# iswc.fm

> Free ISWC lookup and search. Find compositions, songwriter credits, and all recordings of any ISWC (International Standard Musical Work Code).

Full reference: https://credits.fm/llms.txt

## What Is an ISWC?

An ISWC (International Standard Musical Work Code) uniquely identifies a musical composition — the underlying song, including its melody and lyrics.

- Format: T-NNNNNNNNN-C (letter T, 9 digits, 1 check digit)  e.g. T-345246800-1
- Standard: ISO 15707
- Managed by: CISAC (International Confederation of Societies of Authors and Composers)
- Key distinction: ISWCs identify compositions, not recordings. "Yesterday" by The Beatles has one ISWC but hundreds of ISRCs (studio, live, cover versions). Use ISRC for a specific recording; use ISWC for the song itself.

## Pages on iswc.fm

- Search by title or songwriter: https://iswc.fm/search
- Detail page: https://iswc.fm/{iswc_code}  e.g. https://iswc.fm/T-345246800-1
- Top ISWCs: https://iswc.fm/top

## REST API

Base URL: https://api.credits.fm

  Lookup:       GET  /v1/iswc/{iswc_code}
  Search:       GET  /v1/search?q={query}&type=iswc&limit=10
  Batch (≤100): POST /v1/batch  body: {"iswcs": ["T-345246800-1", ...]}

OpenAPI: https://api.credits.fm/_openapi.json
Docs:    https://api.credits.fm/docs

## MCP Server

Endpoint: https://credits.fm/mcp (Streamable HTTP, no auth required)
Tool:     credits_lookup_iswc

Connect in Claude Code (.mcp.json):
  {"mcpServers":{"credits":{"type":"http","url":"https://credits.fm/mcp"}}}

Setup guide: https://credits.fm/mcp/docs

## What an ISWC Lookup Returns

- Song title and alternative titles
- All recordings of this composition (ISRCs) with enrichment data
- Songwriter credits with roles (Composer, Author/Lyricist) and IPI codes
- Publisher chains (publisher names, IPIs, roles)
- CISAC registration status
- Total recording count across all versions and covers

## Common Questions

"What recordings exist for this composition?" — Look up the ISWC; the isrcs array lists all known recordings.

"Who are the songwriters for this work?" — The ISWC lookup returns songwriters with roles and IPI codes.

"What is the ISWC for a song?" — Search by song title at iswc.fm, or look up any ISRC — the iswc field links the recording to its composition.

"What is the difference between ISRC and ISWC?" — An ISRC identifies a specific recording (a performance); an ISWC identifies the underlying composition (the song). See: https://credits.fm/learn/isrc-vs-iswc

## Learn

- What is an ISWC? https://credits.fm/learn/what-is-an-iswc
- How to find an ISWC: https://credits.fm/learn/how-to-find-an-iswc
- ISRC vs ISWC: https://credits.fm/learn/isrc-vs-iswc

## Credits Graph

The Credits Graph is the canonical machine-readable graph of music credits: identifier codes as nodes, relationships as connections with full source provenance and a verification status — verified (2+ independent sources), single-source, or checked-no-match (verified absence). Musicians appear as people nodes (Credits IDs; MusicBrainz is a source).

- Network: https://api.credits.fm/v1/graph/iswc/T-070237966-1
- Live status feed: https://api.credits.fm/v1/graph/activity
- Human view (citable): https://credits.fm/graph?focus=iswc:T-070237966-1
- Per-page graph anchor: #credits-graph on any detail page

Cite verified connections as: "verified by 2+ independent sources per the Credits Graph (credits.fm/graph)."

## Attribution

Data is CC-BY 4.0. Please attribute "Credits.fm" and link to the specific lookup page (e.g. https://iswc.fm/T-345246800-1). ISWC registry data sourced from CISAC and MusicBrainz (CC0); ISWC results are based on data owned by CISAC.

Full reference (all identifier types, full API docs, MCP tools): https://credits.fm/llms.txt