Certificate decoder
Local
Paste PEM, DER, CSR or PKCS#7: subject, SANs, key, signature, extensions, validity and fingerprints, decoded in your browser.
HTTP and TLS
Redirect chains, security headers, TLS configuration and certificate handling.
7 tools, 3 of them local. 1 available, 6 planned.
Available
Planned
HTTP check
RemotePlanned
Redirect chain with status and location per hop, final headers, timings, HTTP version, compression and cookie flags.
Security headers
RemotePlanned
Grade and per-test findings from the MDN HTTP Observatory engine, with plain-language fixes and server snippets.
TLS quick check
RemotePlanned
Certificate, chain, expiry, protocols, key size and common misconfigurations in a few seconds.
TLS full scan
QueuedPlanned
A complete testssl.sh run on an isolated scan host: protocols, ciphers, vulnerabilities, grade and downloadable evidence, with live progress.
Certificate converter
LocalPlanned
PEM, DER, PKCS#7 and PKCS#12 conversions without the key leaving your browser.
CSR generator
LocalPlanned
Generate a key and certificate signing request locally, with the equivalent OpenSSL config shown.