Privacy and local processing
Matching, replacements, unit tests, debugging, benchmarks, and file extraction run locally in your browser. Your test strings and files are not uploaded for these operations. Editor operations use local processing on both Free and Pro.
What runs on your device
- All supported regex engines run in your browser.
- Pattern explanations, syntax checks, and capture-group results use local processing.
- Unit tests compare your pattern with expected results locally.
- Substitution pipelines transform text locally.
- File loading reads text, binary data, PDFs, DOCX, ODT, and GZIP files on your device.
The browser downloads the application and engine resources first. Offline use needs these resources in its cache.
Features that use the service
| Action | Data sent to regex101 |
|---|---|
| Save or publish a workspace | The pattern, test strings, unit tests, and other saved fields. |
| API or MCP request | The fields supplied in that request. |
Workspace visibility controls access to saved content. Saving is separate from local matching.
MCP connects an AI client to saved workspaces and explanations. The AI client controls how it handles content from its conversation and tool requests.
Share only what you intend
Copy draft link puts editor content in a URL. Anyone who receives that URL can read its fields. Use a synthetic example for a public link, or choose a private saved workspace for account-only access.
The website privacy policy covers accounts and hosted services. Self-hosted Enterprise keeps saved workspaces in your own deployment.