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Belief index levels, Belief Volatility series, and the point-in-time record reach you through three channels. The data and the terms are the same in all three. What differs is what is doing the reading.

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One account, one key

A single account at beliefsystems.xyz/data issues one credential – a belief_live_ key – and that key opens all three channels. The API authenticates with it, an MCP client sends it as an Authorization header, and snapshot files accept it directly or accept a signed-in browser session instead. Registration is free and takes about a minute: work email, no password, a magic link. Each account holds up to three active keys, rotates and revokes them from the portal, and sees its own usage there.

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What the channels do not carry

Constituent compositions, the per-market panel, raw NAV, and sub-hourly granularity are not on the API or MCP. Data boundaries states each line and where the rest lives.

Data API quickstart

Base URL, authentication, and a first call in three steps.

MCP server

Client configuration, the tool reference, and scope.

Snapshot downloads

What each bundle contains, how to fetch it, and how to cite it.

Limits and errors

Rate limits, headers, error codes, and the history window.

Data boundaries

What each lane carries, and how /v1 changes over time.

Index Services

Production rights, redistribution, and full-fidelity data.