Signal8 API

1. Get an API key

Create a free account and generate a key from the developer portal. Keys look like sk_live_* (or sk_test_* for test keys).

2. Authenticate

Send your key in the X-Api-Key header. The Authorization: Bearer sk_live_* form is also accepted.

curl "https://api.signal8.ai/api/v1/public/companies/AAPL" \
  -H "X-Api-Key: sk_live_YOUR_KEY"

3. Plans & rate limits

Plans scale rate limits and daily caps. Limits are enforced per API key — every response includes X-RateLimit-* and X-DailyLimit-* headers so you can track remaining quota. See full plan details on the pricing page.

4. MCP server (optional)

Use Signal8 directly from Claude, Cursor, and other MCP clients. The zero-install hosted Streamable HTTP endpoint is the primary path — point any client at it and authenticate with your API key via the Authorization: Bearer header:

{
  "mcpServers": {
    "signal8": {
      "type": "http",
      "url": "https://mcp.signal8.ai/mcp",
      "headers": {
        "Authorization": "Bearer sk_live_YOUR_KEY"
      }
    }
  }
}

Prefer to run it locally? Use npx @signal8ai/mcp with your key in the SIGNAL8_API_KEY env:

{
  "mcpServers": {
    "signal8": {
      "command": "npx",
      "args": ["-y", "@signal8ai/mcp"],
      "env": {
        "SIGNAL8_API_KEY": "sk_live_YOUR_KEY"
      }
    }
  }
}

For Claude Code, add the hosted server from your terminal (replace sk_live_YOUR_KEY with your key):

claude mcp add --transport http signal8 https://mcp.signal8.ai/mcp \
  --header "Authorization: Bearer sk_live_YOUR_KEY"

Claude's web custom connector (Settings → Connectors) requires OAuth, which the hosted server doesn't support yet — use the local config or Claude Code for now.

Failed requests return a non-2xx status with a JSON error envelope containing a stable machine-readable code and a human-readable message:

{
  "error": {
    "code": "NOT_FOUND",
    "message": "Company not found for ticker: ZZZZ"
  }
}

Common error codes

Tier errors (403)

Endpoints gated above your subscription tier return a flat 403 envelope with upgrade context:

{
  "success": false,
  "error": "This endpoint requires the Developer plan. Please upgrade to continue.",
  "code": "TIER_INSUFFICIENT",
  "requiredTier": "pro",
  "requiredTierName": "Developer",
  "currentTier": "free"
}

Handling 429s

When you hit the per-minute limit or daily cap, the response includes a Retry-After header (seconds). Wait at least that long before retrying, and use the X-RateLimit-Remaining and X-DailyLimit-Remaining headers to pace requests proactively. Retries should use exponential backoff.

Response envelope

Successful responses wrap the payload in a top-level data field:

{
  "data": {
    "ticker": "AAPL",
    "companyName": "Apple Inc"
  }
}

Pagination

List endpoints accept limit (results per page) and offset (rows to skip) query parameters. Paginated responses echo both values back alongside a total count where available.

Dates

All dates use ISO 8601: YYYY-MM-DD for calendar dates and UTC timestamps (2026-01-15T14:30:00Z) for instants.

Tickers

Ticker symbols are 1–5 letters, case-insensitive (normalized to uppercase). Exchange-prefixed forms like NASDAQ:NVDA are accepted and the prefix is stripped.