A .skill file is a ZIP archive containing everything a skill needs: the SKILL.md file plus its scripts and assets. Skill Packer turns GitHub skills into these portable files. You can copy it to another machine, archive it, or hand it to a teammate. Install it with npx skill-packer add my-skill.skill; no network access required. Since a .skill is a standard ZIP, any zip tool can open and manage it, which helps with manual archiving.

Packing needs internet: the server clones the skill's repository from GitHub to build the .skill file. Installing does not. Download .skill files on a machine with internet access and copy them to the offline machine (USB drive, internal network, any medium). Then install one of these ways:

• If the NPMJS is available: run npx skill-packer install my-skill.skill --global; it installs to ~/.agents/skills. Run it inside a project to install to ./.agents/skills.
• If not, use any zip tool: .skill is a standard ZIP. The one-click copy command on the download page, unzip my-skill.skill -d ~/.agents/skills/, works wherever unzip exists. GUI archive managers work too; no CLI needed.

npx skills installs directly from a live repository and needs network access to pull the current state. Skill Packer produces a standalone .skill file you can carry, archive, and install anywhere, including machines without internet. It is a packaging tool, the skill equivalent of a .deb or .gem package; npx skills is a live installer.

Skill Packer accepts repositories up to 100 MB. Each packing job times out after 5 minutes, and you can queue up to 10 jobs at a time. Downloaded files are tied to your browser session; finish downloads before closing the tab.

Skill Packer validates every skill before packing: it checks archives for path traversal, requires a root SKILL.md, and enforces size limits on actual decompressed bytes (zip-bomb protection). Skill Packer is open-source software, and its source code is available on GitHub.

Any tool that follows the SKILL.md convention: Claude Code, OpenCode, Cursor, and other agents that read skills from .agents/skills-style directories. The format follows the community standard from agentskills.io. The skill-packer CLI installs into 28+ agent directories automatically.