Claude API proxy: a relay with its own balance
A Claude API proxy is a server between your client and the Claude models. Most of the ones on GitHub translate request formats on your own machine and bill whatever Anthropic account sits behind them. RelaySwitch is the other kind: a hosted relay with its own balance, where 13 Claude ids answer Anthropic's Messages format on a prepaid key, topped up by card or in USDT, USDC, BTC, ETH, SOL.
Format translators and hosted relays
The phrase covers two different programs. Pick by what sits behind the proxy.
A translation proxy on GitHub
- Runs on localhost. Takes one request shape in and sends another out: OpenAI chat completions to Anthropic Messages, or the Claude Code CLI wrapped as an HTTP API.
- Has no models and no balance. Every request is billed by the account behind it: an Anthropic API key, or a Pro or Max subscription.
- Rate limits are the account's own, and a wrapped subscription cannot report them in response headers.
A hosted relay with its own balance
- An endpoint on the internet. The Claude ids answer the Messages format unchanged at
https://api.relayswitch.io/v1/messages, and the OpenAI format on the same key. - One prepaid balance in USD, per-token billing at the rates below, a key per app with its own budget. No Anthropic account.
- A signed receipt per request and a public daily check that the id answers as it did yesterday.
Anthropic SDK and Claude Code
Two values change: the base URL becomes https://api.relayswitch.io/v1 and the key becomes yours. The request body is Anthropic's.
Python, with the Anthropic SDK
import anthropic client = anthropic.Anthropic(base_url="https://api.relayswitch.io/v1", api_key="sk-relay-...")reply = client.messages.create( model="claude-sonnet-5-5", max_tokens=300, messages=[{"role": "user", "content": "Hello"}],)print(reply.content[0].text)Claude Code
export ANTHROPIC_BASE_URL="https://api.relayswitch.io/v1"export ANTHROPIC_AUTH_TOKEN="sk-relay-..."claudeANTHROPIC_BASE_URL sets the endpoint and ANTHROPIC_AUTH_TOKEN sends the key as a Bearer token, per Claude Code's environment variable reference (read 2026-10-30). The Claude Code guide has the settings.json form, the model aliases and a key with a budget for Claude Code alone.
The same request as curl
curl -i https://api.relayswitch.io/v1/messages \ -H "Authorization: Bearer $RELAYSWITCH_API_KEY" \ -H "anthropic-version: 2023-06-01" \ -H "content-type: application/json" \ -d '{"model": "claude-sonnet-5-5", "max_tokens": 16, "messages": [{"role": "user", "content": "Say ok."}]}'The Claude ids behind the relay
USD per million tokens, read from the catalog at render. Anthropic's list price beside ours on every row.
| Model | Input | Cached | Output | Developer list in / out | Context |
|---|---|---|---|---|---|
| Claude Fable 5.1 | $6.00 (40% under) | $2.00 | $30.00 (40% under) | $10.00 / $50.00 | 1M tokens |
| Claude Fable 5 | $3.00 (70% under) | $0.30 | $15.00 (70% under) | $10.00 / $50.00 | 1M tokens |
| Claude Opus 5.5 | $2.80 (30% under) | $0.15 | $10.00 (50% under) | $4.00 / $20.00 | 1M tokens |
| Claude Sonnet 4.6 | $1.80 (40% under) | $0.18 | $9.00 (40% under) | $3.00 / $15.00 | 1M tokens |
| Claude Opus 4.6 | $1.80 (64% under) | $0.16 | $7.50 (70% under) | $5.00 / $25.00 | 1M tokens |
| Claude Opus 4.7 | $1.80 (64% under) | $0.16 | $7.50 (70% under) | $5.00 / $25.00 | 1M tokens |
| Claude Opus 4.8 | $1.80 (64% under) | $0.16 | $7.50 (70% under) | $5.00 / $25.00 | 1M tokens |
| Claude Opus 5 | $1.80 (64% under) | $0.16 | $7.50 (70% under) | $5.00 / $25.00 | 1M tokens |
| Claude Haiku 4.5 | $0.60 (40% under) | $0.06 | $3.00 (40% under) | $1.00 / $5.00 | 200K tokens |
| Claude Haiku 4.5 | $0.60 (40% under) | $0.06 | $3.00 (40% under) | $1.00 / $5.00 | 200K tokens |
| Claude Sonnet 5 | $1.20 (40% under) | $0.12 | $3.00 (70% under) | $2.00 / $10.00 | 1M tokens |
| Claude Sonnet 5.5 | $1.20 (40% under) | $0.075 | $3.00 (70% under) | $2.00 / $10.00 | 1M tokens |
| Claude Haiku 5.5 | $0.06 (40% under) | $0.01 | $0.15 (70% under) | $0.10 / $0.50 | 1M tokens |
13 Claude ids answer the Messages format with a developer list price on record today. Cached input is priced lower where the row supports it.
What a relay may and may not do
From Anthropic's Usage Policy, effective 2026-11-12, read 2026-10-31. Quoted, not interpreted.
The policy prohibits
- “Resell, proxy, or otherwise provide access to Claude through unauthorized means, including services that route requests through consumer subscriptions, or misrepresent the product or client being used.”
- “Intentionally bypass or interfere with capabilities, restrictions, or guardrails established within our products”, including “circumvention of the account sign-up or log-in process”.
- For consumer-facing chatbots built on any model: users must be told they are talking to an AI, at the start of each session or in the interface.
What this relay does
- Bills every request per token at the rates above, from a prepaid balance. No consumer subscription is in the path.
- Passes the Messages format through as the client sent it; the model id you name is the model the receipt names.
- Keeps no request or response bodies, as the privacy page states; one usage record per request with the model, the token counts and the charge.
- Reselling the key onward needs written approval, per the terms; the wholesale page says how to apply.
The model on the label
Two things you can check without trusting this page.
Every model in the catalog gets the same canary prompt each day and its answer is compared with the earlier runs. The verdicts are public at /proof and as JSON at https://api.relayswitch.io/v1/proof, no key needed. Today: 305 of 339 models stable, 21 changed, 13 not reached (read 2026-11-02T07:58 UTC).
Every request has a signed receipt with the model, the billed tokens and the charge. Fetch it by the request id from the response headers and check the signature on the Verify page.
curl https://api.relayswitch.io/v1/requests/REQUEST_ID/receipt \ -H "Authorization: Bearer $RELAYSWITCH_API_KEY"Claude API proxy: questions
Free proxies, GitHub, Claude Code and the Max wrappers.
The Messages format on a prepaid key
From $10 by card or in USDT, USDC, BTC, ETH, SOL. No Anthropic account, no subscription.