Models and model ids

Send a model id in the model field of any request. Ids are lowercase and exact: claude-sonnet-5-5 works, Claude Sonnet does not. One key and one balance cover every model below.

Current models

Rates are in US dollars per 1 million tokens. “Formats” says which request formats the model accepts natively: OpenAI means /v1/chat/completions (the Responses API is fully supported on GPT models only), Anthropic means /v1/messages. Click an id for the full spec sheet: context window, maximum output, modalities and plan coverage.

The same table, with filters and comparisons, is on the models page. Rates there and here come from one file, so they always match.

Free and discounted models

There are no free models at the moment. The free models page lists them when there are.

List models from code

GET /v1/models returns the models your key can call right now. It is free and does not count against any limit, so it is also the quickest way to check that a key works.

curl -s https://api.oneaiapikey.com/v1/models \
  -H "Authorization: Bearer $RELAYKIT_API_KEY"

import os
from openai import OpenAI

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

for model in client.models.list():
    print(model.id)

import OpenAI from "openai";

const client = new OpenAI({ baseURL: "https://api.oneaiapikey.com/v1", apiKey: process.env.RELAYKIT_API_KEY });

for await (const model of client.models.list()) {
  console.log(model.id);
}

The response is the OpenAI list format:

{
  "object": "list",
  "success": true,
  "data": [
    {
      "id": "claude-sonnet-5-5",
      "object": "model",
      "created": 1626777600,
      "owned_by": "…"
    }
  ]
}

The list is filtered for you:

• If the key has a model list (see per-key settings), only those models appear.
• Models that are not available to your account, or not yet priced, are left out. An account that has not paid $3 or more in total yet sees an empty list.

Anthropic-style list

Send both x-api-key and anthropic-version and the same route answers in Anthropic’s format, which is what Anthropic SDKs and Claude Code expect:

curl -s https://api.oneaiapikey.com/v1/models \
  -H "x-api-key: $RELAYKIT_API_KEY" \
  -H "anthropic-version: 2023-06-01"

# {"data":[{"id":"claude-sonnet-5-5","created_at":"…","display_name":"claude-sonnet-5-5","type":"model"}],
#  "first_id":"…","has_more":false,"last_id":"…"}

Choosing a model

• Start with a balanced model such as claude-sonnet-5-5 or gpt-5.6-terra. Move up to a flagship only when quality is the bottleneck.
• Use a fast model for sub-tasks: classification, summaries, commit messages and agent sub-steps. claude-haiku-4-5 costs a fraction of a flagship.
• Output tokens cost more than input tokens on every paid model, usually three to five times as much. Asking for shorter answers saves more than trimming the prompt.
• Long, repeated prompts (agents, RAG, chat history) get cheaper with prompt caching.

When a model id fails

All error bodies are on the errors page.