Self-Signed Certificate Generator
Generate a private key and self-signed TLS certificate in your browser.
About this tool
Create a self-signed X.509 certificate and RSA private key for local development, staging labs, or internal services. Add a common name and optional SAN DNS names, then download PEM files.
What you get
- RSA key pair (2048 or 4096 bit)
- Self-signed certificate PEM with optional Subject Alternative Names
- Download certificate and private key separately
- Validity period you choose (up to 825 days)
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 will warn on public sites.
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.
By using this tool you agree to our Terms of Use and Privacy Policy. Results are provided as-is without warranty.