Respan Observability

Respan (formerly Keywords AI) is an LLM engineering platform for observability, evaluation, and gateway routing. Respan integrates with the AI SDK to provide:

  • Tracing for each AI SDK call (input, output, token usage, cost, latency)
  • Tool call and structured output capture
  • Optional gateway routing across 250+ models behind a single endpoint

Setup

The AI SDK supports tracing via OpenTelemetry. With the VercelAIInstrumentor from @respan/instrumentation-vercel, traces are exported to Respan automatically.

Install 

npm install ai @ai-sdk/openai @respan/respan @respan/instrumentation-vercel

Configure environment variables

.env
RESPAN_API_KEY="your-respan-api-key"

Get your API key from platform.respan.ai.

Initialize Respan

Create instrumentation.ts at the root of your Next.js project:

instrumentation.ts
import { Respan } from '@respan/respan';
import { VercelAIInstrumentor } from '@respan/instrumentation-vercel';


export async function register() {
  const respan = new Respan({
    apiKey: process.env.RESPAN_API_KEY,
    instrumentations: [new VercelAIInstrumentor()],
  });
  await respan.initialize();
}

Then mark the SDK packages as server-external in next.config.ts:

next.config.ts
import type { NextConfig } from 'next';


const nextConfig: NextConfig = {
  serverExternalPackages: ['@respan/respan', '@respan/instrumentation-vercel'],
};


export default nextConfig;

Generate text with telemetry enabled 

import { openai } from '@ai-sdk/openai';
import { generateText } from 'ai';


const result = await generateText({
  model: openai('gpt-4o-mini'),
  prompt: 'Tell me a joke about AI',
  experimental_telemetry: { isEnabled: true },
});

Spans appear in the Respan traces page with input, output, token usage, and cost.

Gateway routing (optional)

To use Respan as a unified gateway across providers, point any AI SDK provider at https://api.respan.ai/api with your RESPAN_API_KEY. Provider keys are managed in Respan; only the Respan key is needed at runtime.

import { createOpenAI } from '@ai-sdk/openai';
import { generateText } from 'ai';


const provider = createOpenAI({
  apiKey: process.env.RESPAN_API_KEY!,
  baseURL: 'https://api.respan.ai/api',
});


const result = await generateText({
  model: provider('gpt-4.1-nano'),
  prompt: 'Tell me a joke about AI',
  experimental_telemetry: { isEnabled: true },
});

The same gateway endpoint accepts Anthropic and Google models when used with their respective AI SDK providers (createAnthropic, createGoogleGenerativeAI) and the matching base path (/api/anthropic, /api/google/gemini).

Resources