Migrate from OpenAI to Railwail in 2 Minutes

OpenAI's API is excellent — but it locks you into a single vendor. When GPT-4o costs spike or a competitor releases a better model, you cannot switch without rewriting integration code. Railwail solves this by exposing major frontier models behind the OpenAI-compatible Chat Completions schema. You get the OpenAI developer experience plus the freedom to swap providers with a single string change.

In addition to portability, teams move to Railwail for the ability to test Claude, Gemini, Llama, DeepSeek and 200+ more models without managing separate accounts. This guide walks through the full migration end to end.

Sign up at railwail.com, go to Dashboard → API Keys, and click Create New Key. Keys are prefixed with rw_live_ and look like rw_live_xxxxxxxxxxxxxxxxxxxxxxxx. Sign up with Google to get 10 free credits ($0.10), usable 24 hours after sign-up.

Copy the key into your environment file. The convention in most projects is to keep the existing OPENAI_API_KEY name so you do not have to touch your config-loading code — Railwail keys work in that variable transparently because the SDK does not validate the prefix.

import OpenAI from "openai";

const openai = new OpenAI({
  apiKey: process.env.OPENAI_API_KEY,
});

const res = await openai.chat.completions.create({
  model: "gpt-4o",
  messages: [{ role: "user", content: "Hello" }],
});

import OpenAI from "openai";

const openai = new OpenAI({
  apiKey: process.env.RAILWAIL_API_KEY,
  baseURL: "https://railwail.com/api/v1",
});

const res = await openai.chat.completions.create({
  model: "gpt-4o",
  messages: [{ role: "user", content: "Hello" }],
});

from openai import OpenAI

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

resp = client.chat.completions.create(
    model="gpt-4o",
    messages=[{"role": "user", "content": "Hello"}],
)
print(resp.choices[0].message.content)

curl https://railwail.com/api/v1/chat/completions \
  -H "Authorization: Bearer $RAILWAIL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-4o",
    "messages": [{"role": "user", "content": "Hello"}],
    "stream": false
  }'

Run your existing test suite. Because Railwail proxies the upstream OpenAI API directly when you call OpenAI model IDs, streaming SSE chunks, function/tool-call deltas, vision messages with image_url, and the response_format JSON mode all behave identically.

This is where the migration starts paying off. With the same SDK and the same client object, you can route a request to Claude or Gemini just by changing the model string. There is no second SDK to install, no second API key, no separate billing.

// Same client, different model
const claude = await openai.chat.completions.create({
  model: "claude-sonnet-4-6",
  messages: [{ role: "user", content: "Hello from Claude" }],
});

const gemini = await openai.chat.completions.create({
  model: "gemini-2.5-pro",
  messages: [{ role: "user", content: "Hello from Gemini" }],
});

You only need to change the model string if you want to try a different provider — and even then, you can keep the OpenAI SDK.

• 200+ models behind one API key — Claude, Gemini, DeepSeek, Flux
• Single SDK — keep the OpenAI client your team already knows
• Built-in playground at railwail.com/models — test any model before shipping
• Spend caps and per-key rate limits to prevent runaway bills
• Transparent per-token pricing — no minimum monthly fees, no enterprise gating

• Create your free account at railwail.com
• Generate an API key in Dashboard → API Keys
• Change two values in your code: baseURL and apiKey
• Read the full API reference at railwail.com/docs
• Browse all 200+ available models at railwail.com/models
• Compare per-token pricing at railwail.com/pricing
• Check the provider catalog at railwail.com/providers