Flux RouterDocumentation

Migrate from OpenRouter

Move from OpenRouter to Flux. Both are OpenAI-compatible gateways, so it is a base URL, key and model swap.

OpenRouter and Flux are both OpenAI-compatible gateways, so migrating is the same kind of swap you would do between any two OpenAI-compatible endpoints. You change three things:

  1. Base URL to https://api.fluxrouter.ai/v1
  2. API key to your Flux key (sk-... from the dashboard)
  3. Model to flux-auto (or a specific flux-* id)

The OpenAI SDK, the endpoints, and the request and response JSON stay the same.

Get a Flux key

Sign up at /auth/sign-up and copy your key. It looks like sk-.... Get your key walks through it. The examples below read it from a FLUX_API_KEY environment variable.

Migrate the Python SDK

Before (OpenRouter)

python
from openai import OpenAI

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

response = client.chat.completions.create(
    model="anthropic/claude-sonnet-4-5",
    messages=[{"role": "user", "content": "Say hello."}],
)

print(response.choices[0].message.content)

After (Flux)

python
from openai import OpenAI

client = OpenAI(
    api_key="sk-...",                          # your Flux key
    base_url="https://api.fluxrouter.ai/v1",   # changed base URL
)

response = client.chat.completions.create(
    model="flux-auto",                         # let Flux route, or pin a flux-* id
    messages=[{"role": "user", "content": "Say hello."}],
)

print(response.choices[0].message.content)

Migrate the Node SDK

Before (OpenRouter)

ts
import OpenAI from "openai";

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

const response = await client.chat.completions.create({
  model: "anthropic/claude-sonnet-4-5",
  messages: [{ role: "user", content: "Say hello." }],
});

console.log(response.choices[0].message.content);

After (Flux)

ts
import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.FLUX_API_KEY,            // your Flux key
  baseURL: "https://api.fluxrouter.ai/v1",     // changed base URL
});

const response = await client.chat.completions.create({
  model: "flux-auto",                          // let Flux route, or pin a flux-* id
  messages: [{ role: "user", content: "Say hello." }],
});

console.log(response.choices[0].message.content);

Mapping model ids

On OpenRouter you pass provider-prefixed model ids like anthropic/claude-sonnet-4-5 or openai/gpt-4o. On Flux you pass a Flux alias instead:

  • flux-auto (recommended): Flux picks among vetted models for each kind of task, cost-aware, so you usually do not hand-pick a model at all. This is the main difference in day-to-day use: with OpenRouter you choose the model; with flux-auto, Flux chooses for you.
  • A lane alias (flux-fast, flux-standard, flux-reasoning) to target a speed and capability lane and its rate.
  • A flux-pinned-* id when you want a specific backing model every time. Find the id on Models or list them with GET https://api.fluxrouter.ai/v1/models.

What each option costs is on Pricing. For a side-by-side of the two gateways, see Flux vs OpenRouter.

What stays the same

  • The OpenAI SDK and its method names.
  • The endpoints: /v1/chat/completions, /v1/responses, /v1/models.
  • Auth header style: Authorization: Bearer sk-....
  • The request and response JSON, including streaming, tool calls, and structured outputs.

Before you switch production traffic

Run these checks with the new key before real traffic moves.

  1. List models. GET https://api.fluxrouter.ai/v1/models proves the key works and shows the ids you can use.
  2. Send one non-streaming call and read the headers. You should see the receipt headers from Receipts, including X-Flux-Cost-Usd. A streamed response has no cost header.
  3. Send one streaming call. Check that your chunk parsing holds to the end of the stream.
  4. Run one tool-call round trip with your real tool schema. If tools are essential to your product, test the pinned model you will rely on as well as flux-auto, because tool support belongs to the model that answers.
  5. Check any pin. Send your flux-pinned-* id without streaming and read X-Flux-Routed: false and X-Flux-Model.
  6. Log X-Flux-Request-Id from day one. It is the first thing support asks for.
  7. Canary first. Set a prepaid daily or monthly cap in Billing (see Spend caps), send a slice of traffic, compare errors, latency and cost with your OpenRouter baseline, and keep the old key until a full day runs clean. The old key is your rollback.

Next steps