Errors

Errors come back as an HTTP status code with a JSON body containing a message.

Status	Body (example)	Cause	Retry?
400 Bad Request	{"message": "..."}	Invalid parameters: unknown source, bad date format, unsupported interval, missing credentials for a source that needs them	No: fix the request
403 Forbidden	{"message": "Forbidden"}	Missing or invalid x-api-key header, the key was deleted (for example after cancelling a plan), or it is paused because a renewal payment failed (see Billing)	No: check the key and your subscription in the dashboard
429 Too Many Requests	{"message": "Limit Exceeded"}	Monthly allowance for your plan is used up	After the monthly reset, or upgrade. See Plans & Limits
429 Too Many Requests	{"message": "Too Many Requests"}	Requests sent faster than your plan's rate	Yes, after a short pause
500 Internal Server Error	{"message": "..."}	The upstream data source failed or returned an error	Yes, with backoff
504 Gateway Timeout	{"message": "Endpoint request timed out"}	The request took too long, usually a very large range or many tickers	Yes, after splitting the request

Retrying safely

Retry only 429 Too Many Requests (rate), 500 and 504. Wait between attempts and increase the wait each time:

import time
import requests

def fetch(payload, retries=4):
    for attempt in range(retries):
        r = requests.post(URL, headers=HEADERS, json=payload, timeout=130)
        if r.status_code == 200:
            return r.json()
        if r.status_code == 429 and r.json().get("message") == "Limit Exceeded":
            raise RuntimeError("Monthly allowance used up")
        if r.status_code in (429, 500, 504):
            time.sleep(2 ** attempt)
            continue
        r.raise_for_status()
    r.raise_for_status()

Don't retry 400 or 403: the same request will fail again.