Crypto
Decode an X.509 certificate or CSR: subject, validity, SANs, key, and fingerprints.
Stamp a visual signature, text, date or check mark onto a PDF. Runs entirely in your browser — the file is never uploaded. This is a visual stamp, not a cryptographic digital signature.
Build and audit a Content-Security-Policy header, directive by directive.
Search a reference of common HTTP status codes.
Inspect a HAR (HTTP Archive) export from your browser's network tab — requests, status, size, timing and a waterfall.