musescore-fpx

MuseScore via fpx (no MCP)

musescore.com has no public API (the old one was shut down) and sits behind a Cloudflare managed challenge ("Just a moment…") that 403s any plain curl/Node request. fpx routes the request through the user's own signed-in browser tab (the Transporter extension), which has already cleared the challenge, so the same page loads that a browser would get. No MuseScore login is required for search/metadata — just a normal open tab.

This is the same data the musescore_search / musescore_get_score / musescore_download MCP tools return, reached with one CLI call instead of a running server.

One-time setup

npm install -g @fetchproxy/cli               # provides `fpx`
fpx profile add musescore --domain musescore.com
fpx pair -p musescore                        # prints a pair code → approve in Transporter

Requirements: the Transporter browser extension installed, with an open musescore.com tab (apex host — no www) that has cleared the Cloudflare challenge, and its Chrome Site access allowing musescore.com. Pairing persists — after the first approval every later fpx call reuses it.

Core call — and the JSON-store extraction it needs

Every page is a plain GET, HTML in, HTML out:

fpx get 'https://musescore.com/sheetmusic?text=zelda&recording_type=free-download' -p musescore \
  > /tmp/search.html

The fetched HTML has no result cards — MuseScore hydrates the DOM client-side. The real data is an HTML-entity-encoded JSON store embedded in the markup (MuseScore's analogue of a Next.js __NEXT_DATA__ blob). jq alone can't read it — decode the entities and bracket-match the array/object you want first. references/extract-store.js is a small, dependency-free Node script that does exactly that (mirrors src/store.ts's recoverJson/findArrayByKey/findEnclosingObject); pipe the saved HTML through it, then jq:

node references/extract-store.js scores < /tmp/search.html | jq '.[] | {id, title, composer_name}'

Ready-to-run URL patterns (search, score detail, static render assets) and their jq projections are in references/endpoints.md.

The one rule: search returns ids, detail needs both ids

A score's canonical path is /user//scores/ — search cards carry id (score id) and user.id (uploader id), so resolve those from a search hit before fetching the detail/download page:

node references/extract-store.js scores < /tmp/search.html \
  | jq -r '.[0] | "\(.user.id)\t\(.id)\t\(.title)"'
# 12345   67890   Zelda Theme (arr.)

Downloads: fpx can only RESOLVE the URL, never fetch the bytes

The score-detail store's type_download_list array carries the official download link (musescore.com/score/download/index?score_id=…&type=…&h=…). That endpoint is Cloudflare-walled AND 302-redirects cross-origin to a presigned S3 URL. A browser-tab fetch() (what fpx get/request does) hits the bot wall on that endpoint and, even if it didn't, can't read an opaque cross-origin redirect. The MCP works around this with a download bridge capability (chrome.downloads.download, which issues the request from the browser's own network stack) — fpx has no equivalent verb, so from the shell you can only resolve the URL, not save the file. Print it and open it yourself in the signed-in tab:

node references/extract-store.js type_download_list < /tmp/score.html \
  | jq -r '.[] | select(.type=="pdf") | .url'

Entitlement to check before trusting that link will actually download: is_free === true OR hasAccess === true (see references/endpoints.md).

Exit codes (fpx verbs)

• 0 — success.
• 2 — bridge unavailable: extension not connected or pairing pending → run fpx pair -p musescore, confirm a musescore.com tab is open.
• 3 — bot wall: the tab hasn't cleared Cloudflare → open/refresh a musescore.com tab and retry.
• 4 — upstream non-2xx from MuseScore.

Notes

• Anonymous reads only — search, score metadata, and download-URL resolution need no MuseScore account. Stay within musescore.com's terms; never automate a purchase.
• fpx health -p musescore shows bridge connection state when a call fails.
• The rendered page-1 SVG/PNG assets (musescore.com/static/musescore/scoredata/g//score_0.svg|png@0) are session + Referer-gated — they only work fetched via fpx (through the tab), never a plain curl. See references/endpoints.md.
• This project is developed and maintained by AI (Claude).