My advice is to take it one step at a time to protect your interests. If the buyer wants your extension, then there are not abundant alternatives in the market.

First, ask the buyer what they have used in the past. This will provide information into their legitimacy and provide a starting point for your research.

Next, ask for a term sheet. Again, this is both a measure of legitimacy and a starting point.

Finally, ask for references regarding similar transactions.

If the other party doesn't present themselves as experienced in this sort of thing, consider it a yellow flag. Don't kid yourself that what looks like a red flag isn't a red flag. International transactions are complex and getting your money won't be easy if someone doesn't want to pay.

If things are proper, the deal could easily close in thirty days or so. That's not to suggest that you need to drag things out, only that it might be wise to take the time to perform some due diligence regarding the counter-party. Particularly since your experience is limited.

Good luck.

This could greatly tarnish the reputation of the OP and therefore should ask the company what they plan to do with the extension. If the answers are vague and it does not look like the company is buying the extension for the benefit of the consumers, walking away from the deal might be a better situation.

[1] - http://www.labnol.org/internet/sold-chrome-extension/28377/ [2] - https://www.reddit.com/r/IAmA/comments/1vjj51/i_am_one_of_th...

http://www.investopedia.com/ask/answers/06/202005.asp

Escrow.com (a service recommended in many of the comments below) has an article mentioning them:

https://www.escrow.com/news/Articles/the_advantages_of_using...

Personally, I have used Wire Transfers as the goto option. I have never used escrow.com but the fees seem reasonable for a smaller deal. But honestly if the deal is anywhere around $20k or more then I'd get an attorney to handle the transaction part and have the attorney make sure to protect you from liability down the road.

And especially since it is international I'd specify US Dollars and Wire Transfer. I know the US Dollar specification sounds crazy but you'd be amazed what games people will play.

Definitely an infinitely better solution than escrow.com, and assuming I've guessed the extension right you'd probably have to pay almost a thousand dollars of fees on there.

International wire transfers are irreversible, so that's just as good as having them give you a briefcase full of cash. Actually, even better since you can't really receive a forged wire transfer.

(Edit: Not sure why I'm getting downvotes, am I wrong?)

There's not really anything he needs to do after he receives the money, the contracts should be signed before the money is sent and only become active after the money is received.