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Rate limiting rules
Rate limiting rules allow you to define rate limits for requests matching an expression, and the action to perform when those rate limits are reached. Use rate limiting rules to prevent abuse of your websites and APIs — for example, to protect a login endpoint from brute-force attacks or to cap how many API calls a single client can make in a given time window.
In the new security dashboard, rate limiting rules are one of the available types of security rules. Security rules perform security-related actions on incoming requests that match specified filters.
Some Enterprise customers can create rate limiting rulesets at the account level that they can deploy to multiple Enterprise zones.
Rule parameters
Like other rules evaluated by Cloudflare's Ruleset Engine, rate limiting rules have the following basic parameters:
- An expression that specifies the criteria you are matching traffic on using the Rules language.
- An action that specifies what to perform when there is a match for the rule and any additional conditions are met. In the case of rate limiting rules, the action occurs when the rate reaches the specified limit.
Besides these two parameters, rate limiting rules require the following additional parameters:
- Characteristics: The set of parameters that define how Cloudflare tracks the rate for this rule.
- Period: The period of time to consider (in seconds) when evaluating the rate.
- Requests per period: The number of requests over the period of time that will trigger the rate limiting rule.
- Duration (or mitigation timeout): Once the rate is reached, the rate limiting rule blocks further requests for the period of time defined in this field.
- Action behavior: By default, Cloudflare will apply the rule action for the configured duration (or mitigation timeout), regardless of the request rate during this period. Some Enterprise customers can configure the rule to throttle requests over the maximum rate, allowing incoming requests when the rate is lower than the configured limit.
Refer to Rate limiting parameters for more information on mandatory and optional parameters.
Refer to How Cloudflare determines the request rate to learn how Cloudflare uses the parameters above when determining the rate of incoming requests.
Interaction with other app security features
If you are using several app security features like custom rules, Managed Rules, and Super Bot Fight Mode, it is important to understand how these features interact and the order in which they execute. Refer to Security features interoperability for more information.
Important remarks
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Rate limiting rules are evaluated in order, and some actions like Block will stop the evaluation of other rules. For more details on actions and their behavior, refer to Actions.
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Rate limiting rules are not designed to allow a precise number of requests to reach your origin server. There may be a delay of up to a few seconds between detecting a request and updating rate counters. Due to this delay, excess requests could still reach the origin before Cloudflare enforces a mitigation action such as blocking or challenging. For more information on how counters work, including their per-data-center scope, refer to Request rate calculation.
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Applying rate limiting rules to verified bots might affect Search Engine Optimization (SEO). For more information, refer to Improve SEO.
Availability
| Feature | Free | Pro | Business | Enterprise with app security | Enterprise with Advanced Rate Limiting |
|---|---|---|---|---|---|
| Available fields in rule expression |
Path, Verified Bot | Host, URI, Path, Full URI, Query, Verified Bot | Host, URI, Path, Full URI, Query, Method, Source IP, User Agent, Verified Bot | General request fields, request header fields, Verified Bot, Bot Management fields1 | General request fields, request header fields, Verified Bot, Bot Management fields1, request body fields2 |
| Cache exclusion | No | No | Yes | Yes | Yes |
| Counting characteristics | IP | IP | IP, IP with NAT support | IP, IP with NAT support | IP, IP with NAT support, Query, Host, Headers, Cookie, ASN, Country, Path, JA3/JA4 Fingerprint1, JSON field value2, Body2, Form input value2, Custom |
| Custom counting expression | No | No | Yes | Yes | Yes |
| Available fields in counting expression |
N/A | N/A | All rule expression fields, Response code, Response headers | All rule expression fields, Response code, Response headers | All rule expression fields, Response code, Response headers |
| Counting model | Number of requests | Number of requests | Number of requests | Number of requests | Number of requests, complexity score |
| Rate limiting action behavior |
Perform action during mitigation period | Perform action during mitigation period | Perform action during mitigation period | Perform action during mitigation period, Throttle requests above rate with block action | Perform action during mitigation period, Throttle requests above rate with block action |
| Counting periods | 10 s | All supported values up to 1 min3 | All supported values up to 10 min3 | All supported values up to 65,535 s3 | All supported values up to 65,535 s3 |
| Mitigation timeout periods | 10 s | All supported values up to 1 h3 | All supported values up to 1 day3 | All supported values up to 1 day3 4 | All supported values up to 1 day3 4 |
| Number of rules | 1 | 2 | 5 | 1005 | 100 |
Footnotes
1: Only available to Enterprise customers who have purchased Bot Management.
2: Availability depends on your WAF plan.
3: List of supported counting/mitigation period values in seconds:
10, 15, 20, 30, 40, 45, 60 (1 min), 90, 120 (2 min), 180 (3 min), 240 (4 min), 300 (5 min), 480, 600 (10 min), 900, 1200 (20 min), 1800, 2400, 3600 (1 h), 65535, 86400 (1 day).
Not all values are available on all plans.
4: Enterprise customers can specify a custom mitigation timeout period via API.
5: Enterprise customers must have application security on their contract to get access to rate limiting rules. The number of rules depends on the exact contract terms.
Footnotes
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Only available to Enterprise customers who have purchased Bot Management. ↩ ↩2 ↩3
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Supported period values in seconds:
10, 15, 20, 30, 40, 45, 60 (1 min), 90, 120 (2 min), 180 (3 min), 240 (4 min), 300 (5 min), 480, 600 (10 min), 900, 1200 (20 min), 1800, 2400, 3600 (1 h), 65535, 86400 (1 day). ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 -
Enterprise customers can specify a custom mitigation timeout period via API. ↩ ↩2
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Enterprise customers must have application security on their contract to get access to rate limiting rules. The number of rules depends on the exact contract terms. ↩
Next steps
Refer to the following resources:
- Create a rate limiting rule in the dashboard for a zone
- Create a rate limiting rule via API for a zone
For Terraform examples, refer to Rate limiting rules configuration using Terraform.
Related resources
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Cloudflare Rate Limiting (previous version, no longer available): Documentation for the previous version of rate limiting rules (billed based on usage).