Evaluate Claude API cost without rewriting your client
A focused guide for developers comparing Claude API access, compatibility, and total cost. Price matters alongside limits, reliability, and data-handling requirements.
Anthropic-compatible Messages API
Send Claude-style requests to the familiar /v1/messages endpoint. Keep your existing x-api-key, anthropic-version, model, and message fields while choosing an available model from the live catalog.
curl https://relay.fast/v1/messages \
-H "x-api-key: sk-your-api-key" \
-H "anthropic-version: 2023-06-01" \
-H "Content-Type: application/json" \
-d '{"model":"claude-sonnet-5-5","max_tokens":64,"messages":[{"role":"user","content":"Reply with OK"}]}'What to verify before switching
- Confirm the exact model identifier and current token pricing in the live catalog.
- Test streaming, tool use, image inputs, and context limits with your own workload.
- Review retention, support, rate limits, and refund terms before sending sensitive data.
Make the comparison measurable
cheap Claude API guide pairs a compatible endpoint with a checklist for model IDs, streaming, tools, context size, and error behavior. Run a representative prompt set and record input/output tokens, latency, retries, and successful completions.
live pricing catalog shows the current catalog. service status helps you separate a temporary incident from a pricing or integration issue.
Current Claude model prices
Prices checked from the live catalog. "From" is the lowest price among the relay.fast sources that currently serve the model. The price you pay depends on the source your request uses and can change on any day. The pricing page always shows current values.
| Model | Model ID | Official input / output per 1M tokens | relay.fast from, input / output | Cache read from | Context |
|---|---|---|---|---|---|
| Claude Fable 5.1 | claude-fable-5-1 | $10 / $50 | $2.23 / $11.16 (−77%) | $0.0558 | 1M |
| Claude Opus 5.5 | claude-opus-5-5 | $4 / $20 | $0.111 / $0.556 (−97%) | $0.00556 | 1M |
| Claude Sonnet 5.5 | claude-sonnet-5-5 | $2 / $10 | $0.238 / $1.19 (−88%) | $0.0238 | 1M |
| Claude Haiku 5.5 requests above 100K input tokens cost more | claude-haiku-5-5 | $0.1 / $0.5 | $0.0223 / $0.112 (−77%) | $0.00223 | 1M |
| Claude Opus 4.8 | claude-opus-4-8 | $5 / $25 | $0.139 / $0.694 (−97%) | $0.0139 | 1M |
Frequently asked questions
Does this replace an Anthropic account?
It is a separate gateway account and key. Your application talks to relay.fast, which then routes the request to an available configured provider channel.
Can I use the Anthropic SDK?
Yes. Set the SDK base URL and authentication according to the Anthropic-compatible example, then use a model currently listed for your account.
Is a shared or free key provided?
No. Use your own relay.fast account and key. Avoid shared credentials because they are unsafe and make usage, limits, and revocation ambiguous.