itch.io Publish (butler)

Get a build onto an itch.io page and keep it updated. The page is created in the browser; all uploads go through butler, itch.io's command-line tool, with one command you'll use forever: butler push. butler diffs against the previous build and uploads only what changed. Deep CI/CD and flag detail lives in references/butler-ci.md.

When to use

Use when creating/updating an itch.io project page, installing or logging in to butler, uploading a build with butler push, choosing channel names, versioning uploads, or shipping a jam/demo/release build to itch.io.
Triggers: butler push, butler login, channels, .itch.toml, "publish on itch", "upload to itch".

When not to use: publishing on Steam (use steam-publish); jam scope/planning (use game-jam — this skill is only the upload mechanics); building the game itself (engine skills).

Core workflow

Create the project page at itch.io/game/new. Set the Kind of project: keep Downloadable for native builds, or choose HTML for a browser-playable game (this is required for web builds — see Pitfalls). Set pricing/visibility (Draft until ready).
Install butler and log in. Download from itchio.itch.io/butler, add it to PATH, then butler login (opens a browser to authorize). Verify with butler version. For CI, use BUTLER_API_KEY instead — see the reference.
Prepare a portable build folder — the exact files a player runs, nothing extra. Push a folder (or a single .zip of that folder), not an installer and not a pre-compressed archive of archives (hurts patching; see Pitfalls).
Push to a channel: butler push <dir> <user>/<game>:<channel>. The channel name determines the platform tag (see Patterns). The first push uploads everything; later pushes to the same channel upload only the diff.
Set platform/HTML tags on the Edit game page if a channel wasn't auto-tagged correctly, then Save. For browser games also flip the page to HTML and tag the channel playable in browser.
Version your builds (optional but recommended): --userversion 1.2.0 or --userversion-file build.txt so you control the version string players and the update API see.
Update later by pushing to the same channel again. Use butler status <user>/<game> to see channels/builds and butler push-preview to see what a push would change before sending it.

Patterns

1. The one command you need — `butler push`

# butler push <directory-or-zip> <user>/<game>:<channel>
butler push ./build/windows leafy/my-game:windows
butler push ./build/mac     leafy/my-game:osx
butler push ./build/linux   leafy/my-game:linux
butler push ./web           leafy/my-game:html   # browser build (also set page Kind = HTML)

2. Channel naming controls the platform tag (kebab-case, lowercase)

Substring in channel name -> auto-applied tag:
  win / windows  -> Windows        linux -> Linux
  mac / osx      -> macOS          android -> Android
Multiple platforms in one channel are allowed: e.g. a Java jar:
  butler push ./jar leafy/my-game:win-linux-mac
Convention: lowercase words separated by dashes (windows-beta, osx-demo, soundtrack).
Tags are only the INITIAL guess — fix them anytime on the Edit game page (then Save).

3. Version, verify, and preview

butler version                              # print version; confirms install + PATH
butler login                                # authorize this machine (opens browser)

# Set an explicit version string instead of itch's auto-incrementing integer:
butler push ./build leafy/my-game:windows --userversion 1.2.0
butler push ./build leafy/my-game:windows --userversion-file build_number.txt

butler status leafy/my-game                 # list channels + latest builds/versions
butler push-preview ./build leafy/my-game:windows   # NEW/MODIFIED/DELETED/SAME, uploads nothing

4. First-time, hidden, and filtered pushes

# Hide a brand-new channel from the page until you're ready (NEW channels only):
butler push ./build leafy/my-game:windows-beta --hidden

# Exclude files from the upload without copying the folder (--ignore is repeatable):
butler push ./build leafy/my-game:windows --ignore '*.pdb' --ignore '*.dSYM'

# Preview exactly what would be sent, without sending it:
butler push ./build leafy/my-game:windows --dry-run

Pitfalls

Pushing an installer. itch.io patches portable builds; an installer (.exe/.msi) defeats patching and the itch app's auto-update, and may need admin rights players don't have. Push the extracted, runnable folder instead.
Pre-compressed builds. Pushing a heavily compressed archive (or an archive of archives) makes patches huge — a tiny change rewrites the whole compressed blob. Push uncompressed files; itch.io compresses on its side.
A folder containing only one .zip. butler auto-unzips it and pushes the contents (to avoid a "zip in a zip"). Pass --no-auto-unzip only if you truly want the zip uploaded as one opaque file.
HTML5 game shows as a download. Two switches are required: set the page Kind to HTML and tag the channel playable in browser on the Edit game page after the first push — neither happens automatically from the channel name.
--hidden on an existing channel errors. It only applies when the push creates a new channel. Unhide later from Edit game.
Channel typos make duplicate slots. windows and win-final are different channels and create separate downloads. Decide your channel names up front and reuse them.
30 GB cap. itch.io rejects builds whose total uncompressed size exceeds 30 GB.
Secrets in CI logs. A BUTLER_API_KEY printed in a public log is compromised — revoke it immediately on the API keys page. See the reference for safe CI usage.

References

For CI/CD (GitHub Actions/GitLab) with BUTLER_API_KEY, automated install via broth, the full flag list, and the update-check API, read references/butler-ci.md.
Primary docs: the butler manual — itch.io/docs/butler (installing, login, pushing).

Related skills

steam-publish — the same game on Steam via SteamPipe (often shipped alongside itch.io).
game-jam — most jams are hosted on itch.io; this skill handles the upload step.
prototype-fast — share an early prototype on a Draft/restricted itch page for playtesting.

itch-publish