Add the source content
Paste code or technical input, upload a supported plain text file, or load the working example. Check headers, delimiters, syntax, or line structure before processing.
Developer tools
CORS Header Analyzer
Result
The result will appear here after you run the tool.
The result will appear here after you run the tool.
The result will appear here after you run the tool.
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About this tool
About this tool
CORS Header Analyzer reviews Access-Control headers by detecting origin values, credentials combination, and wildcard usage inside your browser. It warns about unsafe wildcard with credentials and missing origin headers.
Review CORS response headers and highlight risky configurations. Use the full-width workspace to analyze content while reviewing syntax, encodings, protocol fields, and implementation details. The tool accepts plain text, provides focused options, and creates plain text output that you can inspect, copy, download, or save as a local draft.
Built for daily work
- Use CORS Header Analyzer for debugging, API development, configuration, testing, and deployment.
- Measure structure, values, or quality signals in a practical report before content is imported, published, committed, shared, or passed to another application.
- Check a small sample interactively before applying the same operation to a larger code or technical input workflow.
- Prepare cleaner plain text output for teammates, clients, documentation, testing, or downstream automation.
How to use this tool
How to use this tool
Configure the operation
Review the available processing controls. The selected controls determine how the CORS Header Analyzer interprets the source and builds the result.
Run the tool
Start the CORS Header Analyzer and review the result, visual preview, and technical report. Correct any reported issue and run the tool again when necessary.
Export or continue the workflow
Copy or download the plain text result, save a browser-local draft, or open a related tool for the next conversion, validation, or cleanup step.
Key features
Key features
Extract CORS-specific headers from pasted output
The tool reads a set of HTTP response headers and isolates the four CORS fields: Access-Control-Allow-Origin, Allow-Methods, Allow-Headers, and Allow-Credentials.
Risky configuration warnings
Flag potentially dangerous settings such as a wildcard origin with credentials enabled, or missing headers that could cause preflight failures.
Preflight compatibility check
Verify that the declared allowed methods and headers cover common browser preflight requests so you can predict whether a cross-origin call will succeed.
Plain-language explanations for each header
Each CORS header is accompanied by a short explanation of what it does and how it affects cross-origin requests from browsers.
Practical use cases
Practical use cases
- Use CORS Header Analyzer for debugging, API development, configuration, testing, and deployment.
- Measure structure, values, or quality signals in a practical report before content is imported, published, committed, shared, or passed to another application.
- Check a small sample interactively before applying the same operation to a larger code or technical input workflow.
- Prepare cleaner plain text output for teammates, clients, documentation, testing, or downstream automation.
- Keep repeat work in one browser workspace and continue directly into related formatting, validation, comparison, or conversion tools.
Private by default
For local tools, input is processed in your browser and is not sent to application analytics.
Data processing noticeTechnical details
Technical details
Input formatsplain text
Output formatsplain text
ProcessingLocal browser processing
Task controlsthe available processing controls
Maximum local file25 MB per supported file
Workspace featuresFocus mode, examples, copy, download, local drafts, and result reports
Limitations and important notes
Limitations and important notes
- Analysis depends on the supplied sample and may not represent every production case.
- Large or deeply structured input depends on available browser memory and may process more slowly on mobile devices.
- The tool implements practical browser-based processing and may not reproduce every feature of specialist desktop software or every vendor-specific extension.
- Keep the original source and review generated output before production, security-sensitive, financial, legal, or safety-critical use.
Frequently asked questions
Frequently asked questions
Review CORS response headers and highlight risky configurations. It is built to analyze content and present the result in a workspace that supports review, copying, downloading, and local drafts.
The current tool accepts plain text. Use the upload control for supported files or paste content directly into the editor.
The standard operation runs locally in your browser. Input and file contents are not sent to site analytics or stored on the server.
You can copy or download the processed plain text result. Available output depends on the task and selected options.
Analysis depends on the supplied sample and may not represent every production case. Always test important output in the application or workflow where it will be used.
Related guides and solutions
Related guides and solutions
How to debug CORS errors in the browser
A guide to diagnosing CORS errors: reading the browser message, checking response headers, and fixing the server side.
Learn moreHow to review HTTP security headers
A practical header-review checklist covering content restrictions, framing, MIME handling, transport, referrers, permissions, CORS, cookies, and caching.
Learn moreWhat local browser processing means for online tools
A transparent explanation of local tool processing, temporary browser memory, local storage, downloads, analytics boundaries, and cases that require remote services.
Learn moreRelated tools
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