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API keys are shown once at creation and cannot be retrieved afterward — this is a security measure. Go to your Dashboard, revoke the lost key, and generate a new one. Your usage history and billing are tied to your merchant account, not individual keys, so nothing is lost.

Sign into the Dashboard with your current key. Under the API Keys section, click "Revoke" on the old key. Then generate a new key. Best practice: update your application with the new key before revoking the old one to avoid downtime.

Common causes:
1. Missing header — requests must include X-API-Key: your_live_key.
2. Wrong key type — use a live key for production requests and a free evaluation key only for safe integration proof.
3. Revoked key — check your Dashboard for key status.
4. Whitespace — ensure no trailing spaces or newlines in the header value.
See the Authentication docs for full details.

A 403 means your plan doesn't include that endpoint. For example, label creation requires the Growth plan or higher, and BYOK requires Pro. Check the endpoint summary for plan requirements. Start from Pricing or open billing tools from your Dashboard. If self-serve billing is not enabled for your account yet, email [email protected] and we will handle the change directly.

The free proof path is IP-limited at 30 req/10 sec. Paid plans add progressively higher monthly caps and managed throughput, with Enterprise shaped to your workload.
Check response headers X-RateLimit-Remaining on every request, and see Pricing for the current plan matrix. See Rate Limit docs for implementation details.

A 429 means you've exceeded your current limit. No data is lost and no extra charges apply — the request is simply rejected. The response includes a retry_after field (in seconds). Wait that long, then retry. If this is happening regularly, move to a higher-throughput plan or contact support so we can fit the workload correctly.

Go to your Dashboard and open billing tools. If self-serve billing is enabled for your account, you can upgrade, downgrade, update your card, or change your billing email there. If not, email [email protected] and we will handle it directly.

Open billing tools from your Dashboard. If self-serve billing is enabled for your account, you can cancel there. Otherwise email [email protected]. Your API key stays active until the end of the current billing period — you won't lose access mid-month. No cancellation fees, no contracts.

We don't offer refunds for partially used billing periods, but you can cancel at any time and your access continues until the period ends. If you were charged in error or have an exceptional circumstance, use the contact form below and we'll resolve it.

BYOK is available on Pro and Enterprise plans. Steps:
1. Get credentials from the USPS Developer Portal (client ID, client secret, CRID, MID).
2. Store them via POST /api/byok/credentials.
3. Verify with POST /api/byok/verify.
Your credentials are AES-GCM encrypted at rest. See the BYOK docs for the full API reference.

Run GET /api/byok/status to check credential health. Common issues:
1. Expired USPS token — we auto-refresh, but if your client secret changed on the USPS portal, re-submit credentials.
2. Wrong CRID/MID — these must match your USPS Developer Portal registration exactly.
3. Plan mismatch — BYOK requires Pro ($199/mo) or Enterprise.
If status shows "verified" but requests fail, the issue is likely on the USPS side. Check OAuth troubleshooting.

Free proof path: IP-limited at 30 req/10 sec, safe for validating addresses, comparing rates, and proving the integration before you buy.
Production: Paid plans, higher rate limits, managed tracking routes, protected label workflows, BYOK, and request-access pickup.
Get a free API key — no credit card required. Upgrade when you're ready to ship.

The fastest way — validate an address with curl:

Address validation works without a key (free tier). For authenticated endpoints, add -H "X-API-Key: your_key_here". Or use our live API playground. SDKs available for Python and Node.js.

The free proof path is IP-rate-limited at 30 req/10 sec and includes these read-only endpoint families:
1. GET /api/address/validate and POST /api/address/validate — address validation
2. POST /api/address/extract — guided address extraction
3. GET /api/address/city-state — city/state lookup by ZIP
4. POST /api/rates and POST /api/international-prices — rate shopping
5. GET /api/service-standards, GET /api/shipping-options, and GET /api/locations — planning helpers
Tracking, labels, pickup, BYOK, dashboard, and other protected workflows require an API key. See the full endpoint table.