Free tools for AI agents: no signup, no API key

The solution

curl -X POST https://api.strale.io/v1/do \
  -H "Content-Type: application/json" \
  -d '{
    "capability_slug": "iban-validate",
    "inputs": { "iban": "DE89370400440532013000" }
  }'
# No API key and no wallet.

The tools that are free today

Bitcoin Address Validation, DNS Lookup, Dogecoin Address Validation, Email Validation, Ethereum Address Validation, IBAN Validation, JSON Repair, Solana Address Validation, Tron Address Validation, URL to Markdown and XRP Address Validation.

The list is read from the catalogue each time the site is built. It changes as tools are added, so treat the Tools page, or GET /v1/platform/facts, as the source of truth.

Why these tools are free

They are algorithmic or protocol-level checks, such as format validation, DNS lookups, JSON repair and address-format checks, with little or no metered upstream cost for each call. Tools that call a paid source, such as a register, a screening vendor or a language model, are not on the list.

The allowance, precisely

Anonymous callers get 300 calls per calendar month (UTC) per IP address, counted in a database, so retries and different user agents do not reset it. The allowance is shared by every free tool, not set per tool, and an hourly guard stops bursts. Each anonymous free-tool response carries X-RateLimit-* headers and a usage block with calls_this_month, monthly_limit and resets_at.

With an API key, free tools get the normal limits and cost nothing. Paid tools need a funded wallet, or an x402 payment with no signup on the tools that accept it: see x402.

Limits

• The allowance is per IP address, not per user. An office network, shared Wi-Fi or a CI runner behind one address shares one allowance.
• The list can change. Tools move on and off the free list as the catalogue changes.

Questions

Do free calls get a record?

Yes. Every call, with a key or without, returns a transaction_id and the source of the data. With a key, free calls also appear in your list of calls.

Can I go past the allowance without paying?

Signing up is free, and a key moves you from the per-IP monthly allowance to the normal limits on the same free tools. Free tools stay free.

Is this a sandbox with fake data?

No. These are the production endpoints with real results. The only differences are the allowance and that no key is needed.

Tools in this guide