AIMS Address API: The Automated Information Mapping System (AIMS) is provided by Johnson County, Kansas. It can be used by individuals, government organizations or businesses looking for a GIS solution. AIMS offers services including map production, custom enterprise-level application development, and data development. The Address Web Service allows developers to search, validate and geocode against the Johnson County master address database. If a user finds an address, they can also lookup the tax property ID and its tax unit. Methods are including to give users all the valid cities, zip codes, street types, street directions, unit designators, and street names used in the county. The API uses SOAP protocol and responses are formatted in XML.
Intech IQ Hosted API: Intech is a provider of information quality software for businesses of all sizes. Their IQ Office suite is a solution to help with information transformation, validation, standardisation, matching and integration of a wide array of data sources, both in batch mode as well as in real-time at the point of data capture.
As part of the IQ Office suite, the IQ Hosted Web Service is a web based address validation and geographic coding solution used for cleaning addresses and adding geographic information. The API uses SOAP protocol and responses are formatted in XML. Full documentation is available to customers.
IP-API.com Geolocation API: IP-API.com is a website that allows users to lookup the location of an IP address. The site provides free usage of its geolocation API and supports IPv4/IPv6 queries. The API allows users to supply an IP address or domain to lookup, or none to use their current IP address. Data returned includes country, region/state, city, zip code, latitude, longitude and more. The API uses RESTful calls and responses can be formatted in XML, JSON, CSV, Newline Separated and PHP.
OpenCaching API: The OpenCaching API gives users the ability to query all of the data stored in the OpenCaching.com database. The service can also authorize users to update and write to the database. The API uses REST calls and will return JSON, XML, or plain text depending on which data request is sent. The OpenCaching service is a community based geocaching service with user generated content. The site is a subsidiary of Garmin Ltd.
And a bonus API:
MapQuest has officially released the first production version of the iOS Maps API as of July 19 (MapQuest Blog)
