Last updated: 9 July 2026
These terms govern the Linguin API, offered by Surfy Ltd, a company registered in England and Wales (company number 15026168), registered office at 14-2e Docklands Business Centre, 10-16 Tiller Road, London, E14 8PX, United Kingdom. They apply together with the Terms of Service. By creating an API key or calling the API you accept both.
Access is by bearer key. A key is shown in full once, at creation, and stored hashed on our side, so treat it like a password. Every call made with your key is your call, whoever made it. If a key leaks, revoke it on your API page and mint a new one. Test keys and live keys are separate, and only live keys spend money.
The API is prepaid. You top up a balance, and each billable call deducts its cost at the rates on the API pricing page, which is the authoritative price list. Every priced response carries its own cost, and your billing page shows the full statement.
The essentials of how billing behaves:
You can withdraw the unspent part of your balance at any time, self-service, from your billing page. What comes back is the money you actually paid in, net of what you spent, returned to the cards that paid it. Promotional credit, including the welcome credit, is spendable on calls but is never paid out as cash.
Calls are rate-limited per client. The default limit is generous for normal integration and stated in the documentation. Do not use the API to reconstruct, resell, or redistribute the dictionary as a dataset, and do not probe, overload, or circumvent the gateway. Output belongs in your product: translations are yours to use freely, and dictionary results may be shown to your users but not accumulated into a competing corpus.
Text you send us is processed to serve the call and logged with the request so you can retrieve results and audit your usage. For your end users' personal data you are the controller and we are your processor: send us only what you are entitled to send, and we will process it only to serve your calls. The Data Processing Addendum is part of these terms and governs that processing. If you need a countersigned copy, ask on the contacts page.
Synchronous calls return the result directly. Webhook delivery is attempted once, and fetching the request by its id is the documented recovery path, free of charge. We run the API with care but sell no uptime guarantee. If we retire or change an endpoint in a breaking way, we will announce it in updates with reasonable notice, and API versioning keeps existing integrations working in the meantime.
We can suspend keys or clients that break these terms, threaten the service, or process data unlawfully. Where reasonable we warn first. Your balance stays refundable under the rules above even if access is suspended, unless the law says otherwise.
The API and its output are provided as is. Generated content can be wrong, and you are responsible for how your product uses it downstream. Our total liability under these terms is limited to the amount you paid for the API in the twelve months before the claim. Nothing here limits liability that cannot be limited by law.
These terms are governed by the law of England and Wales, and its courts have jurisdiction.