RANDOM.ORG is a true random number service that generates randomness via atmospheric noise. This page explains how to interface to the service via the Hyper-Text Transfer Protocol (HTTP). There is also the HTTP Client Archive, which contains clients that other people have written.
Important note! If you access RANDOM.ORG via an automated client, please make sure you observe the Guidelines for Automated Clients or your computer may be banned.
If you are writing a general-purpose client, please make sure it is easy for your users to run it in accordance with the guidelines.
This page contains documentation for the Integer Generator, the Sequence Generator, the String Generator and the Quota Checker, which allows you to examine your current bit allowance.
All the interfaces on this page return HTTP status code 503 (Service Unavailable) in the case of errors and code 200 (OK) when successful. Not all languages allow you to access the HTTP status codes in a straightforward manner. A reasonable workaround is to look for the string "Error:" (don't forget the colon) as the first line of the response. This will work for all the generators on this page, including the String Generator (which could by chance produce the string "Error" in a successful response, but which cannot produce the colon character).
PS. all of the above mentioned random number generators accepts only HTTP GET requests, so parameters are passed via encoding in the URL.