Frequently asked questions
Answers about accounts, networks, payment ceilings, free answers, API keys, receipts and MCP.
Questions and answers
Do I need an account?
- Not for direct x402 calls to SingIt Ask. You pay with USDC from your own wallet. API keys are optional and are created in the SingIt app.
Which networks can I use?
- Base and Solana use the same Ask URL. Chat payment challenges offer upto and exact on both networks.
What does upto mean?
- You sign a maximum amount for one request. Only actual model cost + 30% + the network settlement fee is charged, within that ceiling.
Why did I get 402 again?
- A request may still need payment or a fresh permit. Read the error code and PAYMENT-REQUIRED header. A settlement-failure 402 has no challenge header; reconcile the submitted payment before retrying.
Am I charged on failure?
- No billable answer means no settlement. A 503 never charges. A 409 for a reused signature makes no new charge; check the original request result.
How can I try it free, and what are the limits?
- Choose from 6 free models, for example free/deepseek-v4.1-flash, without a wallet or key. Defaults are 20 answers per visitor network per UTC day, 400 output tokens and 4000 question characters. A shared $0.25 daily cost cap and concurrency limit also apply. The shared free tier may run out for the day (free_budget_exhausted); it resets at midnight UTC. See Limits.
How are prices shown against list price?
- The model pages show SingIt prices alongside model list prices. The model-cost component adds 30%; x402 model answers also include a settlement fee of 0.001 USDC on Base or 0.002 on Solana. An upto ceiling is authorization, not the final charge.
Where are the receipts?
- Read billing.totalAtomic in the answer and the PAYMENT-RESPONSE and X-SingIt-Receipt response headers. The receipt distinguishes the authorized ceiling from the settled amount.
How do I get an API key?
- Open the SingIt app, go to API keys and have your wallet sign the key’s daily limit, per-request limit and expiry.
Can I use MCP?
- SingIt provides a remote MCP server for free lookups and paid tools; see Developers.
6 free models, up to 20 answers a day per network, with a shared daily cost cap of $0.25. The shared free tier may run out for the day (free_budget_exhausted); it resets at midnight UTC. Example: free/deepseek-v4.1-flash.