In 1997, Hastings worked on cryptographic protocols and tools free of U.S. cryptographic export restrictions with Vincent Cate, who started the International Conference on Financial Cryptography in Anguilla that same year.
Hastings founded HavenCo in 2000, originally incorporating in his country of residence, Anguilla, before a second incorporation in the Channel Islands. Hastings was the CEO; other co-founders included Ryan Lackey and Sameer Parekh. Immediately following its public launch, HavenCo was the subject of a great deal of press coverage, including Hastings' appearance, along with several cofounders and the "royal family" of Sealand, on the cover of Wired's July 2000 issue, before the company was entirely nationalised by the government of Sealand in 2002, after commercial failure and mounting tensions.
In 2002, Hastings began work on seasteading with Patri Friedman, a project aimed at building floating communities free from the restrictions of current governments. This collaboration continued through 2009, including a talk by Hastings at the Seasteading Institute's annual conference.
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- Fischermann, Thomas (April 12, 2003). "Die Piraten des 21. Jahrhunderts". Die Zeit. Retrieved May 2, 2009.
- "Privat war gestern". Die Zeit. August 5, 2008. Retrieved May 2, 2009.
- Garfinkel, Simson (July 2000). "Welcome to Sealand. Now Bugger Off". Wired. Retrieved May 2, 2009.
- Platt, Charles (July 1997). "Plotting Away in Margaritaville". Wired. Retrieved May 2, 2009.
- Ward, Mark (June 5, 2000). "Offshore and offline?". BBC News. Retrieved May 2, 2009.
- "Stranger Than Paradise". On the Media. NPR. May 20, 2005. Retrieved May 2, 2009.
- "The Ultimate Offshore Startup". Wired. July 2000. Retrieved May 2, 2009.
- James Grimmelmann (March 27, 2012). "Death of a data haven: cypherpunks, WikiLeaks, and the world's smallest nation". Ars Technica. Retrieved April 16, 2012.
- Ryan, John; George Dunford; Simon Sellars (2006). Micronations. Lonely Planet. p. 13. ISBN 978-1-74104-730-1.
- Sean Hastings - Experiences with HavenCo and SeaLand Seasteading Institute, February 12, 2009