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Documentation Index

Fetch the complete documentation index at: https://docs.nixflex.com/llms.txt

Use this file to discover all available pages before exploring further.

Nixflex applies rate limits to protect the platform and ensure fair use. Most applications stay well under these limits, but if you’re building high-volume integrations, plan around them.

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API request limits

Per API key:
Endpoint groupLimit
Read operations (GET)600 requests per minute
Write operations (POST, PUT, PATCH, DELETE)120 requests per minute
Authentication endpoints (POST /v1/keys)10 requests per hour
Headers on every response tell you where you stand: 
X-RateLimit-Limit: 600
X-RateLimit-Remaining: 587
X-RateLimit-Reset: 1715900060
X-RateLimit-Reset is a Unix timestamp when the window resets.

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When you hit the limit

You get a 429 response: 
{
  "error": {
    "type": "rate_limit_error",
    "code": "rate_limit_exceeded",
    "message": "Rate limit exceeded. Try again in 12 seconds.",
    "details": {
      "retry_after": 12
    }
  }
}
retry_after tells you how long to wait. Honour it.

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Concurrent call limits

The number of calls running simultaneously per account:
TierConcurrent calls
Pay-as-you-go10
Starter25
Scale100
EnterpriseCustom
If you trigger more outbound calls than your concurrency limit allows, they queue automatically. Inbound calls beyond the limit hear a busy signal. To raise your concurrent call limit, contact support@nixflex.com.

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Batch campaign concurrency

Within a batch campaign, the engine launches calls in waves up to your account’s concurrent call limit. A 1,000-recipient campaign on a 25-concurrent plan takes roughly the average call duration × (1,000 / 25) to complete. You can also throttle a campaign deliberately: 
{
  "agent_id": "agent_xxx",
  "recipients": [...],
  "max_concurrent": 5
}
Useful when you want to keep some headroom for inbound calls.

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SMS rate limits

SMS is rate-limited by Twilio, not Nixflex. Default: 1 message per second per sending number. For high-volume SMS:
  • Add multiple sending numbers (the engine round-robins them)
  • Request a higher Twilio MPS limit from Twilio support
  • Use SMS campaigns, which respect Twilio’s pacing automatically

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Webhook delivery limits

Webhooks fire as fast as your endpoint can accept them, with no Nixflex-side throttle. If your server is slow:
  • Receive the webhook quickly (return 2xx immediately)
  • Process the data in a background queue
  • Don’t do heavy work inside the webhook handler

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When you need more

If you’re running into limits regularly, that’s a signal you’ve outgrown the default tier. Email support@nixflex.com and we’ll raise your limits or move you to a custom plan.