Greg Brockman

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#define CTO

I joined Stripe as an engineer in 2010. I began by working on the backend infrastructure: designing the server architecture, creating our credit card vault, and producing internal abstractions to make people’s jobs easier. I loved writing code, but I also spent a bunch of time on other things: figuring out our recruiting program, shaping the culture, or making our first T-shirts (which have been banned since we hired our first designer). I wasn’t doing these things particularly because I preferred them to coding: instead, I had a very strong vision of the environment I wanted to be a part of, and I was willing to go out of my way to make it exist.

As time went on, I accumulated more and more responsibilities which were not strictly writing code. As Nelson Elhage liked to put it, my job became full-time “early employee”. My days were filled with writing cultural guides, acclimatizing...

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A Twitter bot which issues its own currency

(Update: I’ve now taken my instance of the bot down, but the code should still work if you want to run your own.)

I spent some time this weekend putting together a proof-of-concept Twitter bot which issues its own “upvote” currency. You use it by tweeting something like the following:

@stellarjob +++@thegdb cool bot! 

Live demo

http:/.test(d.location)?'http':'https';if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src=p+'://platform.twitter.com/widgets.js';fjs.parentNode.insertBefore(js,fjs);}}(document,

The bot then walks the user through linking their Stellar account and extending trust for its +++ currency. Once the trust has been granted, the bot issues a +++ credit. Each subsequent upvote results in another +++ being issued.

Because the credits are issued on Stellar, they can be seen on the account viewer, or even traded on Stellar’s distributed...

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What to build on Stellar

Many people have started building Stellar applications and infrastructure, but even more have been asking for suggestions or a place to get started. Here are a few examples of the kinds of things you could build on top of Stellar. They’re not all new ideas, but they would be new to the Stellar ecosystem.

Applications

  • Games. Many games already have virtual credits. Imagine embedding those credits into the Stellar ledger (or just making those credits be stellars). This would make them instantly tradable, and something that users could bring with them from game to game.
  • Psychology experiments (just let people know that they’re in an experiment). There are many classic experiments, such as the dollar auction, which are really interesting to read about. With Stellar, you could actually implement them and see how people behave in practice.
  • Apps for tracking and paying back expenses among...

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Setting up federated addresses with Stellar

Fun fact: the username you sign up with on Stellar’s hosted web client is actually a federated address rather than a username. That is, the username gdb is actually short for [email protected]. If you control a domain, you can set up federated addresses for your domain.

We’ve now set up federated addresses on stripe.com. You can now use your client to make a payment to [email protected]

Setting up federation

You can set up federation for your domain too — it’s pretty easy (though per the below, the protocol may end up being changed). I’ll walk you through how a client or browser resolves [email protected].

stellar.txt

First, the client finds Stripe’s stellar.txt file by requesting the following URLs until one works:

  • https://stellar.stripe.com/stellar.txt
  • https://stripe.com/stellar.txt
  • https://www.stripe.com/stellar.txt

We’ve set up our stellar.txt on stripe.com, which is served as follows:...

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The Stellar object model

Stellar attempts to encode a relatively direct model of real-world finance. Here’s an overview of the main concepts you need to know to start building using Stellar’s API.

Credits

Think of the credit system as a graph. Each account is represented as a node, and the credits are represented as per-currency weights on the edges. For example, if Joyce owes me 10 GBP, then from my perspective the balance between us is set to +10 GBP. If she later gives me 15 GBP in person, then our balance should adjust down to -5 GBP.

From her perspective, everything is the same except the signs are reverse.

Note that it’s possible to issue credits in arbitrary (even user-defined) currencies. The implications here are pretty interesting, and I’ll likely address them in a subsequent post.

Trust

Trust lines are effectively permission for an edge’s nodes to move the balance in one direction. By default,...

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