Use this check to inspect a browser, device, network, permission, media, or input capability directly in the current runtime before relying on it in another workflow.

Filename

Required string input.

Expected extension

Required string input.

Extract and compare a filename's final extension case-insensitively. An extension is a label only; this tool does not inspect file bytes or establish a safe MIME type. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Detected extension

The resulting detected extension returned as a string.

Matches expected

The resulting matches expected returned as a boolean.

• Results describe the current browser session and can change with permissions, privacy controls, hardware, drivers, network path, power state, or browser updates. Unsupported or withheld information is not proof that the underlying capability is absent.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Repeat the check in the browser and device that will actually be used, then confirm important behavior with the relevant operating-system or network diagnostics. Avoid granting permissions that are unnecessary for the test.

• Regular Expression Syntax Checker

  Check whether a JavaScript regular expression and its flags compile. It does not run the expression against user text or claim to detect catastrophic backtracking.

• Browser Info Checker

  Parse a user-agent probe into browser family, engine, operating system, and device type.

• What Is My IP Address?

  Show the public IPv4 and IPv6 addresses available to the current internet connection, reporting either family as unavailable when its probe cannot connect.