What Cloudflare Security Level Controls
If you are trying to figure out how to choose Cloudflare security level, start with what the setting actually changes.
Cloudflare security level determines how aggressively Cloudflare challenges visitors based on their IP reputation and recent behavior.
This matters because the wrong setting can either let too much suspicious traffic through or create friction for real users.
The best choice depends on your site’s risk profile, traffic sources, and tolerance for challenge pages.
Cloudflare Security Level Options Explained
Cloudflare offers several security levels in the dashboard, each designed for a different balance of protection and user experience.
These settings influence when Cloudflare shows a managed challenge or browser verification step.
- Essentially Off: Minimal challenge behavior.
Best only for low-risk use cases where friction must be avoided.
- Low: Challenges only the most suspicious visitors.
Useful for many stable websites with mostly known traffic.
- Medium: A balanced default for many businesses.
Cloudflare challenges more aggressively than Low.
- High: Stronger verification for visitors with poor reputations or suspicious activity.
- I’m Under Attack: The most aggressive option.
Designed for active attack scenarios, especially volumetric HTTP abuse or obvious bot traffic.
These labels sound simple, but the practical impact depends on your audience.
A B2B site, an ecommerce store, and a public API portal may each need a different setting.
How Cloudflare Decides Who Gets Challenged
Cloudflare does not challenge everyone equally.
It uses signals such as IP reputation, threat intelligence, browser behavior, and request patterns to estimate risk.
Common factors include:
- Known malicious IP ranges
- Abnormal request frequency
- Requests associated with scraping or credential stuffing
- Traffic from anonymizers or proxies with poor reputation
- Suspicious headers or incomplete browser fingerprints
Because of that, a higher security level does not automatically block all traffic.
It increases the likelihood that questionable visitors must prove they are legitimate.
How to Choose Cloudflare Security Level Based on Site Type
The right setting usually starts with the type of site you run.
Some websites can tolerate more challenge friction, while others depend on fast access for returning users.
Choose Lower Levels for Low-Risk, High-Trust Sites
If your website serves a small internal team, a private community, or a known customer base, Low is often enough.
It preserves usability while still filtering obvious threats.
Sites that often fit this profile include:
- Internal portals
- Small business brochure sites
- Membership sites with predictable traffic
- Documentation sites with minimal abuse history
Choose Medium for Most Public Websites
Medium is a strong starting point for many organizations.
It offers a better balance of security and convenience for content sites, service businesses, and standard ecommerce stores.
If you are unsure how to choose Cloudflare security level, Medium is often the most practical default because it helps reduce abuse without creating too many unnecessary challenges.
Choose High for Frequent Abuse or Sensitive Logins
High is appropriate when your site is repeatedly targeted or when you want a more defensive posture around login pages, admin areas, or high-value resources.
It is especially useful if you see bots probing forms or trying credential attacks.
Choose I’m Under Attack During Active Incidents
This setting is not meant for permanent use.
It is best when you are in the middle of a confirmed attack, such as a sudden flood of suspicious requests or a coordinated bot event.
Turn it off once traffic stabilizes and move back to a standard setting.
Factors to Evaluate Before You Change the Setting
The best way to choose a security level is to assess real conditions instead of guessing.
Review your logs, traffic sources, and error reports before making changes.
- Traffic quality: Are most visitors legitimate browsers, or do logs show bots and unusual user agents?
- Audience geography: Do you receive traffic from regions with higher proxy usage or reputational risk?
- User sensitivity: Would a challenge page frustrate customers, donors, or members at critical moments?
- Attack history: Have you seen scraping, brute force attempts, or denial-of-service activity?
- Authentication flow: Does your site rely on login-heavy workflows that must remain smooth?
If your site is marketing-focused and visitors mostly land on informational pages, a stricter level may be acceptable.
If users need instant access to pay, sign in, or complete forms, friction should be introduced carefully.
How to Test the Impact Safely
Before locking in a higher security level, test it under normal conditions.
Cloudflare analytics can show whether the setting is causing unwanted challenge rates or support complaints.
A practical testing approach looks like this:
- Change the level during a low-risk period.
- Monitor challenge counts, blocked requests, and conversion-related pages.
- Check whether search engine crawlers, payment providers, or monitoring tools are affected.
- Ask a few users from different locations to browse the site and report issues.
- Review logs for false positives, especially around login, checkout, or API endpoints.
Testing is especially important if your site serves older browsers, corporate networks, or users behind shared IP addresses.
These visitors can look suspicious even when they are legitimate.
When Security Level Is Not Enough
Cloudflare security level is only one control.
If you need targeted protection, other features may be more precise and less disruptive.
- WAF rules for blocking specific request patterns
- Managed Rules for common web threats
- Bot Management for advanced bot detection
- Rate limiting for login abuse or form spam
- Turnstile for challenge-free human verification on forms
- Access for securing internal apps and admin tools
These tools can solve issues that a global security level cannot.
For example, if only your login page is under attack, a WAF or rate limiting rule is often better than raising the whole site to High.
Common Mistakes to Avoid
Choosing the highest setting is not always the safest path.
Overly aggressive security can block real users, hurt SEO performance in edge cases, and create avoidable support tickets.
- Leaving I’m Under Attack on permanently: This can create ongoing friction and degrade user experience.
- Using High without monitoring: You may not notice false positives until conversions drop.
- Ignoring crawler access: Search engines and uptime tools may need special handling.
- Assuming all bots are bad: Some bots are useful, including search engine crawlers and monitoring services.
- Not testing after changes: Even small shifts can affect forms, logins, and embedded services.
A Simple Decision Framework
If you want a quick way to choose, use this framework.
It is not perfect, but it is effective for most site owners.
- Use Low if traffic is trusted, volume is modest, and friction must stay minimal.
- Use Medium if you want balanced, general-purpose protection for a public website.
- Use High if your site is frequently targeted or you need stronger verification.
- Use I’m Under Attack only during an active incident or emergency response.
For many websites, Medium is the best starting point, followed by incremental adjustments based on analytics.
If abuse increases, raise protection in steps rather than jumping straight to the most aggressive setting.
How to Revisit the Setting Over Time
Security settings should not be permanent assumptions.
Reassess them after site changes, marketing campaigns, seasonal spikes, or a security incident.
Consider reviewing your Cloudflare security level when you:
- Launch a new product or landing page
- Experience a sudden traffic surge
- Add a login or checkout flow
- See a rise in bot activity
- Change audiences or expand into new regions
In practice, how to choose Cloudflare security level comes down to ongoing observation.
The best setting is the one that blocks enough risk without interfering with the people you actually want to reach.