THIRI is to music theory what cURL is to HTTP — the layer so reliable that developers stop thinking about it and just build.

···

Every music AI app eventually gets a chord wrong and nobody on the team can hear it — THIRI is the engine that guarantees they never ship that moment.

···

It lets any AI agent comp like a jazz musician — correct voicings, correct spellings, correct reharmonizations — without needing a musician on the engineering team.

···

Stable Audio built the model, but they still need something to tell the model what Db7 actually is — that's THIRI.

···

Every music AI company is hand-rolling chord logic in a utils file somewhere — T.H.I.R.I. replaces that file with four endpoints and an MCP server that's already been tested against real charts in real keys.

POST /v1/resolve { "chord": "Cm7" } { "notes": ["C","Eb","G","Bb"], "midi": [60,63,67,70], "scales": [{"name":"Dorian","role":"primary"}] }

For Developers

Four REST endpoints. Bearer auth. Live at api.thiri.ai. Free tier, 30 req/min. Parse any chord, resolve to notes and MIDI, generate voicings, reharmonize progressions.

See the API

{ "mcpServers": { "thiri": { "url": "https://mcp.thiri.ai" } } }

For Agent Builders

MCP server live. Connect Claude, Cursor, or any MCP-compatible client to the harmony engine in one config block. Same auth, same endpoints, zero HTTP plumbing.

MCP Quickstart