CORS Header Checker
Test a URL's CORS configuration. Shows Access-Control-Allow-Origin, methods, headers, credentials policy, and preflight behaviour. Identifies over-permissive wildcard configurations.
Data handling: The target URL is sent to allorigins.win, which fetches the page for this check.
About CORS Header Checker
CORS Header Checker provides a dedicated, focused workspace: Test a URL's CORS configuration. Shows Access-Control-Allow-Origin, methods, headers, credentials policy, and preflight behaviour. Identifies over-permissive wildcard configurations. Using it is a three-step job: 1) Open CORS Header Checker and review the inputs, units, and data-handling notice shown on its page, 2) Enter the information requested by this tool and adjust only the options that apply to your task, 3) Review the result and use the available copy, download, or reset controls. Processing depends on the specific operation. Any external lookup or service should be identified near the tool controls.
CORS Header Checker is a free, browser-based cors checker from ProfitTool. Test a URL's CORS configuration. Shows Access-Control-Allow-Origin, methods, headers, credentials policy, and preflight behaviour. Identifies over-permissive wildcard configurations. Review any usage notes shown on this page before relying on its availability. Review the tool's data-handling notice before entering sensitive information; some features store settings locally or contact external services.
If you came here from the Security Headers Checker, try SPF Record Checker to finish the job.
Data Handling
Data handling depends on this tool's implementation. Read the Data handling notice above the tool before entering sensitive information. Some features run locally; others contact named providers or ProfitTool services. Site analytics, advertising, and embedded resources may also make separate requests.
Industry Best Practices
- Read the field labels, units, and instructions before using CORS Header Checker.
- Keep a copy of important source material when the operation could change or transform it.
- Review the result before sharing or relying on it; check the page for available copy or download controls.
- Cross-check consequential results against an authoritative source; this tool does not replace professional advice.
- Review CORS Header Checker's data-handling notice before entering sensitive information.
Why this matters
Weak, reused credentials remain the leading cause of account takeover. Generating genuinely random secrets and understanding how strong they actually are is the highest-leverage security habit available to a non-specialist.
Common Mistakes to Avoid
Substituting characters and calling it strong
P@ssw0rd1 is on every cracking list. Randomness beats cleverness every time.
Storing generated secrets in notes apps
Use a real password manager with encryption at rest.
Reusing one strong password everywhere
One breach then exposes every account. Unique per site, always.
Already used our SPF Record Checker? HTTP Header Checker covers the other half of the workflow.
Technical Limitations & Boundary Conditions
- Results reflect the inputs and assumptions shown. Fees, taxes, rates, and personal circumstances can change the real-world outcome; verify important figures with the relevant provider or authority.
- Extreme values outside standard ranges may be constrained by device memory or numerical precision boundaries.
How to use CORS Header Checker
- 1Open CORS Header Checker and review the inputs, units, and data-handling notice shown on its page.
- 2Enter the information requested by this tool and adjust only the options that apply to your task.
- 3Review the result and use the available copy, download, or reset controls. Processing and storage behavior vary by tool.
Working alongside the HTTP Header Checker? Security Headers Checker handles the follow-up case.
Frequently Asked Questions
Is anything I enter into CORS Header Checker sent over the internet?›
Do not enter a live password, key, or token unless you have checked the tool's data-handling notice and verified its behavior.
Is my data safe when I use this cors checker?›
Data handling varies by tool. Read the notice above the workspace to see whether your input stays in the browser or is sent to a named provider or service. Avoid entering sensitive information unless you understand that tool's handling.
How strong should my output be?›
For anything valuable, aim for at least 16 characters with mixed classes, or a four-plus-word passphrase, and store it in a password manager.
How is CORS Header Checker different from other online cors checker tools?›
It does one job without pop-ups, forced sign-in or interstitials, and remembers your settings between visits so repeat work takes seconds.
Can I trust a browser-based cors checker?›
Read the Data handling notice above the tool to see whether inputs stay local or are sent to a provider.
Do I need to install anything to use CORS Header Checker?›
No installation, extension or account. Open the page and start — you can also add it to your home screen for one-tap access.
Should I reuse results across accounts?›
Never. Generate a fresh value per account so a single breach cannot cascade into your other logins.