Move an existing app to impossibl

Start with one model call in a development environment. You need an impossibl API key and a model from the live catalog.

Update three settings

Setting	Use with impossibl
API key	Your impossibl workspace key, stored as `IMPOSSIBL_API_KEY`
OpenAI-compatible base URL	`https://api.impossibl.com/v1`
Model	A full catalog ID, such as `openai/gpt-4o-mini`

A provider key or a key from another gateway does not authenticate to impossibl. To keep paying your own provider account, authenticate with an impossibl key and add the provider credential separately through BYOK.

From OpenAI or another OpenAI-compatible gateway

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Keep your Chat Completions call and update the client:

import os
from openai import OpenAI

client = OpenAI(
    base_url="https://api.impossibl.com/v1",
    api_key=os.environ["IMPOSSIBL_API_KEY"],
)

response = client.chat.completions.create(
    model="openai/gpt-4o-mini",
    messages=[{"role": "user", "content": "Summarize the benefits of daily notes."}],
    max_tokens=256,
)
print(response.choices[0].message.content)

If you use Responses, keep full conversation history in input. Replace stored-response lookup or previous_response_id chaining with application-managed history.

From the Vercel AI SDK

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Configure an explicit provider that calls impossibl. A bare string model passed to the AI SDK uses its default gateway configuration, so changing only the model ID does not move your traffic.

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

const impossibl = createOpenAI({
  baseURL: "https://api.impossibl.com/v1",
  apiKey: process.env.IMPOSSIBL_API_KEY,
});

const { text } = await generateText({
  model: impossibl.chat("openai/gpt-4o-mini"),
  prompt: "Summarize the benefits of daily notes.",
});
console.log(text);

Install ai and @ai-sdk/openai if your project does not already use them. The explicit .chat() selects Chat Completions. See integrations for Responses configuration.

From OpenRouter

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Use the same OpenAI-compatible client configuration above. Copy model IDs from impossibl’s catalog even when the creator prefixes look familiar: model slugs, aliases, and availability can differ.Remove OpenRouter-specific routing fields and model suffixes from your request. Provider ordering, fallback model lists, plugins, and attribution headers do not configure impossibl routing. The gateway manages failover between serving routes for the model you request; see routing.

From Anthropic

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Set the Anthropic SDK base URL to https://api.impossibl.com without /v1, supply your impossibl key, and keep max_tokens in your Messages request. Full examples are in the Anthropic SDK guide.

From an older impossibl integration

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Continue to use https://api.impossibl.com/v1. The current docs do not introduce a /v2 API prefix. Your workspace key chooses the workspace for a request; switching workspaces in the console does not change what an existing key belongs to.Review the live model catalog for retirements and replacements. Check billing, BYOK balance rules, and API compatibility instead of assuming older behavior still applies.

Verify before switching traffic

Run a short text request and check its model, provider, and cost in logs.
Exercise the features you use: streaming completion, tool-result turns, multimodal input, and reasoning. Keep complete assistant tool-call objects when returning results.
Check error handling for invalid credentials, insufficient balance, and provider failures. Do not retry configuration errors indefinitely.
Compare output quality, latency, token usage, and cost with representative application inputs.
Deploy with a server-side key and bounded retries. Keep your prior client configuration available while you observe the first production requests.

See API keys, billing, and errors for operational details.

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Move an existing app to impossibl

Update three settings

From OpenAI or another OpenAI-compatible gateway

From the Vercel AI SDK

From OpenRouter

From Anthropic

From an older impossibl integration

Verify before switching traffic

​Update three settings

​From OpenAI or another OpenAI-compatible gateway

​From the Vercel AI SDK

​From OpenRouter

​From Anthropic

​From an older impossibl integration

​Verify before switching traffic

Update three settings

From OpenAI or another OpenAI-compatible gateway

From the Vercel AI SDK

From OpenRouter

From Anthropic

From an older impossibl integration

Verify before switching traffic