Smart Routing

Every CAPTCHA task submitted to uCaptcha is routed through a scoring algorithm that evaluates all available providers and selects the best one based on speed, cost, and reliability. The router adapts in real time using observed performance data, ensuring optimal provider selection for every request.

How It Works

The routing algorithm executes the following steps for each incoming task:

1. Gather candidates — Identify all providers that support the requested task type.
2. Collect real-time stats — For each candidate, retrieve current metrics:
   • Cost: Per-task cost based on an EWMA (exponentially weighted moving average) of observed pricing
   • Speed: Rolling average solve time from recent completions
   • Reliability: Success rate over the recent window
3. Apply Pareto filter — Remove any provider that is both slower and more expensive than another candidate. Only non-dominated providers remain.
4. Score remaining candidates:
   • Normalize cost and speed values to a 0-1 range across the candidate set
   • Calculate baseScore = (speedWeight / 100) * speedScore + (costWeight / 100) * priceScore
   • Calculate reliabilityMultiplier = 0.3 + 0.7 * (successRate / 100)
   • Final score: totalScore = baseScore * reliabilityMultiplier
5. Apply recycle bias — If the user has a recycled provider API key with remaining balance, boost that provider’s score by up to 15%.
6. Route — Send the task to the highest-scoring provider.

Note

Reliability is always factored in as a multiplier, regardless of your speed/cost slider position. A provider with a 50% success rate will never outscope a reliable alternative, even if it is cheaper or faster.

Speed/Cost Priority Slider

Each API key has a speed/cost priority value from 0 to 100 that controls the tradeoff between fast and cheap:

Value	Behavior
0	Cheapest providers preferred
50	Balanced (default)
100	Fastest providers preferred

The slider maps directly to the speedWeight in the scoring formula. A costWeight is derived as 100 - speedWeight. At value 50, speed and cost contribute equally to the score.

Per-Key Settings

Each API key has independent routing configuration. This allows you to run multiple strategies simultaneously:

• One key optimized for speed (high-priority scraping)
• Another key optimized for cost (batch processing)
• A third with custom settings for a specific use case

Configure routing per key in the Telegram Mini App under the API tab.

Selection Mode Override

Override routing behavior on a per-request basis using the selectionMode parameter in your createTask call:

Selection Mode	Speed Weight	Description
autoCheapest	10	Strongly prefer cheapest provider
autoFastest	90	Strongly prefer fastest provider
autoMostReliable	50	Balanced, but reliability has standard weight
priority	50	Same as autoMostReliable

Example

{
  "clientKey": "YOUR_API_KEY",
  "task": {
    "type": "ReCaptchaV2TokenProxyLess",
    "websiteURL": "https://example.com",
    "websiteKey": "6Le-wvkSAAAAAPBMRTvw0Q4Muexq9bi0DJwx_mJ-"
  },
  "selectionMode": "autoFastest"
}

Forcing a Specific Provider

If you need to bypass routing entirely and send a task to a specific provider, use the provider parameter:

{
  "clientKey": "YOUR_API_KEY",
  "task": {
    "type": "ReCaptchaV2TokenProxyLess",
    "websiteURL": "https://example.com",
    "websiteKey": "6Le-wvkSAAAAAPBMRTvw0Q4Muexq9bi0DJwx_mJ-"
  },
  "provider": "capsolver"
}

Valid provider identifiers: 2captcha, capsolver, anticaptcha, capmonster, multibot, ucaptcha.

Caution

Forcing a provider skips all routing logic, including health checks. If the specified provider is down or does not support the task type, the request will fail.

Recycled Key Bias

When you submit your own provider API keys through Key Recycling, the routing algorithm gives a small preference (up to 15% score boost) to providers where your recycled key has remaining balance. This maximizes utilization of your existing provider balances while still maintaining intelligent routing.

The bias is capped to prevent recycled keys from overriding a significantly better provider choice. If another provider scores substantially higher on speed, cost, or reliability, the router will still select it.

Failover

If the selected provider fails to accept or solve a task, uCaptcha does not automatically retry with a different provider. The failure is returned to the caller. To implement retry logic with a fallback provider, resubmit the task and optionally exclude the failed provider or force a different one using the provider parameter.