Vercel AI Gateway is a day 0 launch partner for the OpenResponses API, an open-source specification from OpenAI for multi-provider AI interactions.
OpenResponses provides a unified interface for text generation, streaming, tool calling, image input, and reasoning across providers.
AI Gateway supports OpenResponses for:
Text generation: Send messages and receive responses from any supported model.
Streaming: Receive tokens as they're generated via server-sent events.
Tool calling: Define functions that models can invoke with structured arguments.
Image input: Send images alongside text for vision-capable models.
Reasoning: Enable extended thinking with configurable effort levels.
Provider fallbacks: Configure automatic fallback chains across models and providers.
Use OpenResponses with your AI Gateway key, and switch models across providers by changing the model string.
const response = await fetch('https://ai-gateway.vercel.sh/v1/responses', {
method: 'POST',
headers: {
'Content-Type': 'application/json',
Authorization: `Bearer ${process.env.VERCEL_AI_GATEWAY_KEY}`,
},
body: JSON.stringify({
model: 'anthropic/claude-sonnet-4.5',
input: [
{
type: 'message',
role: 'user',
content: 'Explain quantum computing in one sentence.',
}
],
}),
});
You can also use OpenResponses for more complex cases, like tool calling.
const response = await fetch('https://ai-gateway.vercel.sh/v1/responses', {
method: 'POST',
headers: {
'Content-Type': 'application/json',
Authorization: `Bearer ${process.env.VERCEL_AI_GATEWAY_KEY}`,
},
body: JSON.stringify({
model: 'zai/glm-4.7',
input: [{ type: 'message', role: 'user', content: 'What is the weather in SF?' }],
tools: [{
type: 'function',
name: 'get_weather',
description: 'Get current weather for a location',
parameters: {
type: 'object',
properties: { location: { type: 'string' } },
required: ['location'],
},
}],
}),
});
Read the OpenResponses API documentation or view the specification.