Steam Web API rate limit exceeded: the fix.

The Steam Web API Terms of Use set the limit at 100,000 calls to the Steam Web API per day, per key. Valve's list of response codes includes 429 Too Many Requests for rate-limited callers. Valve does not document a Retry-After header.

100,000 a day is about 69 calls a minute around the clock. Apps hit it by polling every user on a timer, by calling once per Steam ID instead of batching, and by retrying failures immediately, which multiplies the traffic exactly when Steam is already refusing it.

• Per-user polling: 2,000 users checked every 30 minutes is 96,000 calls a day on its own.
• One call per ID where the method accepts a comma-separated list (GetPlayerSummaries takes up to 100 Steam IDs).
• Immediate retries in a loop after a 429 or a 5xx.
• Calls that earn 403s: Valve applies stricter per-IP limits to traffic that keeps generating 403 responses.

Count your calls, cache every response for as long as the data stays valid, batch IDs, and back off when Steam pushes back. The code below does all four.

import time, requests
from functools import lru_cache

KEY = "YOUR_STEAM_WEB_API_KEY"
DAILY_BUDGET = 90_000          # stay under Valve's 100,000 with headroom
calls_today, day = 0, time.strftime("%Y-%m-%d")

def steam_get(url, params, tries=5):
    global calls_today, day
    if time.strftime("%Y-%m-%d") != day:
        calls_today, day = 0, time.strftime("%Y-%m-%d")
    if calls_today >= DAILY_BUDGET:
        raise RuntimeError("daily Steam budget used up")
    for attempt in range(tries):
        calls_today += 1
        r = requests.get(url, params={**params, "key": KEY}, timeout=10)
        if r.status_code != 429 and r.status_code < 500:
            r.raise_for_status()
            return r.json()
        time.sleep(min(60, 2 ** attempt))   # 1, 2, 4, 8, 16 s
    r.raise_for_status()

@lru_cache(maxsize=10_000)
def summaries(ids: tuple[str, ...]):
    # one call for up to 100 Steam IDs instead of 100 calls
    return steam_get("https://api.steampowered.com/ISteamUser/GetPlayerSummaries/v2/",
                     {"steamids": ",".join(ids)})

If the data you need is professional CS2 (matches, scores, player ratings, rankings), Steam does not have it at all, so no amount of budgeting helps. The CS2 API serves it from its own index, and its limits are published per plan with standard Retry-After and X-RateLimit headers on every 429.