Data API

Base URL: https://api.beliefsystems.xyz Authentication: Authorization: Bearer belief_live_…

Quickstart

Get a key

Create an account and mint a key in the portal. Free, work email, about a minute. The secret is shown once.

Make a request

export BELIEF_API_KEY="belief_live_…"

curl -s https://api.beliefsystems.xyz/v1/indices/CONFLICT/latest \
  -H "Authorization: Bearer $BELIEF_API_KEY"

import os
import requests

resp = requests.get(
    "https://api.beliefsystems.xyz/v1/indices/CONFLICT/latest",
    headers={"Authorization": f"Bearer {os.environ['BELIEF_API_KEY']}"},
    timeout=10,
)
resp.raise_for_status()

latest = resp.json()["data"]
print(latest["ticker"], latest["indexLevel"], latest["computedAt"])

const res = await fetch("https://api.beliefsystems.xyz/v1/indices/CONFLICT/latest", {
  headers: { Authorization: `Bearer ${process.env.BELIEF_API_KEY}` },
});
if (!res.ok) throw new Error(`Belief Systems API ${res.status}`);

const { data } = await res.json();
console.log(data.ticker, data.indexLevel, data.computedAt);

X-API-Key is accepted for the same secret. Authorization: Bearer is the canonical form and the one every example here uses.

Read the envelope

Every successful response is { data, meta }. data is the payload; meta carries the attribution line, the license and terms URLs, and the moment the response was generated. History endpoints add the effective window to meta.

{
  "data": {
    "ticker": "CONFLICT",
    "name": "Belief Global Conflict Risk Escalation Expectations Index",
    "computedAt": "2026-08-29T23:05:31.969917Z",
    "indexLevel": "35.47662726",
    "baseIndexLevel": "100.00000000",
    "stale": false,
    "publicStatus": "active",
    "maturityType": "PERPETUAL",
    "compositionVersion": "24ecfc71d2ddb86c",
    "methodologyVersion": "midprice-v1",
    "inceptionAt": "2026-04-24T13:38:30.565565Z",
    "seriesPartiallyResolved": true,
    "seriesFullyResolved": false,
    "resolvedAt": null,
    "ceasedAt": null,
    "dataQuality": {
      "freshMarketsCount": 24,
      "staleMarketsCount": 0,
      "totalMarketsCount": 24,
      "freshDataPct": 100.0
    }
  },
  "meta": {
    "attribution": "Source: Belief Systems (beliefsystems.xyz)",
    "license": "https://beliefsystems.xyz/license",
    "termsUrl": "https://beliefsystems.xyz/terms",
    "generatedAt": "2026-08-29T23:07:04.118204Z"
  }
}

Levels are decimal strings, not JSON numbers – "35.47662726" rather than 35.47662726. They are exact as published, so parse them with a decimal type wherever the arithmetic has to round-trip. Timestamps are UTC with microsecond precision. Every index carries baseIndexLevel 100 at inception, which is what makes a level readable on its own: in the response above, CONFLICT at 35.48 is down 64.5% from its inception base.

Source: Belief Systems (beliefsystems.xyz) belongs on anything you publish from this data. It travels in meta.attribution on every response.

/v1 answers cross-origin preflights only for Belief Systems’ own origins, so browser JavaScript on your domain will fail. Treat it as server-to-server: call it from your backend, which is also where the key belongs – a key shipped to a browser is a published key. Non-production environments allow localhost, so a prototype that works against staging will not work in production.

There is no test mode. The API is read-only, so a live key is safe to use in development.

Endpoints

Endpoint	Returns
`GET /v1`	Service index: every endpoint, the free-tier limits, and a `key` block with your own limits and remaining quota
`GET /v1/indices`	The index catalog – ticker, name, publication status, last computation, staleness
`GET /v1/indices/{ticker}/latest`	Latest level, undelayed, with data-quality counts
`GET /v1/indices/{ticker}/history`	Level history. `start`, `end`, and `interval` (`1h` or `1d`) are all optional
`GET /v1/indices/{ticker}/reconstitutions`	Completed composition changes, newest first
`GET /v1/volatility`	The Belief Volatility catalog
`GET /v1/volatility/{ticker}/latest`	Latest computed tick and latest published value
`GET /v1/volatility/{ticker}/history`	Belief Volatility history, newest first
`GET /v1/downloads`	Where the full-depth snapshot bundles live

Each endpoint’s parameters, with a try-it panel, are in the API Reference tab. Tickers are case-insensitive; GET /v1/indices is the catalog.

The volatility endpoints return the envelope of the published /volatility surface verbatim – series, publicationState, tick, published inside data – rather than the flatter shape the index endpoints use. The website, the MCP tools, and /v1 all read the same structure, so a Belief Volatility value quoted from one channel always matches the other two. Belief Volatility methodology defines each field.

Limits and errors

Rate limits, the header set, error codes, and the 90-day window.

Data boundaries

What the API serves, where the rest lives, and how /v1 changes.

MCP server

The same data as tools, on the same key.

Getting Started

Understanding Indices

Belief Volatility

Transparency

Data Access

Risk & Legal

Reference

Quickstart

Endpoints

Next

Limits and errors

Data boundaries

MCP server

​Quickstart

​Endpoints

​Next

Limits and errors

Data boundaries

MCP server

Quickstart

Endpoints

Next