Anthropic-Compatible Messages API
OpenPaths speaks the Anthropic Messages protocol, so the official Anthropic SDKs and agent frameworks work by changing the base URL. Claude models are billed at provider rates.
Anthropic Messages API models and pricing
| Model | Provider | Context | Price |
|---|---|---|---|
Claude Fable 5.1 claude-fable-5-1 | Anthropic | 1M | $10.00 in / $50.00 out per 1M tokens |
Claude Fable 5 claude-fable-5 | Anthropic | 1M | $10.00 in / $50.00 out per 1M tokens |
Claude Opus 5.5 claude-opus-5-5 | Anthropic | 1M | $4.00 in / $20.00 out per 1M tokens |
Claude Opus 5 claude-opus-5 | Anthropic | 1M | $5.00 in / $25.00 out per 1M tokens |
Claude Opus 4.8 claude-opus-4-8 | Anthropic | 1M | $5.00 in / $25.00 out per 1M tokens |
Claude Opus 4.7 claude-opus-4-7 | Anthropic | 200K | $5.00 in / $25.00 out per 1M tokens |
Claude Sonnet 5.5 claude-sonnet-5-5 | Anthropic | 1M | $2.00 in / $10.00 out per 1M tokens |
Claude Sonnet 5 claude-sonnet-5 | Anthropic | 1M | $2.00 in / $10.00 out per 1M tokens |
Claude Haiku 5.5 claude-haiku-5-5 | Anthropic | 1M | $0.10 in / $0.50 out per 1M tokens |
Claude Opus 4.6 claude-opus-4-6 | Anthropic | 200K | $5.00 in / $25.00 out per 1M tokens |
Claude Haiku 4.5 claude-haiku-4-5-20251001 | Anthropic | 200K | $1.00 in / $5.00 out per 1M tokens |
Claude Opus 4.5 claude-opus-4-5-20251101 | Anthropic | 200K | $5.00 in / $25.00 out per 1M tokens |
Claude Sonnet 4.5 claude-sonnet-4-5-20250929 | Anthropic | 200K | $3.00 in / $15.00 out per 1M tokens |
FAQ
Which auth header do I use?
Either x-api-key (Anthropic style) or Authorization: Bearer; both accept your OpenPaths key.
How do I get an API key?
Create an account and your first key is issued immediately. The same key works for every model and endpoint on OpenPaths.
How is it priced?
Prepaid, pay-as-you-go credits at close to provider list price with no subscription. The tables on this page are generated from the live OpenPaths model catalog.