How many ISINs can I look up in one API call?

The call

bash
curl -s --max-time 300 -X POST https://fundfactsapi.com/api/v1/funds \
  -H "Authorization: Bearer $FUNDFACTS_API_KEY" -H "Content-Type: application/json" \
  -d '{"isins":["IE00B4L5Y983","IE00B3RBWM25","LU1681043599"],"wait":true}'

json
{
  "results": [
    { "input": "IE00B4L5Y983", "isin": "IE00B4L5Y983", "status": "ok", "name": "iShares Core MSCI World UCITS ETF", "cached": true, "expiresAt": "…", "data": { "…": "…" } },
    { "input": "IE00B3RBWM25", "isin": "IE00B3RBWM25", "status": "ok", "name": "…", "data": { "…": "…" } },
    { "input": "LU1681043599", "isin": "LU1681043599", "status": "pending" }
  ]
}

Statuses

With wait: true the call waits (up to the 300-second limit) for cold ISINs that fit the time budget; the rest come back pending and are warmed in the background so the next call finds them.

Loading a universe

1. Validate ISINs locally (format and check digit) to avoid wasting entries.
2. Send batches of the plan's size; collect ok and not_found, queue pending for a retry after 60 seconds.
3. Store each payload with its expiresAt; refresh only expired rows, spread across the day.
4. Watch X-RateLimit-Remaining and pause below a floor.

The fund screener use case and the Next.js screener guide show the code. For a whole store dump on Scale, GET /export streams NDJSON in one request.