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scoi.io

Dev Tools

SSL Key Generator

Real RSA, ECDSA, and Ed25519 keys via Web Crypto, plus a self-signed certificate for local TLS. Nothing is uploaded.

Configuration

PKCS#8 private key · SPKI public key · X.509 v3 self-signed cert · RSA-4096 can take a few seconds

Private key

Public key

Self-signed certificate

Generate real keys in the browser

Create RSA, ECDSA, or Ed25519 keys plus a self-signed certificate with Web Crypto. Useful for local TLS, MQTT device identity, or a throwaway localhost cert. Private keys never leave the tab.

  1. 1. Choose an algorithm and size

    RSA 2048 is the usual local default. ECDSA and Ed25519 are smaller. Match what your server or device stack accepts.

  2. 2. Set the common name and lifetime

    localhost is fine for a dev cert. Days control the self-signed certificate expiry only.

  3. 3. Download or copy the PEM blocks

    You get a private key, public key, and certificate. Store the private key like any other secret.

Frequently asked questions

Are these keys uploaded?
No. Generation uses Web Crypto in your browser. We never see the PEM.
Can I use this for a public website?
Not as a replacement for a CA. The certificate is self-signed. Browsers will warn. Use Let’s Encrypt or your PKI for anything public.
Why generate keys here instead of OpenSSL?
Same math, fewer install steps on a locked-down laptop. OpenSSL is still the right tool when you need CSRs, intermediates, or automation.