Self-Signed Certificate Generator
Generate a self-signed TLS certificate and RSA private key with optional SAN DNS names for local development.
About this tool
Create a self-signed X.509 certificate and RSA private key for local HTTPS, staging labs, or internal services. Add a common name and extra Subject Alternative Names, then download PEM files — keys never leave your browser.
What you get
- RSA 2048 or 4096 bit key pair generation
- Self-signed X.509 certificate PEM with SHA-256 signature
- Subject Alternative Names from one DNS name per line
- Configurable validity period (1–825 days)
- Download cert.pem and key.pem separately
- On-screen PEM preview for certificate and private key
How to use
Enter the hostname (CN), optional extra DNS names, validity days, and key size. Generate, then download cert.pem and key.pem. Trust locally only — browsers warn on public sites.
Related searches
- self signed certificate generator
- openssl alternative
FAQ
How to generate a self-signed SSL certificate online?
Enter the hostname, optional SAN DNS names, validity days, and key size—then download cert.pem and key.pem.
What is a self-signed certificate used for?
Local development, staging labs, and internal services where you control trust stores and do not need a public CA chain.
How to add SAN names to a certificate?
List additional DNS names in the SAN field so browsers accept the cert when accessing those hostnames.
Why do browsers warn on self-signed certs?
Public CAs did not vouch for the identity, so clients cannot establish trust automatically—expected for dev, not for public production sites.
How to create a self-signed cert for localhost HTTPS development?
Set CN to localhost, add localhost and 127.0.0.1 as SAN entries, download cert and key, then import the cert into your OS or browser trust store.
By using this tool you agree to our Terms of Use and Privacy Policy. Results are provided as-is without warranty.