API polling is a client-driven software pattern that repeatedly sends requests to an API endpoint to check for new data, events, or job status. The client controls the timing, unlike a webhook, where the server sends an update when an event occurs. It is simple and widely compatible, but the interval must balance freshness, rate limits, and unnecessary requests.
API polling
What is API polling?
API polling is a client-driven pattern in which software repeatedly sends requests to an API endpoint for new data, events, or status changes. In REST API polling, the client asks at set intervals instead of waiting for the server to send an update.
How API polling works
A backend can poll an API in a controlled loop for a limited time.
- Submit work, such as generating a report.
- Receive a job ID and a processing response.
- Request the job-status endpoint on a schedule.
- Handle processing, success, or failure states.
- Save the result and stop polling when the job ends.
Short polling vs long polling vs webhooks
The right choice depends on how quickly updates must arrive.
| Method | Response | Best fit |
|---|---|---|
| Short polling | Immediate, often empty | Simple status checks |
| Long polling | Held until data or timeout | Less frequent updates |
| Webhook | Server initiates delivery | Event-driven updates |
WebSockets can be better for continuous, two-way real-time communication.
Benefits of API polling
Polling is a practical option when status checks are enough.
- Works with many REST APIs.
- Uses familiar API requests.
- Lets the client control timing.
- Works when webhooks are unavailable.
Limitations and safe polling practices
Frequent polling can return empty responses, create stale updates, hit rate limits, and duplicate work.
- Choose an interval based on how often data changes.
- Use exponential backoff with jitter after failures.
- Set a deadline or maximum attempt count.
- Make result handling idempotent, so repeats are safe.
- Use conditional requests when supported.
- Protect calls with API authentication and follow the provider's documentation.
Building polling workflows with Emergent
Emergent can help build full-stack apps that call third-party APIs, store job IDs, retry safely, and show progress. See how to build an API-based workflow with Gmail. Build reliable API integrations with Emergent.
Frequently Asked Questions
Your Questions, Answered
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What does it mean to poll an API?
It means sending repeated requests to an API to check whether data or a status has changed.
What is polling in REST API?
It is a REST client repeatedly calling an endpoint, usually with HTTP GET, on a schedule.
What is webhook vs. polling?
Polling makes the client ask for updates. A webhook lets the server send an update when an event occurs.
Is polling or WebSocket better?
Polling suits occasional status checks. WebSockets suit low-latency, continuous two-way updates.
Can a backend poll an API on a loop?
Yes, but it should use delays, backoff, rate-limit handling, and a clear stopping condition.
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