Throttling

Throttling is the deliberate reduction of the speed or number of requests, connections or data transfers allowed for a user, application or account, applied by a server, hosting provider or network to protect resources or enforce limits.

Why it matters

Hosts throttle to keep one customer from consuming shared CPU, disk or bandwidth. Cloud providers throttle burstable instances when their CPU credits run out, and APIs throttle clients that send too many requests. From your side the symptom is slowness or errors rather than a clean outage, which makes it easy to misdiagnose.

Throttling differs from a block: traffic still flows, only at a reduced rate, until you slow down or upgrade.

Example

An API allows 100 requests per minute. The 101st request in the window returns:

HTTP/1.1 429 Too Many Requests
Retry-After: 30

A well-behaved client waits 30 seconds and retries, ideally with exponential backoff.

Common mistakes

• Retrying instantly in a loop, which prolongs the throttling.
• Blaming the network when the real cause is an exhausted CPU credit balance or monthly transfer cap.
• Not reading the provider's limits before choosing a plan.

Related

• Rate limiting
• Latency
• Shared Hosting
• Auto Scaling

This page is general information written by our editorial team and updated when documentation changes. Servers and providers differ, so test changes safely first. See our editorial policy and disclaimer.