Authentication

All API endpoints require an API key passed as the X-API-Key request header. Get one below — no card, no account, 100 free calls to try it with.

Already subscribed? Keys generated from the dashboard are linked to your account and pick up your plan's monthly allowance automatically.

# Curl
curl https://api.sentimentfx.org/v1/sentiment/BTC \
  -H "X-API-Key: sfx_your_api_key_here"

# Python
import requests
res = requests.get(
    "https://api.sentimentfx.org/v1/sentiment/BTC",
    headers={"X-API-Key": "sfx_your_api_key_here"}
)

# JavaScript
const res = await fetch(
    "https://api.sentimentfx.org/v1/sentiment/BTC",
    { headers: { "X-API-Key": "sfx_your_api_key_here" } }
)

Sentiment

{
  "ticker": "BTC",
  "limit": 25,
  "calls_used": 1,
  "data": [
    {
      "date": "2026-04-27T12:00:00",
      "title": "Bitcoin hits new yearly high amid ETF inflows",
      "source": "CoinDesk",
      "sentiment_score": 0.6821,
      "sentiment_label": "positive"
    }
  ]
}

Summary

{
  "ticker": "BTC",
  "days": 30,
  "calls_used": 30,
  "data": [
    {
      "date": "2026-04-27",
      "avg_sentiment": 0.2341,
      "article_count": 12,
      "label": "positive"
    }
  ]
}

Prices

{
  "ticker": "BTC",
  "days": 30,
  "calls_used": 30,
  "currency": "GBP",
  "data": [
    {
      "date": "2026-04-27T00:00:00",
      "close_price": 72841.50,
      "volume": 18294830293.0
    }
  ]
}

Correlation

{
  "ticker": "BTC",
  "calls_used": 1,
  "window_days": 180,
  "sample_size": 87,
  "primary_signal": {
    "type": "sentiment_shift_vs_next_day_return",
    "correlation": 0.241,
    "p_value": 0.0241,
    "ci_95": [0.033, 0.431],
    "strength": "weak",
    "direction": "positive (momentum)"
  },
  "interpretation": "Sentiment shifts show a weak positive (momentum) signal (r=0.241, p=0.0241, n=87)"
}

MCP — Claude, Cursor & other AI clients

SentimentFX also speaks the Model Context Protocol, so Claude Code, Claude.ai desktop, Cursor, Cline and any other MCP-compatible client can call the sentiment tools natively without you writing HTTP-plumbing code. Same X-API-Key, same billing, same rate limits — you just point the client at a URL.

Endpoint: https://api.sentimentfx.org/mcp

Auth: X-API-Key: sfx_... header (get a free key).

Tools exposed

Claude Code

Add to ~/.claude/settings.json (or your project's .claude/settings.json):

{
  "mcpServers": {
    "sentimentfx": {
      "type": "http",
      "url": "https://api.sentimentfx.org/mcp",
      "headers": { "X-API-Key": "sfx_your_key_here" }
    }
  }
}

Restart Claude Code and Claude will discover the six tools. Try "What's Bitcoin sentiment looking like this week?".

Cursor / Cline / Windsurf

Same JSON block under whatever MCP config panel the editor exposes — Cursor is Settings → MCP → Add new server, Cline lives in its side panel. The only field that ever changes is the URL/auth combo above.

Claude API (custom apps)

Use the Anthropic SDK's MCP client to attach the server to your messages.create call:

from anthropic import Anthropic
client = Anthropic()
resp = client.beta.messages.create(
    model="claude-opus-4-7",
    max_tokens=1024,
    mcp_servers=[{
        "type": "url",
        "url": "https://api.sentimentfx.org/mcp",
        "name": "sentimentfx",
        "authorization_token": "sfx_your_key_here",
    }],
    messages=[{"role": "user", "content": "Rank the top 5 tickers by 7-day sentiment shift."}],
)

Every MCP tool call bills the same meter as the equivalent /v1/* HTTP call — check usage on the dashboard's API Access panel.

Error Codes

Bulk dataset licence

The API is metered per call, which suits an application reading current sentiment. If you need the whole corpus at once — to backtest against, to train on, or to join to your own data — that's a licence rather than a subscription, delivered as CSV or JSONL.

Scores come from the same FinBERT pipeline behind the live API, so a backtest on the archive and a signal read from /v1/sentiment are directly comparable. Methodology is documented in full under Sentiment Scoring.