Gruber later mentioned on Twitter [1] that in some months they're paying more for servers than they're spending on the font in an entire year. (The font licensing is $299/yr [2], suggesting server costs around $3600/yr.)

[1] https://twitter.com/gruber/status/768302562030202881

[2] http://www.typography.com/apps/

Curious. You should be able to run an (evidently not that popular) text sync service on a Hetzner box for a fraction of that price. I wonder what was costing them $3600.

I'm not certain if it's still the case, but Vesper Sync was originally written using Azure Mobile Services.

https://channel9.msdn.com/Blogs/Windows-Azure/Learn-how-Vesp...

During many Azure ad spots on The Talk Show, it had also been mentioned that Vesper used it.

Substituting the paid font(s) with freely available alternatives shouldn't be a big deal, no? Less pretty, but still usable.

I would imagine so, but he didn't mention that option in the article.