Nexus Mods setup

cpmm installs and updates mods through the Nexus Mods API.

Your API key

cpmm isn’t registered with Nexus Mods yet, so for now it uses a personal API key. Nexus allows personal keys for personal use and testing. Registration, and with it Single Sign-On, is planned before a wider release.

1. Sign in at nexusmods.com and open your account’s API key page.
2. Copy your personal API key.
3. Paste it into cpmm’s setup flow, or run:

cpmm nexus-key <KEY>       # validate and save
cpmm nexus-key --check
cpmm nexus-key --remove

The key is stored at ~/.config/nexusmods/apikey with owner-only permissions.

What cpmm sends, and when

• Your key stays on your machine. It is sent only to api.nexusmods.com. cpmm has no server of its own.
• Only what you ask for. cpmm makes requests when you run a command or press a button that needs Nexus data. Nothing polls in the background, and launching the game makes no requests.
• It identifies itself. Every request carries Application-Name: cpmm and the cpmm version.
• It respects rate limits. Metadata is cached for an hour, requirements for 15 minutes, and file manifests indefinitely. After a 429 response, cpmm waits for the reset time Nexus gives rather than retrying.
• No scraping or rehosting. Downloads come from links Nexus issues to your own account.

Premium and free accounts

Installing directly from the API (cpmm install <id>, updates, Collections) needs a Premium account. With a free account, use the Mod Manager Download button on a mod’s page, which hands cpmm an nxm:// link.

Mod Manager Download links

To make cpmm open nxm:// links:

cpmm register-handler            # make cpmm the default
cpmm register-handler --check    # which app handles nxm:// now
cpmm register-handler --unregister

cpmm installs the linked file along with its requirements and logs to ~/.local/share/cpmm/nxm.log. The handler is a plain desktop file association, so it also works in Steam’s Game Mode. Steam’s own browser refuses these links; see Steam Deck for alternatives.

Collections

cpmm collection show <slug or URL>      # contents, and what you already have
cpmm collection install <slug or URL>   # into a new profile named after it

cpmm installs the curator’s exact file versions in order, applies their FOMOD choices, turns their “load after” rules into cpmm rules and sorts. Use --into-current to merge into your active profile and --optional to include optional mods. If a large collection hits the API’s hourly limit, run the same command again to continue.