X-WS-RateLimit-Remaining

Monitoring request consumption on IONOS CDN is handled through the X-WS-RateLimit-Remaining unofficial response header, which reports how many requests remain in the current rate limit window.

Table of Contents

Usage

IONOS CDN enforces per-IP rate limits on requests passing through its edge servers. The X-WS-RateLimit-Remaining header reports how many requests are left in the current window before the limit is reached. The value counts down with each request, giving API clients a way to monitor their consumption in real time. IONOS documentation names only the companion X-WS-RateLimit-Limit header, so the countdown behavior described here comes from observed responses.

The header appears alongside X-WS-RateLimit-Limit, which shows the total ceiling for the window. Reading both headers together reveals both the budget and the remaining balance. When the remaining value reaches zero, the CDN begins throttling or rejecting further requests until the window resets. Each edge server and each routing rule keeps its own per-IP bucket, so the counter may differ between edge servers.

This header follows the same pattern as the widely adopted X-RateLimit-Remaining, scoped to the IONOS CDN platform with the WS- prefix.

Values

Numeric countdown

The value is a non-negative integer decrementing with each request. The counter starts near the limit ceiling and counts down toward zero as requests consume the available budget. Observed values run from 978 to 999 against the 1000 limit.

Example

A response early in the current second shows most of the budget intact. The client has made seven requests against the observed limit of 1000.

X-WS-RateLimit-Remaining: 993

Both headers typically appear together, showing the full picture of the client's current rate limit status.

X-WS-RateLimit-Limit: 1000
X-WS-RateLimit-Remaining: 989

A busier moment shows a lower remaining count. The client is still within its budget.

X-WS-RateLimit-Remaining: 251

See also

Last updated: August 17, 2026