Free $10 of Opus 5 API credit, valid for 24 hours.

How to use it

Three steps. Copy, paste, run.

1. Clear any old Anthropic key first

   ANTHROPIC_API_KEY takes priority over the token below. If you have ever configured a direct Anthropic key, leaving it set is the single most common failure: you paste our key and still get errors about your Anthropic account.

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   # reports presence only, never prints the value
   test -n "$ANTHROPIC_API_KEY" && echo "found ANTHROPIC_API_KEY - unset it"
   unset ANTHROPIC_API_KEY

2. Set three variables

   The base URL has no /v1 suffix — Claude Code appends /v1/messages itself. Use ANTHROPIC_AUTH_TOKEN, which is sent as a Bearer token, not ANTHROPIC_API_KEY.

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   export ANTHROPIC_BASE_URL=https://api.sharkflow.top      # no trailing /v1
   export ANTHROPIC_AUTH_TOKEN=<your key>         # not ANTHROPIC_API_KEY
   export ANTHROPIC_MODEL=free-opus          # the only model we publish

3. Run Claude Code

   That is the whole setup. Ask it something to confirm the route works.

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   claude

   Prefer a raw request? This one-liner is the smallest end-to-end check. Confirm the response body is JSON — a 200 carrying HTML means the base URL is wrong, not that it worked.

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   curl -s -X POST "$ANTHROPIC_BASE_URL/v1/messages" \
     -H "content-type: application/json" \
     -H "authorization: Bearer $ANTHROPIC_AUTH_TOKEN" \
     -H "anthropic-version: 2023-06-01" \
     -d '{"model":"free-opus","max_tokens":16,
          "messages":[{"role":"user","content":"reply with just: ok"}]}'

If something breaks

Four symptoms cover almost every report.

FAQ

The questions people actually ask before pasting a key.

Why is this free?

It is free trial credit and a customer-acquisition cost on our side. We would rather pay for you to try the endpoint on real work than pay for an ad you scroll past. There is no upsell attached to the key and nothing to cancel — when the 24 hours end, it simply stops.

Do I really not need an account?

Correct. No signup, no email, no OAuth, no card. You claim a key and use it. The only limit is the number of keys we hand out per day, so keys can run out before the day does.

How are the 24 hours counted?

As a rolling 24 hours from the moment you claim the key — not until midnight in some timezone. Claim at 21:40 and the key works until 21:40 the next day. So claim it when you have time to use it.

Will I always be served by Opus 5?

Usually, but not guaranteed. During peak load our endpoint may automatically fall back to a different backing model, and the model name you configured does not change when that happens. We are telling you up front because otherwise you might judge Opus 5 by output that did not come from it.

If a response feels off-character for Opus, that fallback is the most likely explanation. Retrying a few minutes later usually lands you back on the primary model.

Which protocol does the endpoint speak?

Anthropic-native /v1/messages, plus an OpenAI-compatible surface under https://api.sharkflow.top/v1. Streaming works. Tool calling is best supported on the Anthropic-native path, so prefer that one for agent-style clients.

What happens to my prompts?

Requests are proxied to a model backend to answer them, the same as any API gateway. Do not send secrets, customer data, or anything you would not put through a third-party endpoint — that is good practice with any trial credit, ours included.

Take the credit

One click, then three lines in your terminal.

Get your key

No signup required. Daily keys are limited and may run out.