Not everywhere has postal codes, please do not require them.

Love,

People-in-Ireland-tired-of-typing-fake-postal-codes

In theory, with an api like this you could easily figure that out and then customize the fields as needed.

This. I lived in Hong Kong briefly and always had to fake the postal code if accessing an outside website.

I wrote a gem for postal/area codes in the US that does mostly the same thing w/o the web request http://github.com/jgv/area

Looks good. Just like ziptastic and all the others, but with international support. That's a real advantage.

I've always wanted to use such a library for my checkout forms and whatnot, but unfortunately it doesn't fit the typical UI paradigm.

If you need the address info, you'll (almost) never ask for the zip code before the city and state, so the information has already been filled in before the user gets that far... and the country comes last.

Users are used to entering the address info in that natural order: street, city, state, zip, country (usually pre-set to your biggest userbase). I think the cognitive overhead of mixing that order up actually exceeds the effort of having them fill in all 3 fields.

The only place I could see you using something like this is if your are tailoring your services to a US-only userbase (so you can guarantee that a zip code is there and that the other info will not need to be manually entered). For example, we use ziptastic (at the server side for cross-domain reasons) at http://gastomorrow.com/ which is a US-only service to guess the price of gas tomorrow in your area.

At least one user, me, is tired of your "typical UI paradigm" and tired of entering redundant information. 1. Ask for country (if not known) allow user to override if it was automatically detected. 2. Ask for zip, or other country specific postal code. 3. Look up zip. Fill form in with details.

Many UK sites will start by asking for a postcode, which then lets them offer a drop-down of usually less than a dozen properties to fill in the rest of the address, guaranteed to be in standardised form.

The databases aren't always as complete as the developers believe them to be though -- sensible operators will leave a way to override the lookup, others lose out on custom from people living in new estates.

The solution is to ask for the zip code immediately after the street name. I work on insurance software and several of our applications do this.

We do support reverse city+state to zip lookup and lookup nearby zips for USA aswell

I find this very interesting, just being now into internationalizing a site of my own which requires specially this. One question for UK residents: is lack of "out codes" a problem?

Also, to the author(s) of zippopotam.us, if they're reading: - How can we trust you're not going away any time soon? I don't see any pricing, so I assume this is all free? - Related to the first point, I assume you don't want to be used by any high traffic site, since you probably don't have a lot of server power behind this. What's the plan?

What are you trying to do with the UK postal codes?

Address lookup or just validation?

For validation, there's an official regex (archived, but still useful) http://www.cabinetoffice.gov.uk/govtalk/schemasstandards/e-g....

For address lookup there are a couple of ways to go about it.

1. You can buy the rights to the Royal Mail's database. You get to parse the sucker yourself. http://www.poweredbypaf.com/end-user/products/paf-raw-data/

2. You can use a third party system, either over the web, or choose a solution you can host internally. Depending on the type of system you buy you pay by the lookup or by the user (mostly internally hosted systems).

You can get postcode/easting/northing for free using Ordnance Survey's Code-Point Open product [1]. That'll let you check a postcode exists, but it doesn't help with address auto-completion, as it doesn't give you a street name.

[1] http://www.ordnancesurvey.co.uk/oswebsite/products/code-poin...

> "How can we trust you're not going away any time soon?"

We are hosted on DotCloud(YCS10) - and thanks to generous agreement with them, we have a very large free plan and until we have issues managing demand, we don't plan to ask for donations.

Several well known sites us zippopotam.us such as TheNounProject and Pocket.

There are several alternatives to us and if don't trust us, don't use us - our intention is to serve sites that can't be bothered to download dbs and serve the codes themselves.

For Slovakia, the db doesn't seem to be complete. When I was looking for some source, I've found one one that has almost the same number of rows and also misses the ones I tried to find. There was also packed a db that is more complete and it might be a great idea to process and use that one. Both can be found here: http://www.posta.sk/subory/322/psc-obci-a-ulic.zip (zip contains 2 xml files)

In case your intention is to contribute zip codes, please go through the github repository https://github.com/crowell/zippopotamus

I currently use Geonames to map ZIP codes to locality names, and find nearby ZIP codes/localities given a ZIP code. Can you explain why your service is preferable for me?

Not every website wants to go through the effort of collecting zip codes. We used geonames as our primary seed and its a great source but it isn't free.

Thank you to whomever did this. I'm always annoyed by any form that wants my zip and city and state. Why? Once you have the zip, then you have the city and state.

Some zip codes have more than one municipality within them.

For example: https://tools.usps.com/go/ZipLookupResultsAction!input.actio...

The Cupertino zip code (95014) also brings up Monta Vista and Permanente, but I've never seen these two "cities" on a map nor met anyone who claims to be from there. I don't know if this is some artifact in the USPS database or they know something I don't.

If anyone is interested in developing a similar service, then you can use the (free) zip code information provided by the US Census Bureau:

http://www.census.gov/geo/www/tiger/zip1999.html

However, please note that some information may be outdated. The US Postal Service now maintains the zip code data sources, but I'm not sure if you must pay for it.

UK post codes are two part, something like A1 1AA. A1 identifies a geographic area, 1AA identifies a set of postal address in that area (its designed so each post code gets roughly the same amount of mail, so big organisations have an address to themselves).

Zippopotam.us only seems to deal with the first part, which is only of marginal utility.

The JavaScript example uses CORS, which doesn't have universal browser support. (Older Opera, Old IE: http://caniuse.com/cors)

Any reason there isn't JSONP support?

Spelling mistake in the header of the country-specific pages: Zippoptamus (e.g. http://www.zippopotam.us/static/sample_us.html)

best name ever :)

Thanks, Mate.