Say Hi to Guesser — Peer to Peer Betting Built on Ethereum

A Ðapp where anyone can create betting events

Betting games are old. Really, really old. Yet, for centuries, people have only been able to bet on what a few companies or governments decided. Mostly, that has been some kinds of sports and more rarely politics.

If you think about it, you can bet on pretty much anything. Will a certain Youtube video exceed a million views? Will SpaceX’s launch be successful or will the rocket crash? Who will win E3’s Fortnite battle royale? The internet has proved people’s creativity can be endless, but in order to have fun betting we still rely on a bunch of companies to create these betting events for us.

Until now.

🔮 Introducing Guesser

Smart contracts allow Guesser (guesser.io) to connect bet creators with players in a trustless way. You don’t have to trust Guesser to create the events or ensure any payment: peer to peer transactions are made possible by Ethereum’s smart contracts.

  • Anyone can create a betting event. Not only that, but anyone is incentivized to create them, as the creator will earn a fee of all the money players stake at the new event. You only have to provide a title, description, topic, possible outcomes, and set a final date!
Creating a betting event on Guesser’s testnet dapp
  • Anyone can bet. Ethereum is all about unstoppable applications, and the Guesser dapp lets anyone have fun and participate in a bet of which you believe you can predict the outcome. You choose an event and place your bet (in ether) on the desired outcome.
Betting on Guesser’s testnet dapp

Who settles the bets? In our Rinkeby release, outcome validation is done by community votes (it’s a quick fix that would clearly face trolling once we go live). Long term, we plan on relying on an oracle. Working at Witnet, a decentralized oracle network, I’m learning a lot about oracles’ nature and why they solve a great problem. Since decentralized oracles are not available yet, we are working on a design involving creator settlement and community reviewing for the near future. More to come on that matter soon!

How are rewards distributed? On our first version, bets were binary (two possible outcomes).When a betting event ends, people who bet on the winning outcome get back their money plus the money staked by others on the losing outcome (given out proportionally to how much money you staked in the first place), minus the creator fee (currently 1% of all money bet on the event). We are now developing new, different betting contracts that will allow creators to play with different types of outcomes as well.

🔗 Progress

We launched Guesser on Ethereum’s Rinkeby Testnet a couple of months ago. Without making too much noise, we tested features, found bugs, fixed them, found more, fixed them too… You know how it goes.

We’ve learned a lot from our testers in the process, and the dapp is currently undergoing a rewriting of many parts of the code and the smart contracts. In the Dapp space, User Experience can still be done much better, and we’re also happy to face these challenges and deliver a great product to our users.

We want Guesser to be a community-run platform. The community creates bets, the community bets, and we also want the community to help us buidl. That’s why in addition to being open source we’ve recently started to work on the Guesser Protocol, a set of smart contracts that will let developers build all sorts of decentralized betting products on top of Ethereum.

🛫 What now?

We are currently working on the refactoring of the code towards the much improved next release of Guesser. The most important steps in our gearing up are:

  • Rewriting the smart contracts and auditing them
  • Improving the platform’s UX based on community feedback
  • Specifying bet settlement procedure
  • Keep growing and engaging community around the platform
  • Cool new stuff like opening bets to ERC-721 tokens — that’s right, get ready to bet your kitties! 😼
One of Carlos’ sketches of Guesser’s architecture

We are skeptic of deadlines, but we should be able to finish implementing most of these in a couple of months. Meanwhile, we keep working really hard behind the scenes to ship a great product anyone can use.


Most of us who have been working in crypto for some time feel part of a greater mission. We at Guesser believe that fun products anyone can play with will be key for this technology to gain adoption, and that goal is one of our greatest drivers.

While we build, you can still try our first testnet release by creating fun betting events and bringing on some friends to take a bet at the outcome. We’d love to get further feedback from the community.

If you’d like to reach out, be sure to follow us on Twitter or join our Telegram chat!