REST API quickstart

Base URL

HTTPS only. All endpoints are relative to this base.

Your first call

Apple's revenue for its last four quarters, from its SEC filings. Send your key in the X-API-Key header:

curl "https://api.metricduck.com/api/v1/data/metrics?tickers=AAPL&metrics=revenues&period=quarterly&years=1" \
  -H "X-API-Key: fda_your_api_key"

The response is keyed by ticker: data.AAPL.metrics.revenues.values holds one row per quarter (period, period_end, value). This call works on a free key. It counts as one tool call and costs 4 credits (1 ticker × 1 metric × 4 quarters).

Pro: API access to the pre-formatted statement routes (income-statement, balance-sheet, cash-flow and ratios) needs a Pro plan. A free key gets 403; on Free, use /data/metrics.

Create an account (no card) and your key is ready on the next screen. The free tier is 500 tool calls/day (resets 00:00 UTC) — the same quota whether you call the REST API directly or connect an agent over MCP.

Test it in your browser

Fastest sanity check — paste the key into api_key and open the URL:

https://api.metricduck.com/api/v1/data/metrics?tickers=AAPL&metrics=revenues&period=quarterly&years=1&api_key=fda_your_api_key

In code, send the key in the X-API-Key header (above). The api_key query param is for quick browser tests only. Authorization: Bearer is for web sessions, not API keys: the REST API doesn't recognize a key sent that way. Never ship a key in client-side code.