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When a request fails, the response sets success to false and returns an error object with a machine-readable code and a human-readable message. All error responses follow the same envelope described in Response format.

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Error code reference

Error codeStatusMeaning
MISSING_API_KEY401Authorization header is missing or malformed
INVALID_API_KEY401API key not found or has been revoked
PLAN_REQUIRED403Endpoint requires a higher-tier plan
QUOTA_EXCEEDED429Monthly call limit reached
NOT_FOUND404Route or resource does not exist
SERVER_ERROR500Unexpected error on the server

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Troubleshooting

What it means: Your request did not include an Authorization header, so the API cannot identify your account.How to fix it: Add your API key to every request using the Authorization header with the Bearer scheme:
curl https://api.ngnmarket.com/v1/market/snapshot \
  -H "Authorization: Bearer ngm_live_YOUR_KEY"
All endpoints except /health require authentication. If you are using an HTTP client or library, check that it is not stripping the Authorization header on redirects. Some clients drop headers by default when following a 301 or 302 response.
What it means: The key in your Authorization header was not recognised. This happens when the key does not exist, has been deleted, or has been revoked.How to fix it:
  1. Open your developer dashboard and confirm the key is still active.
  2. Copy the key value directly from the dashboard to rule out a typo or truncation.
  3. Check that you are using the full key, including the ngm_live_ prefix.
  4. If you recently rotated or deleted a key, update all integrations that used the old one.
If your key appears valid in the dashboard but still returns this error, contact support.
What it means: The endpoint you called requires a higher plan than your current one. The error response includes required_plan and current_plan so you know exactly what is needed:
{
  "success": false,
  "error": {
    "code": "PLAN_REQUIRED",
    "message": "This endpoint requires a starter plan or higher.",
    "required_plan": "starter",
    "current_plan": "free"
  }
}
How to fix it:
  • Check the Plans page to see which endpoints each tier unlocks.
  • Upgrade to at least the plan named in required_plan from your developer dashboard.
  • If you think you are already on the required plan, confirm your plan tier in the dashboard.
What it means: Your account has used all of its monthly API calls. No further requests will succeed until your quota resets or you upgrade. This error includes a meta object so you can confirm the reset date:
{
  "success": false,
  "error": {
    "code": "QUOTA_EXCEEDED",
    "message": "Monthly call limit of 100,000 reached. Resets on 2026-05-01T00:00:00.000Z."
  },
  "meta": {
    "plan": "starter",
    "calls_used": 100000,
    "calls_remaining": 0,
    "reset_at": "2026-05-01T00:00:00.000Z"
  }
}
How to fix it:
  • Wait for the reset. Your quota resets on the 1st of the next month at midnight UTC. The exact time is in meta.reset_at.
  • Upgrade your plan. Log in to your developer dashboard and select a higher plan. Upgrades take effect immediately. See Plans for limits and pricing.
To avoid this in future, monitor meta.calls_remaining and reduce usage or upgrade before you hit zero.
What it means: The URL path you requested does not match any route on the API.How to fix it:
  1. Check the API Reference to confirm the correct path and HTTP method.
  2. Make sure any path parameters like :symbol are substituted correctly, for example /v1/companies/DANGCEM not /v1/companies/:symbol.
  3. Confirm you are using the correct base URL: https://api.ngnmarket.com.
  4. Check for trailing slashes or typos. Paths are case-sensitive.
What it means: An unexpected error occurred on the NGN Market servers. This is not caused by your request and does not count against your quota.How to fix it:
  1. Retry the request after a short delay. Most server errors are transient.
  2. If the error persists for several minutes, check the NGN Market status page for any active incidents.
  3. If you can reliably reproduce the error, report it to support with the endpoint, request details, and approximate time of the failure.

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Frequently asked questions

It depends on the error. Requests that fail authentication (MISSING_API_KEY or INVALID_API_KEY) and requests blocked for exceeding your quota (QUOTA_EXCEEDED) do not count against your limit. Requests that pass authentication and quota checks but return PLAN_REQUIRED, NOT_FOUND, or SERVER_ERROR are counted because they were already validated.
The API does not send proactive notifications, but you can build your own alerting by reading meta.calls_remaining in every response. When it falls below a threshold you define, trigger an alert in your application or monitoring system.
Confirm the header is formatted exactly as Authorization: Bearer ngm_live_YOUR_KEY with a single space after Bearer. Some HTTP clients modify or strip headers. Log the outgoing request headers to verify they are sent correctly, and check that no whitespace or newline characters were introduced when copying the key.