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Claude Opus 5.5 is live →

One key for frontier models

OpenAI- and Anthropic-compatible. Business accounts, usage-based, settled offline.

Explore models →Read the docs
POST /v1/messages
curl https://api.modelrail.cc/v1/messages \
  -H "x-api-key: $MODELRAIL_KEY" \
  -d '{
    "model": "claude-sonnet-4-6",
    "max_tokens": 1024,
    "messages": [{ "role": "user", …}]
  }'
Single requestSettled
claude-sonnet-4-6
Input1,842 tok
Cached12,288 tok
Output612 tok
Cost$0.018392
Credit left$4,981.63

Native access

Served through official cloud channels, with native Anthropic and OpenAI responses.

Visible cost

Every request is itemized; input, cached input and output are billed separately.

One integration

One key reaches every listed model. No extra vendors or credentials.

Business billing

Priced in USD, settled offline under contract. Requests stop the moment credit runs out.

Models

All models →
Claude Opus 5.5
claude-opus-5-5
$4 Input$0.2 Cached$20 Output1,000K Context
Claude Opus 4.6
claude-opus-4-6
$5 Input$0.5 Cached$25 Output1,000K Context
Claude Sonnet 4.6
claude-sonnet-4-6
$3 Input$0.3 Cached$15 Output1,000K Context

Get started in three steps

  1. 01

    Open an account

    Contact us to set up your org; admins can invite teammates.

  2. 02

    Create an API key

    In the console or the CLI, with an optional spend limit.

  3. 03

    Integrate

    Point your base URL at ours. Nothing else changes.

Ready to integrate?

Business accounts are usually live the same day. Then it is one line: your base URL.

Read the docshttps://api.modelrail.cc