves a different purpose. To understand how they fit together, separate the interface used to manage a pipeline from the mechanisms that move source data into your destination:

• Fivetran REST API: Programmatically control Fivetran by creating and managing supported resources, such as connections and destinations, or controlling supported pipeline operations. The REST API overview explains these management workflows. This is distinct from calling a source application’s API to extract business records.
• Fivetran application connectors: Many of Fivetran’s data pipelines, particularly for SaaS data sources, extract data through APIs.
• Fivetran webhooks: Receive notifications about supported Fivetran lifecycle events at your endpoint. These pipeline event notifications can inform alerts or orchestration. Inspect the outcome in the payload before treating the run as successful.
• Webhooks event connector: Send source events into Fivetran through the connector’s unique URL. The Webhooks connector documentation explains that Fivetran buffers incoming events and loads them during syncs. It captures events from setup onward, so plan separately for historical data, and don’t assume notification arrival means immediate destination availability.

For example, source events can enter through the Webhooks connector, while an outgoing Fivetran webhook notifies your orchestrator that a sync has ended. After checking the sync status and any other dependencies, your orchestrator can use a supported REST API operation to run a transformation. These are distinct steps with separate completion conditions.

As you expand that workflow, programmatic pipeline management can make configuration repeatable across supported resources. Choose the appropriate source connectivity method independently, then explore Fivetran’s extensibility capabilities to automate pipeline management and orchestration.

FAQ

Is a webhook the same as an API?

No, a webhook is an event-triggered callback, while an API defines an interface for software interactions. A webhook can be part of a service’s API offering, but its notification role differs from an application making an on-demand request.

Is a webhook faster than an API?

A webhook can detect a change sooner than periodic API polling because it doesn’t wait for the next scheduled check. Actual delivery and processing delays depend on the systems involved, so webhooks don’t guarantee faster completion for every workflow.

Can you use webhooks and APIs together?

Yes, you can use a webhook to start a workflow and an API to retrieve details or perform an action. Design the combined workflow to handle repeated notifications, failed requests, and any ordering requirements.

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