Spending Limits — Management API: Keys & Billing

Control Your API Costs

Spending limits are your financial safety net. They set a ceiling beyond which API requests are refused, preventing unexpected charges at the end of the month. The Management API lets you view and set these limits programmatically.

View Current Limits

curl "https://management-api.x.ai/v1/billing/teams/$TEAM_ID/postpaid/spending-limits" \
  -H "Authorization: Bearer $MANAGEMENT_API_KEY"

The response shows the current cycle ceiling and your current consumption—so, by difference, your remaining margin. This is the only number that matters day-to-day: a ceiling without consumption data doesn’t tell you whether you’re at 10% or 95% of your budget.

Set Limits

curl -X POST "https://management-api.x.ai/v1/billing/teams/$TEAM_ID/postpaid/spending-limits" \
  -H "Authorization: Bearer $MANAGEMENT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "monthlyLimit": 500.00
  }'

Behavior When Exceeded

Here’s the reassuring part, and it’s worth stating explicitly: hitting the limit never results in overbilling. Requests are refused, not billed beyond the cap. The risk shifts from financial to availability—which is exactly what you want, because an outage gets diagnosed and fixed in minutes, whereas an unexpected bill is discovered too late.

When consumption reaches the set limit:

API requests are refused with a specific error code
API keys remain active but inference calls fail
The limit resets at the start of the next billing cycle

Limit Strategy by Environment

For a team with multiple projects, the limit should reflect the risk specific to each environment. In development, the typical danger is an accidental request loop—a test script running all night—and a low limit of $50 to $100 turns that error into a $10 incident rather than a $1,000 surprise. Staging handles load tests, which legitimately consume more: a moderate limit of $200 to $500 leaves room for test campaigns while keeping a guardrail. Production, however, should never be throttled to the point of refusing client requests: a higher limit ($1,000 and beyond, depending on your traffic) comes with active monitoring—the alert protects you, while the limit is just the last-resort safety net.

View Current Charges

To see where you stand in the current cycle:

curl "https://management-api.x.ai/v1/billing/teams/$TEAM_ID/postpaid/invoice/preview" \
  -H "Authorization: Bearer $MANAGEMENT_API_KEY"

This endpoint returns charges accumulated since the start of the cycle. Compared to the number of days elapsed, it gives you more than a snapshot: a projection. Consuming 40% of the budget one-third into the month is healthy; the same 40% at one-tenth of the month signals an overrun, and you still have twenty-seven days to act.

Automate Cost Monitoring

Threshold Alert Script

import requests

MANAGEMENT_API = "https://management-api.x.ai"
MGMT_KEY = "xai-mgmt-..."
TEAM_ID = "team-..."
ALERT_THRESHOLD = 0.80  # Alert at 80% of limit

# Get the limit
limits_resp = requests.get(
    f"{MANAGEMENT_API}/v1/billing/teams/{TEAM_ID}/postpaid/spending-limits",
    headers={"Authorization": f"Bearer {MGMT_KEY}"}
)
monthly_limit = limits_resp.json().get("monthlyLimit", 0)

# Get current consumption
preview_resp = requests.get(
    f"{MANAGEMENT_API}/v1/billing/teams/{TEAM_ID}/postpaid/invoice/preview",
    headers={"Authorization": f"Bearer {MGMT_KEY}"}
)
current_spend = preview_resp.json().get("totalAmount", 0)

# Check threshold
if monthly_limit > 0:
    ratio = current_spend / monthly_limit
    if ratio >= ALERT_THRESHOLD:
        print(f"ALERT: {ratio*100:.1f}% of limit reached")
        print(f"  Spend: ${current_spend:.2f} / ${monthly_limit:.2f}")
        # Send notification

Integration with Monitoring

Combine the charge preview with your monitoring solution (Grafana, Datadog, etc.) to create real-time cost dashboards:

# Get current amount to send to your metrics system
CURRENT_SPEND=$(curl -s "https://management-api.x.ai/v1/billing/teams/$TEAM_ID/postpaid/invoice/preview" \
  -H "Authorization: Bearer $MANAGEMENT_API_KEY" | python3 -c "import sys,json; print(json.load(sys.stdin).get('totalAmount', 0))")

echo "xai.billing.current_spend:$CURRENT_SPEND|g" | nc -u -w1 localhost 8125

Adjust Limits Dynamically

The limit isn’t set in stone for the billing cycle—and that’s a good thing, because product life doesn’t follow the accounting calendar. Before an expected traffic spike, product launch, or marketing campaign, temporarily increase the limit: nothing worse than a paid campaign sending users to a service whose API refuses requests due to a reached ceiling. Conversely, if the month’s budget is already spent faster than expected, lowering the limit for the rest of the cycle turns drift into a controlled constraint. The most critical case remains a cost incident—a loop in production, detected abuse: lowering the limit immediately is your emergency stop button, the one that stops the bleeding while you find the cause.

# Temporarily increase for a launch
curl -X POST "https://management-api.x.ai/v1/billing/teams/$TEAM_ID/postpaid/spending-limits" \
  -H "Authorization: Bearer $MANAGEMENT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"monthlyLimit": 2000.00}'

# Reset normal limit after the spike
curl -X POST "https://management-api.x.ai/v1/billing/teams/$TEAM_ID/postpaid/spending-limits" \
  -H "Authorization: Bearer $MANAGEMENT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"monthlyLimit": 500.00}'

Key Takeaways

GET and POST on /v1/billing/teams/{teamId}/postpaid/spending-limits to view and set limits
When the limit is exceeded, API requests are refused (no overbilling)
The charge preview (invoice/preview) lets you track consumption in real time
Automate threshold alerts to anticipate overruns
Adapt limits by environment (dev, staging, production)