mkcert

This is a fork of https://github.com/filosottile/mkcert

mkcert is a simple tool for making locally-trusted development certificates. It requires no configuration.

$ mkcert -install
Created a new local CA 💥
The local CA is now installed in the system trust store! ⚡️
The local CA is now installed in the Firefox trust store (requires browser restart)! 🦊

$ mkcert example.com "*.example.com" example.test localhost 127.0.0.1 ::1

Created a new certificate valid for the following names 📜
 - "example.com"
 - "*.example.com"
 - "example.test"
 - "localhost"
 - "127.0.0.1"
 - "::1"

The certificate is at "./example.com+5.pem" and the key at "./example.com+5-key.pem" ✅

Using certificates from real certificate authorities (CAs) for development can be dangerous or impossible (for hosts like example.test, localhost or 127.0.0.1), but self-signed certificates cause trust errors. Managing your own CA is the best solution, but usually involves arcane commands, specialized knowledge and manual steps.

mkcert automatically creates and installs a local CA in the system root store, and generates locally-trusted certificates. mkcert does not automatically configure servers to use the certificates, though, that's up to you.

Installation

Warning: the rootCA-key.pem file that mkcert automatically generates gives complete power to intercept secure requests from your machine. Do not share it.

This fork is distributed as pre-built binaries attached to each GitHub release. They are statically linked (CGO disabled), so there are no runtime dependencies, and each one is published alongside a .sha256 checksum and a Sigstore build-provenance attestation you can verify.

Binaries are built for linux-amd64, linux-arm64, linux-arm, darwin-amd64, darwin-arm64, windows-amd64, and windows-arm64. Each asset is named mkcert-<version>-<os>-<arch>.

macOS and Linux

With the GitHub CLI you can grab the newest release for your platform in one step:

PLATFORM="linux-amd64" # or linux-arm64, linux-arm, darwin-amd64, darwin-arm64
gh release download --repo monetr/mkcert --pattern "mkcert-*-${PLATFORM}"
chmod +x mkcert-*-"${PLATFORM}"
sudo mv mkcert-*-"${PLATFORM}" /usr/local/bin/mkcert

Without it, download straight from the latest release (fill in the version shown there):

VERSION="v1.4.5" # the latest tag from the releases page
PLATFORM="linux-amd64"
curl -fsSL -o mkcert \
  "https://github.com/monetr/mkcert/releases/download/${VERSION}/mkcert-${VERSION}-${PLATFORM}"
chmod +x mkcert
sudo mv mkcert /usr/local/bin/mkcert

Windows

Download mkcert-<version>-windows-amd64.exe (or windows-arm64) from the latest release, or use the GitHub CLI:

gh release download --repo monetr/mkcert --pattern "mkcert-*-windows-amd64.exe"

Rename it to mkcert.exe and put it somewhere on your PATH. If you're running into permission problems try running mkcert as an Administrator.

Verifying a download

Every release binary ships with a matching .sha256 checksum and a build-provenance attestation, so you can confirm a download is intact and was actually built by this repo's release workflow:

# Checksum: download the .sha256 asset next to the binary, then
sha256sum -c mkcert-v1.4.5-linux-amd64.sha256

# Provenance, using the GitHub CLI:
gh attestation verify mkcert-v1.4.5-linux-amd64 --repo monetr/mkcert

Build from source

Building from source requires Go 1.18+.

git clone https://github.com/monetr/mkcert && cd mkcert
make build

make build produces an unversioned ./mkcert. To stamp the version the way the release workflow does:

go build -ldflags "-X main.Version=$(git describe --tags)"

Firefox support on Linux

mkcert installs the local CA into the Firefox (and Chromium) NSS trust store using certutil. If you use Firefox on Linux, install it first:

sudo apt install libnss3-tools
    -or-
sudo yum install nss-tools
    -or-
sudo pacman -S nss
    -or-
sudo zypper install mozilla-nss-tools

Supported root stores

mkcert supports the following root stores:

• macOS system store
• Windows system store
• Linux variants that provide either
  • update-ca-trust (Fedora, RHEL, CentOS) or
  • update-ca-certificates (Ubuntu, Debian, OpenSUSE, SLES) or
  • trust (Arch)
• Firefox (macOS and Linux only)
• Chrome and Chromium
• Java (when JAVA_HOME is set)

To only install the local root CA into a subset of them, you can set the TRUST_STORES environment variable to a comma-separated list. Options are: "system", "java" and "nss" (includes Firefox).

Advanced topics

Advanced options

	-cert-file FILE, -key-file FILE, -p12-file FILE
	    Customize the output paths.

	-client
	    Generate a certificate for client authentication.

	-ecdsa
	    Generate a certificate with an ECDSA key.

	-pkcs12
	    Generate a ".p12" PKCS #12 file, also know as a ".pfx" file,
	    containing certificate and key for legacy applications.

	-csr CSR
	    Generate a certificate based on the supplied CSR. Conflicts with
	    all other flags and arguments except -install and -cert-file.

Note: You must place these options before the domain names list.

Example

mkcert -key-file key.pem -cert-file cert.pem example.com *.example.com

S/MIME

mkcert automatically generates an S/MIME certificate if one of the supplied names is an email address.

mkcert filippo@example.com

Mobile devices

For the certificates to be trusted on mobile devices, you will have to install the root CA. It's the rootCA.pem file in the folder printed by mkcert -CAROOT.

On iOS, you can either use AirDrop, email the CA to yourself, or serve it from an HTTP server. After opening it, you need to install the profile in Settings > Profile Downloaded and then enable full trust in it.

For Android, you will have to install the CA and then enable user roots in the development build of your app. See this StackOverflow answer.

Using the root with Node.js

Node does not use the system root store, so it won't accept mkcert certificates automatically. Instead, you will have to set the NODE_EXTRA_CA_CERTS environment variable.

export NODE_EXTRA_CA_CERTS="$(mkcert -CAROOT)/rootCA.pem"

Changing the location of the CA files

The CA certificate and its key are stored in an application data folder in the user home. You usually don't have to worry about it, as installation is automated, but the location is printed by mkcert -CAROOT.

If you want to manage separate CAs, you can use the environment variable $CAROOT to set the folder where mkcert will place and look for the local CA files.

Installing the CA on other systems

Installing in the trust store does not require the CA key, so you can export the CA certificate and use mkcert to install it in other machines.

• Look for the rootCA.pem file in mkcert -CAROOT
• copy it to a different machine
• set $CAROOT to its directory
• run mkcert -install

Remember that mkcert is meant for development purposes, not production, so it should not be used on end users' machines, and that you should not export or share rootCA-key.pem.