Hello, Wajid! Work authorization would be something specific to the employer offering a position. We do primarily work with US-based companies featuring US-based jobs. We do have some international positions, which can be found at this link http://www.flexjobs.com/us/Anywhere-telecommuting-jobs.
We do have hundreds of international jobs that can be viewed at the above link; spanning all 50+ job categories we offer, and the opportunities change daily and go from executive to entry-level opportunities.

For more information on finding flexible international jobs on FlexJobs, please read the following blog: http://www.flexjobs.com/blog/post/faq-finding-international-flexible-jobs-on-flexjobs/

Please feel free to reach out if you have any further questions!