Configuring Dynamic API Payloads

Step-by-Step Guide to Dynamic Payloads for Chat Completion APIs

Static payloads are fine for simple demos, but real apps need flexibility. A dynamic payload is a JSON object you build at runtime so you can change models, prompts, tools, and settings without editing code. This makes your chatbot scalable, adaptable, and easier to maintain.

1. What is a static payload?

A static payload is a fixed JSON you always send to the API:

{
  "org_id": "ORG_123",
  "chatbot_id": "BOT_456",
  "user_id": "USER_123",
  "variables": {
    "name": "abc"
  }
}

Problems with static payloads:

• Model, prompt, and tools are hardcoded.

• Changing behavior requires code edits and redeploys.

• Not suitable for multi-tenant or multi-model setups.

2. Why use a dynamic payload?

Dynamic payloads let you:

• Switch models (for cost vs. capability trade-offs).

• Update prompts per user language, role, or context.

• Add function-calling tools only when needed.

• Adjust temperature, token limits, or other runtime parameters.

• Keep optional fields out of the request unless required (keeps payloads small).

3. Core dynamic payload structure

Build a JSON at runtime with configuration fields. Example structure:

{
  "service": "openai",
  "configuration": {
    "model": "gpt-4o",
    "type": "chat",
    "prompt": "Act as a JSON response bot",
    "max_tokens": 1024,
    "temperature": 0.7
  },
  "apikey": "your-api-key"
}

Key fields to customize:

• model — which LLM to use (e.g., gpt-4o, gpt-3.5).

• prompt — the system/user instructions that define behavior.

• tools — optional list of functions or integrations.

• max_tokens — maximum response length.

• temperature — controls creativity/variance.

• other optional fields — e.g., response_count, log_probability.

4. Add tools (function calling) only when needed

If a response requires external logic (calculators, DB queries, third-party APIs), include a tools section dynamically:

"tools": [
  {
    "type": "function",
    "id": "66aa1347f6048aaaf9e5d34b",
    "name": "calculate_bmi",
    "description": "Calculate BMI from weight and height",
    "required": ["weight", "height"],
    "properties": {
      "weight": { "type": "number" },
      "height": { "type": "number" }
    }
  }
]

Only add tools when the current prompt or user action needs them — this keeps other requests lightweight.

5. Keep optional fields optional

Don’t send optional fields unless needed. Common optional fields include:

• system_prompt_version_id

• log_probability

• repetition_penalty

• response_count

Including unnecessary fields increases payload size and can complicate downstream handling.

6. Example: Build payload at runtime (pseudo-code)

function buildPayload(userContext) {
  const base = {
    service: "openai",
    configuration: {
      model: userContext.preferredModel || "gpt-4o",
      type: "chat",
      prompt: generatePrompt(userContext),
      max_tokens: userContext.maxTokens || 512,
      temperature: userContext.temperature ?? 0.5
    },
    apikey: process.env.API_KEY
  };

  if (userContext.needsTools) {
    base.configuration.tools = buildTools(userContext.toolsConfig);
  }

  if (userContext.includeTelemetry) {
    base.configuration.log_probability = 0;
  }

  return base;
}

7. Send responses to a webhook

Sometimes you don’t want the API response returned immediately in the API response.
Instead, you may want it delivered to another system — such as a workflow engine, backend service, automation tool, or event processor.

For these cases, you can configure the API to send its response directly to a webhook.

To receive responses on a webhook, include a response_format field in your payload:

"configuration" : {
    "response_format": {
        "type": "webhook",
        "cred": {
                "url": "// webhook",
                "headers": {
                        // your custom headers here
                }
         }
}

Field explanation

• type : Set to "webhook" to tell the system to deliver responses externally.

• cred.url : The webhook endpoint where the API response will be sent.

• cred.headers: Custom headers sent with the webhook request (stringified JSON). Useful for authentication tokens, or content type.

8. Testing and safety tips

• Validate dynamic values before sending (model names, numeric ranges).

• Sanitize user input inserted into prompts to avoid injection issues.

• Rate-limit and monitor usage when switching to more powerful/expensive models.

• Use feature flags or admin controls to test new models or tools safely.

9. Final takeaway

Dynamic payloads give your chatbot freedom.
You control behavior, tools, and models at runtime — without rebuilding or redeploying.

This is how you scale AI systems intelligently.