What incentives does Upwork offer to keep contractors using their platform in light of contractors operating across multiple platforms?

On the supplier side, it really depends on the labor market when it comes to multi-homing. We saw that we were able to retain our best performing supplier contractors. One big driver is the reputation they're building on the platform. The more hours they work on the platform, the more ratings they get, the more reviews they get, the more they invest in their profile by adding samples. The more we track—because we can, these platforms can track the work that's getting done—the more we can see verifiable work that's been completed and other quality signals, and all these things add up to a reputation and a brand for the supplier. That brand, for the best people on the platform, not necessarily for a new entrant, is a big reason to stay on, because it makes it so much easier to get your next job. 

In fact, the people with the best brands will get work coming to them just automatically. Because they would show up higher in search results, they have different badges that show that they are best performing. Platforms, like an Upwork, can give them marketplace tokens that allow them to apply to more jobs. Basically, the ability to get new work increases a lot when your reputation goes up. That's not very portable, that reputation is not portable. If you went to a new platform, you would have to build all that up again and go through that.

In the case of services marketplaces, there are services that are differentiated, services where there's a relationship between the buyer and the provider, and with those services, reputation matters. In the case of a fungible service, a completely transferable service, like a taxi service, really it doesn't matter who the supplier is, as long as they meet a certain threshold and you can get from A to B. But if you're hiring a programmer, or you're hiring a product designer or a marketer, then yes, their reputation matters, and how you differentiate compared to other professionals matters. That's where the reputation comes in, and that's what makes it less amenable to multi-homing, once you get established. 

Then beyond that, of course, you have productivity benefits, like the automation of the workflow post-match, the automated invoicing, the payment protection, the speed with which you get paid. All those benefits, post-match, are a secondary value proposition that provide differentiation to platforms. 

I would say the biggest is the brand - it's just like in the real world, once you build up a brand in a certain area, in a certain city, if you go to a different place, you have to build up your brand again. For differentiated services, that's pretty sticky.