CSR / certificate decoder — read the details
Paste a PEM CSR or certificate and read its subject and public-key details. It decodes entirely in your browser (0 uploads, works offline) — the safe way to inspect a CSR tied to your private key.
How to use it
- Paste the PEM block (BEGIN…END).
- Read the subject distinguished name and key info.
- Copy or Download the details.
FAQ
How do I decode a CSR for free?
Paste the PEM and this page parses the ASN.1 structure to extract the subject fields — common name, organisation, country and more — and the public-key algorithm and size, on your device with no upload.
Is it safe to paste a CSR here?
Yes, and it is the reason this tool is client-side. A CSR is generated alongside a private key, so it should be decoded on your own device; here it is parsed in your browser and nothing is transmitted or stored, which you can verify by turning off your Wi-Fi.
What does it show?
The subject distinguished name (CN, O, OU, C, ST, L, email) and the public key's algorithm and size — for example RSA 2048-bit.
Does it verify the signature?
No. It decodes and displays the contents; it does not validate the CSR's signature or check it against a certificate authority.
Limits
Decodes the subject and key info; extensions, SANs and signature verification are not covered.
Related
The RSA key generator creates keypairs; the file checksum verifier checks file integrity.
Bookmark this page (Ctrl+D, or ⌘D on Mac) or install the app — it works offline the next time you need it.