Acceptable use

Browse as much as you like. Look things up, share a link, print a page, tell somebody where the nearest post office is. That is what it is for and there is no limit on it.

The API is free and needs no key. It is meant for personal and small-scale use: a hobby project, a prototype, a page of your own that looks something up. As a rule of thumb, keep to around 1,000 requests a month from any one address. That is a guide rather than a meter today, and we would rather it stayed that way.

If you need more than that, write to us and say what you are building. We are far more likely to help than to object, and splitting a large job across several addresses to stay under a guideline is a breach of this policy rather than a clever solution to it.

Two practical things that keep you well inside it: debounce a typeahead by at least 150 milliseconds, and cache the postcode index rather than fetching it per keystroke. Responses are cacheable at the edge and a well-behaved client costs almost nothing.

Search engine crawlers are welcome, and nothing here is designed to stop them: any limit we ever apply is on the API, never on reading the site. Other automated collection is a different matter. Do not crawl the site to extract its contents in bulk, do not scrape pages as a substitute for the API, and do not use headless browsers to work around a guideline.

If you want the underlying data, take it from the source rather than from us. Most of it is OpenStreetMap, which publishes complete extracts freely and would rather you used those. The sources page says where each dataset comes from.

• Rebuild this directory somewhere else from its pages, or pass its content off as your own.
• Strip the attribution that the data licences require when you republish anything taken from here.
• Use the site or the API to send unsolicited messages, to harvest contact details, or to build a list of anything for marketing.
• Attempt to gain access to any part of the system you were not given, probe it for weaknesses without asking first, or interfere with its operation for anyone else.
• Present the information here as authoritative to somebody who will act on it without checking, in a way that could cost them something.

If you have found something that looks like a vulnerability, we would genuinely like to know. Write to postmaster [at] postfinder.io with enough detail to reproduce it and give us a reasonable chance to fix it before you publish. Testing that stays within a single account of your own and does not degrade the site for anybody else will not be treated as a breach of this policy.

Requests get refused, and access may be withdrawn from an address or a network. Where something is causing harm we will act first and explain afterwards. We would much rather have the conversation: contact us and tell us what you need.