Migrate from OpenRouter

/v1/chat/completions, /v1/completions, /v1/models, /v1/key, /v1/credits and /v1/generation answer in OpenRouter's shapes, under OpenRouter's field names. For most integrations the migration is two lines. Everything this gateway adds is additive (extra keys on the same objects), so a client that ignores what it does not recognise will never see them.

Identical, and needs no edit

• The request body of /v1/chat/completions and /v1/completions, including models, stream, tools, response_format, provider routing and every sampling parameter.
• The streaming framing: data: {…} frames, terminated by data: [DONE].
• usage, with prompt_tokens, completion_tokens and total_tokens.
• The Authorization: Bearer header, and unknown body fields being forwarded upstream rather than refused.
• The request and response of /v1/responses, /v1/embeddings, /v1/images, /v1/videos, /v1/audio/speech, /v1/audio/transcriptions and /v1/rerank.

Route map

The base URL

https://openrouter.ai/api/v1 becomes https://api.routehook.ai/v1. The /api segment goes and the /v1 stays. An OpenAI client appends the route to whatever base URL it is given, so that is the string it wants verbatim. An Anthropic client is the one exception, and /docs/sdks says what it wants instead.

The key

An OpenRouter key is sk-or-v1-…; here it is sk_live_…. The header does not change. There is no test key and no sandbox (every key spends the balance), so cap what a new one may spend and read GET /v1/key to assert which key a deploy picked up, rather than finding out from an invoice.

Attribution headers

HTTP-Referer and X-Title do not have to be removed. HTTP-Referer is recorded as origin on the request record and comes back on GET /v1/generation. X-Title is accepted and then ignored. There is no public application leaderboard here to be ranked on, so the header has nowhere to go.

Model ids

Slugs are vendor/model, and many are spelt exactly as OpenRouter spells them, but they are this catalogue's ids, not a mirror of theirs. Resolve every id you send today against GET /v1/models before cutting over. An id that does not exist here answers 409 model_unavailable, which is a clean failure rather than a silent substitution.

Variant suffixes

Fallback models

OpenRouter's models array is here and behaves the same way: up to eight alternatives, tried in order, and only once every attempt at the preceding model has been exhausted. It changes which *model* answers, which is the caller's decision and never the operator's, so nothing is tried unless you send it.

The configured circuit breaker still removes unhealthy targets automatically. Your block is applied on top: only and ignore narrow the chain, order and sort reorder it, allow_fallbacks: false pins the first eligible target, and require_parameters removes targets that cannot honour fields in this request.

Before

import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://openrouter.ai/api/v1",
  apiKey: process.env.OPENROUTER_API_KEY,
  defaultHeaders: {
    "HTTP-Referer": "https://your.app",
    "X-Title": "Your App",
  },
});

const completion = await client.chat.completions.create({
  model: "openai/gpt-4o-mini",
  models: ["anthropic/claude-sonnet-4"],
  provider: { sort: "throughput" },
  messages: [{ role: "user", content: "Hello" }],
});

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

After

import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://api.routehook.ai/v1",
  apiKey: process.env.ROUTEHOOK_API_KEY,
  defaultHeaders: {
    "HTTP-Referer": "https://your.app",
    "X-Title": "Your App",
  },
});

const completion = await client.chat.completions.create({
  model: "openai/gpt-4o-mini",
  models: ["anthropic/claude-sonnet-4"],
  messages: [{ role: "user", content: "Hello" }],
});

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

What is not here

• No key provisioning. There is no /keys API and no OAuth exchange. Keys are created in the dashboard, and is_provisioning_key on GET /v1/key is always false.
• No per-key model allowances. Every key reaches the whole catalogue, so there is no filtered model list to migrate and nothing to grant.
• No free tier. is_free_tier is always false, and a :free id resolves to no model at all.
• Transforms and plugins are not implemented yet. A non-empty request is rejected explicitly instead of being silently changed. Trim long prompts yourself and remove plugin configuration before migrating.
• No bring-your-own-key. There is no route to attach your own upstream credentials and be billed by that vendor instead of by us.

What you gain

• POST /v1/embeddings and POST /v1/images/generations, neither of which OpenRouter serves.
• POST /v1/messages, so an Anthropic client reaches the same account and the same balance.
• The queue (POST /v1/queue/{model} and the routes that follow it) for video and anything else that outlives an HTTP request.
• POST /v1/mcp: the catalogue, the gateway and the queue as MCP tools.
• reference_value on every generation record. What the same call costs at the vendor's list price, measured per request rather than asserted per month.

Cutting over

1. 01
   Issue a key for the migration

   Give the cutover its own key with a spend cap, rather than reusing one already in production. It is obvious in a log, cheap to revoke, and the cap bounds what a mistranslated request can cost while you are still checking the mapping.

2. 02
   Resolve every model id

   Read GET /v1/models and map each id your code sends today onto a slug that exists here. This is the only step that cannot be automated, and the only one that fails at runtime if it is skipped.

3. 03
   Point one environment at the new base URL

   Change the two lines and deploy staging. The provider block, models array and streaming loop carry over unedited; remove plugins and transforms until those execution layers are available.

4. 04
   Reconcile a handful of requests

   Take the X-Routehook-Request-Id from a few responses and read GET /v1/generation?id=req_…. Compare usage against what you were paying and reference_value against the vendor's own list price.

5. 05
   Swap the live key, then revoke the old one

   In that order. Revocation on either side takes effect immediately, so doing it the other way round takes the integration down for the length of a deploy.

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