`step-ca` is an online certificate authority for secure, automated certificate management for DevOps.
It's the server counterpart to the [`step` CLI tool](https://github.com/smallstep/cli) for working with certificates and keys.
Both projects are maintained by [Smallstep Labs](https://smallstep.com).
You can use `step-ca` to:
- Issue HTTPS server and client certificates that [work in browsers](https://smallstep.com/blog/step-v0-8-6-valid-HTTPS-certificates-for-dev-pre-prod.html) ([RFC5280](https://tools.ietf.org/html/rfc5280) and [CA/Browser Forum](https://cabforum.org/baseline-requirements-documents/) compliance)
- It's an [ACME server](https://smallstep.com/docs/step-ca/acme-basics/) that supports all [popular ACME challenge types](https://smallstep.com/docs/step-ca/acme-basics/#acme-challenge-types)
- [Single-use, short-lived JWK tokens](https://smallstep.com/docs/step-ca/provisioners#jwk) issued by your CD tool — Puppet, Chef, Ansible, Terraform, etc.
ACME is the protocol used by Let's Encrypt to automate the issuance of HTTPS certificates. It's _super easy_ to issue certificates to any ACMEv2 ([RFC8555](https://tools.ietf.org/html/rfc8555)) client.
- Supports the most popular [ACME challenge types](https://letsencrypt.org/docs/challenge-types/):
- For `http-01`, place a token at a well-known URL to prove that you control the web server
- For `dns-01`, add a `TXT` record to prove that you control the DNS record set
- For `tls-alpn-01`, respond to the challenge at the TLS layer ([as Caddy does](https://caddy.community/t/caddy-supports-the-acme-tls-alpn-challenge/4860)) to prove that you control the web server
- Delegate SSH authentication to `step-ca` by using [SSH certificates](https://smallstep.com/blog/use-ssh-certificates/) instead of public keys and `authorized_keys` files
- For user certificates, [connect SSH to your single sign-on provider](https://smallstep.com/blog/diy-single-sign-on-for-ssh/), to improve security with short-lived certificates and MFA (or other security policies) via any OAuth OIDC provider.
- For host certificates, improve security, [eliminate TOFU warnings](https://smallstep.com/blog/use-ssh-certificates/), and set up automated host certificate renewal.
- [Authenticate and obtain a certificate](https://smallstep.com/docs/step-cli/reference/ca/certificate/) using any provisioner supported by `step-ca`
- Securely [distribute root certificates](https://smallstep.com/docs/step-cli/reference/ca/root/) and [bootstrap](https://smallstep.com/docs/step-cli/reference/ca/bootstrap/) PKI relying parties
- [Renew](https://smallstep.com/docs/step-cli/reference/ca/renew/) and [revoke](https://smallstep.com/docs/step-cli/reference/ca/revoke/) certificates issued by `step-ca`
- [Install root certificates](https://smallstep.com/docs/step-cli/reference/certificate/install/) on your machine and browsers, so your CA is trusted
- [Inspect](https://smallstep.com/docs/step-cli/reference/certificate/inspect/) and [lint](https://smallstep.com/docs/step-cli/reference/certificate/lint/) certificates
* Tell us what you like and don't like about managing your PKI - we're eager to help solve problems in this space. [Join our Discord](https://u.step.sm/discord) or [GitHub Discussions](https://github.com/smallstep/certificates/discussions)
* Tell us about a feature you'd like to see! [Request a Feature](https://github.com/smallstep/certificates/issues/new?assignees=&labels=enhancement%2C+needs+triage&template=enhancement.md&title=)