OpenSource

Command line tool that lets you add an open source license to your project by running a simple command.

A single, dependency-free binary written in Go.

Supported Licenses

• MIT
• Apache 2
• BSD 3 Clause
• GPL 3
• ISC

Installation

Homebrew cask (macOS)

Install the signed and notarized binary for Apple Silicon or Intel Macs from the mohnish/opensource tap. Go is not required:

brew install --cask mohnish/opensource/opensource

Homebrew adds the tap automatically and trusts the OpenSource cask when you install it by its full name. No separate brew tap or brew trust step is needed. See Homebrew's tap trust documentation.

Verify the installation:

opensource --version

To upgrade later:

brew update
brew upgrade --cask mohnish/opensource/opensource

To uninstall:

brew uninstall --cask opensource

If you previously installed the Homebrew formula, remove it before installing the cask so both installations do not compete for the opensource command:

brew uninstall --formula opensource
brew install --cask mohnish/opensource/opensource

Your saved name and email in ~/.osrc are retained.

To remove the cask's trust after uninstalling:

brew untrust --cask mohnish/opensource/opensource

go install

go install github.com/mohnish/opensource@latest

Prebuilt binaries

Download an archive for your operating system and architecture from the releases page:

Operating system	Architectures	Archive
macOS	arm64 (Apple Silicon), amd64 (Intel)	.tar.gz
Linux	arm64, amd64	.tar.gz
Windows	arm64, amd64	.zip

Each release includes checksums.txt with SHA-256 checksums. Extract the archive and put opensource (or opensource.exe on Windows) in a directory on your PATH. The macOS binaries are signed and notarized.

Usage

Usage: opensource OPTIONS

Specific options:
    -s, --setup                      Setup user credentials in ~/.osrc file
    -l, --license LICENSE            LICENSE can be apache2, bsd, gpl3, isc, mit
    -a, --append README              Append LICENSE content to README file

Common options:
    -v, --version                    Print the version
    -h, --help                       Show this message

First, store your name and email (written to ~/.osrc):

opensource --setup

Then, from any project directory, generate a LICENSE file:

opensource --license mit

Optionally append a ## License section to a README:

opensource --license mit --append README.md

If you run --license before setting up credentials in an interactive terminal, you'll be prompted to enter them and the command continues automatically.

Development

Requires Go (see the go directive in go.mod for the minimum version).

Build the binary:

make build

Run the test suite:

make test

Format, vet, and see all shortcuts:

make fmt
make vet
make

Build an unsigned local release snapshot (no credentials or publishing) with GoReleaser:

make snapshot

Run the full release readiness check, including Go checks, all six archives, checksums, and a smoke test of the packaged binary on your machine:

make release-check

These targets use GoReleaser v2.18.2, matching CI. Go downloads it on first use; Python 3 is also required for release-check. To use an installed GoReleaser: make release-check GORELEASER=goreleaser.

Releasing

The Release workflow tests the code, builds release binaries, signs and notarizes the macOS binaries, publishes GitHub Release archives and checksums, then updates Casks/opensource.rb in mohnish/homebrew-opensource. It also publishes Linux and Windows binaries for arm64 and amd64. Binaries remain GitHub Release assets; neither repository stores them in Git history.

Maintainer setup

The public mohnish/homebrew-opensource repository is initialized on main. GoReleaser creates and updates the cask on each stable release; no manual cask or checksum edits are needed.

Configure these repository secrets in mohnish/opensource → Settings → Secrets and variables → Actions:

Secret	Value
HOMEBREW_TAP_TOKEN	Fine-grained GitHub PAT with Contents: Read and write for mohnish/homebrew-opensource.
MACOS_SIGN_P12	Base64-encoded Developer ID Application certificate and private key exported as a .p12.
MACOS_SIGN_PASSWORD	Password for the .p12 export.
MACOS_NOTARY_KEY	Base64-encoded App Store Connect team API key (.p8).
MACOS_NOTARY_KEY_ID	API key ID.
MACOS_NOTARY_ISSUER_ID	API issuer ID.

The tap token must grant access to mohnish/homebrew-opensource, and the Apple credentials must belong to the team issuing the Developer ID certificate. GITHUB_TOKEN is provided automatically by Actions for publishing this project's release.

Encode each credential file on macOS without line wrapping:

base64 -i DeveloperIDApplication.p12 | tr -d '\n' | pbcopy
base64 -i AuthKey_KEYID.p8 | tr -d '\n' | pbcopy

Run each command separately and save its clipboard value to the corresponding secret. See GoReleaser's signing and notarization documentation for credential setup.

Publish a release

Run the local checks before committing:

make release-check

Commit and push the release changes, including any updated release notes in History.md. Then create and push the next version tag (for example, v3.0.0):

git tag -a v3.0.0 -m "opensource v3.0.0"
git push origin v3.0.0

Both v3.0.0 and historical unprefixed tags such as 3.0.0 trigger the workflow; use one tag per version. Prerelease tags such as v3.0.0-rc.1 publish GitHub prereleases without updating the stable Homebrew cask.

For stable releases, a macOS job audits and installs the published cask, checks the binary's signature and version, and tests setup and license generation in a temporary directory. Wait for both jobs in the Release workflow run to succeed before announcing the release.

Local make release-check builds unsigned snapshots without publishing and cannot verify Apple credentials or tap permissions. The tagged workflow validates those integrations.

License

(The MIT License)

Copyright (c) 2026 Mohnish Thallavajhula <hi@iam.mt>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.