Inspect & Parse tools
Take an expression, a string, or a header apart and see what it means.
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Test a regular expression online
Test a JavaScript regular expression against sample text and see every match highlighted live.
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Validate JSON against a JSON Schema
Paste a JSON document and a JSON Schema to see every validation error with its instance path. Supports draft 2020-12 and draft-07, entirely in your browser.
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Parse a cron expression and see its next run times
Paste a 5-field cron expression to get a plain-English summary and the next 5 run times, in your browser.
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Parse a User-Agent string online
Paste a browser User-Agent string to see its browser, operating system, and device type, in your browser.
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Parse and view HTTP headers online
Paste raw HTTP request or response headers to see them parsed into a labeled table, in your browser.
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Build a curl command online
Build a shell-safe curl command from a method, URL, headers, and body, in your browser.
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Convert Unix file permissions
Convert between octal (e.g. 755) and symbolic (rwxr-xr-x) file permission notation, in your browser.
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Calculate a subnet from CIDR notation
Get the network address, broadcast address, subnet mask, and usable host range for any CIDR block, in your browser.
About Inspect & Parse tools
The regex tester shows matches and capture groups against sample text as you type, which turns a guessing game into an experiment. The cron parser prints the next run times for an expression — the reliable way to catch a schedule that reads like every fifteen minutes but is not. The User-Agent and HTTP header parsers break opaque strings into labelled fields.
The remainder solve arithmetic nobody should do in their head: the curl builder assembles a correct command with its flags and quoting, the permissions tool moves between 755 and the rwx form, and the CIDR calculator turns a prefix into its network address, broadcast address, and usable host range.