OpenRouter Broadcast

If you’re using OpenRouter, you can send traces to Fallom automatically using OpenRouter’s Broadcast feature. No SDK installation required.

Broadcast provides observability only. For Model A/B Testing and Prompt Management, use the Fallom SDK.

What You Get

Feature	Broadcast	SDK
Trace logging	✅	✅
Token tracking	✅	✅
Cost tracking	✅	✅
Session grouping	✅	✅
Customer tracking	✅	✅
Model A/B Testing	❌	✅
Prompt Management	❌	✅
Prompt A/B Testing	❌	✅

Setup (5 minutes)

1. Get Your Fallom API Key

Go to app.fallom.com/settings and copy your API key.

2. Configure OpenRouter Broadcast

Go to OpenRouter Broadcast Settings
Click Add destination
Select OTel Collector
Enter:

Endpoint:

https://broadcast.fallom.com/v1/traces

Headers:

{
  "Authorization": "Bearer YOUR_FALLOM_API_KEY"
}

Click Save

That’s it! All your OpenRouter requests will now appear in Fallom.

Alternative: Per-Request Headers

You can also set broadcast headers on each request instead of configuring in OpenRouter’s dashboard:

import OpenAI from "openai";

const openrouter = new OpenAI({
  apiKey: process.env.OPENROUTER_API_KEY,
  baseURL: "https://openrouter.ai/api/v1",
  defaultHeaders: {
    "X-Broadcast-URL": "https://broadcast.fallom.com/v1/traces",
    "X-Broadcast-Auth": "Bearer YOUR_FALLOM_API_KEY",
  },
});

const response = await openrouter.chat.completions.create({
  model: "openai/gpt-4o-mini",
  messages: [{ role: "user", content: "Hello!" }],
  // @ts-ignore - OpenRouter-specific fields
  session_id: "conversation-123",
  user: "customer-456",
});

This approach is useful for testing or when you want different API keys per environment.

Adding Session & User Tracking

Include session_id and user in your OpenRouter request body:

Fetch
OpenAI SDK
Vercel AI SDK
Python

const response = await fetch("https://openrouter.ai/api/v1/chat/completions", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${OPENROUTER_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    model: "openai/gpt-4o-mini",
    messages: [{ role: "user", content: "Hello!" }],
    
    // These get included in your Fallom traces
    session_id: "conversation-123",  // Groups related requests
    user: "customer-456",            // Identifies end users
  }),
});

import OpenAI from "openai";

const client = new OpenAI({
baseURL: "https://openrouter.ai/api/v1",
apiKey: process.env.OPENROUTER_API_KEY,
});

const response = await client.chat.completions.create({
model: "openai/gpt-4o-mini",
messages: [{ role: "user", content: "Hello!" }],
// @ts-ignore - OpenRouter-specific fields
session_id: "conversation-123",
user: "customer-456",
});

Vercel AI SDK doesn’t pass custom body fields to OpenRouter. For session tracking with Vercel AI SDK + Broadcast, use the Fallom SDK wrapper or the OpenAI SDK tab below.

// Recommended: Use Fallom SDK session wrapper for Vercel AI SDK
import fallom from "@fallom/trace";
import * as ai from "ai";
import { createOpenAI } from "@ai-sdk/openai";

await fallom.init({ apiKey: "your-fallom-api-key" });

const session = fallom.session({
  configKey: "my-app",
  sessionId: "conversation-123",
  customerId: "customer-456",
});

const { generateText } = session.wrapAISDK(ai);

const openrouter = createOpenAI({
  baseURL: "https://openrouter.ai/api/v1",
  apiKey: process.env.OPENROUTER_API_KEY,
});

const { text } = await generateText({
  model: openrouter("openai/gpt-4o-mini"),
  prompt: "Hello!",
});

from openai import OpenAI

client = OpenAI(
base_url="https://openrouter.ai/api/v1",
api_key="your-openrouter-key"
)

response = client.chat.completions.create(
model="openai/gpt-4o-mini",
messages=[{"role": "user", "content": "Hello!"}],
extra_body={
"session_id": "conversation-123",
"user": "customer-456"
}
)

Available Fields

Field	Description	Fallom Mapping
`session_id`	Groups related requests (conversations, agent runs)	`session_id`
`user`	Identifies end users (up to 128 chars)	`customer_id`

These fields must be in the request body, not headers. OpenRouter only broadcasts body fields to OTEL destinations.

Structured Output (JSON Mode) with Broadcast

For structured output with broadcast, use the OpenAI SDK with response_format:

import OpenAI from "openai";

const openrouter = new OpenAI({
  apiKey: process.env.OPENROUTER_API_KEY,
  baseURL: "https://openrouter.ai/api/v1",
  defaultHeaders: {
    "X-Broadcast-URL": "https://broadcast.fallom.com/v1/traces",
    "X-Broadcast-Auth": "Bearer YOUR_FALLOM_API_KEY",
  },
});

const response = await openrouter.chat.completions.create({
  model: "openai/gpt-4o-mini",
  messages: [
    {
      role: "system",
      content:
        "Output JSON only. Format: {name: string, price: number, description: string}",
    },
    { role: "user", content: "Generate a tech gadget." },
  ],
  response_format: { type: "json_object" },
  // @ts-ignore - OpenRouter extensions
  session_id: "conversation-123",
  user: "customer-456",
});

const product = JSON.parse(response.choices[0].message.content!);
console.log(product); // { name: "...", price: 99.99, description: "..." }

For Vercel AI SDK’s generateObject/streamObject with session tracking, use the Fallom SDK wrapper instead of broadcast. The SDK wrapper provides full tracing with fallom.session().

What Gets Traced

Every OpenRouter request automatically includes:

Field	Description
Model	Full model path (e.g., `openai/gpt-4o`)
Provider	Which provider served the request
Duration	Request latency
Tokens	Input, output, cached tokens
Cost	OpenRouter’s cost calculation
Prompts	Input messages
Completions	Model response
Session	Your session_id (if provided)
Customer	Your user ID (if provided)

Troubleshooting

Traces not appearing

Verify Broadcast is enabled in OpenRouter settings
Check the endpoint is exactly https://broadcast.fallom.com/v1/traces
Confirm your API key starts with flm_
Check the Authorization header format: Bearer YOUR_API_KEY (with a space)

401 Unauthorized

Your API key is invalid or the header format is wrong:

{
  "Authorization": "Bearer flm_xxxxx"
}

Missing session or customer data

Include session_id and user in the request body, not as headers.

Next Steps

OpenRouter SDK

Use SDK for A/B testing and prompts.

View Dashboard

See your traces.

Getting Started

Features

TypeScript Integrations

Python Integrations

AI Coding Tools

No-Code Integrations

OpenRouter Broadcast

What You Get

Setup (5 minutes)

1. Get Your Fallom API Key

2. Configure OpenRouter Broadcast

Alternative: Per-Request Headers

Adding Session & User Tracking

Available Fields

Structured Output (JSON Mode) with Broadcast

What Gets Traced

Troubleshooting

Traces not appearing

401 Unauthorized

Missing session or customer data

Next Steps

OpenRouter SDK

View Dashboard

​What You Get

​Setup (5 minutes)

​1. Get Your Fallom API Key

​2. Configure OpenRouter Broadcast

​Alternative: Per-Request Headers

​Adding Session & User Tracking

​Available Fields

​Structured Output (JSON Mode) with Broadcast

​What Gets Traced

​Troubleshooting

​Traces not appearing

​401 Unauthorized

​Missing session or customer data

​Next Steps

OpenRouter SDK

View Dashboard

What You Get

Setup (5 minutes)

1. Get Your Fallom API Key

2. Configure OpenRouter Broadcast

Alternative: Per-Request Headers

Adding Session & User Tracking

Available Fields

Structured Output (JSON Mode) with Broadcast

What Gets Traced

Troubleshooting

Traces not appearing

401 Unauthorized

Missing session or customer data

Next Steps