This validator is a free service. Please help keep it free by using it appropriately.
You may use this service interactively to validate your own, or anyone else's, syndicated feed.
You may use this service interactively to validate test feeds in the course of building software that produces syndicated feeds. In fact, you are encouraged to do this. Validate as often as it takes to get your feeds right. Please.
You may provide a direct link on your own site to the results of validating your own feed. The results page will give you this link, once your feed validates. You are encouraged to provide this link to show that you care enough about standards to produce a valid feed, and to encourage others to do the same.
You may not build a frontend on this service that takes the results and passes them off as your own.
You may not "frame" this service by putting it in a frame of your own site.
You may not use this service to implement denial of service attacks on other sites.
You may not send automated queries to this service. For example, you might want to build a program that includes feed validation, so you might try to write a script that queries the online validator and scrapes the resulting HTML. This is not allowed. The validator itself is open source; please download it and use it locally.