Hicdex is a Tezos indexer focused on Hic Et Nunc (HEN) NFTs and smart contracts activity.

Indexers play an essential role in providing quick and scalable access to the data persisted in blockchains. Indexers are the backbone of many apps and services in all blockchain ecosystems.

The hicdex developer, @marchingsquare, created it as an easy-to-use API for third-party developers to create websites with HEN data. However, it has become a critical backend for the HEN marketplace. Many third-party tools and sites use hicdex, including Cyber metaverse, NftBiker’s tools, and hen.radio.

The traffic to HEN is growing exponentially, placing a lot…

In part 2 of this series, I discussed how Hic Et Nunc (HEN) smart contracts are used for swapping and collecting NFTs.

In this third and last part of this series, I will go over the rest of the smart contract features that make HEN work.


The GUI for canceling is implemented in hicetnunc/src/pages/objkt-display/tabs/collectors.js using the React JavaScript library.

The GUI code requests funds from a Tezos wallet and swaps the artwork in src/context/HicetnuncContext.js in the cancel method.

There are two main steps for canceling:

  • Request funds from a Tezos wallet to cover the blockchain fees. …

In part 1 of this series, I discussed how Hic Et Nunc (HEN) smart contracts are used for minting NFTs.

Due to an exploit, HEN had to deploy V2 versions of the smart contracts. Now, most of the HEN features are implemented using the V2 smart contracts.

I will also discuss the V1 smart contracts exploit that drove the changes for the V2 design.


The GUI for swapping is implemented in hicetnunc/src/pages/objkt-display/tabs/swap.js using the React JavaScript library.

The GUI code to request funds from a Tezos wallet and swap the artwork is in src/context/HicetnuncContext.js in the swapv2 method.

There are…

Hic Et Nunc (HEN) is an experimental non-fungible token (NFT) marketplace covering a wide range of visual art, interactive art, music, and animations from a diverse group of artists worldwide.

To create an NFT on HEN, an artist needs to go through a minting process which creates a record of the art information in the Tezos blockchain.

HEN utilizes smart contracts to manage the minting, selling, and buying processes to ensure the artist is paid for each sale and receives royalties for secondary sales.

Hackers recently stole digital artworks from HEN due to an exploit in one of the smart…

At the end of 2020, I started learning 3D design using the open-source Blender creation suite. The last time I tried a 3D graphics tool was eight years ago when I used 3D Studio Max during a short-lived interest in 3D printing.

I don’t find 3D modeling that engaging, but using Blender procedurally to create abstract artwork caught my attention. In particular, the fantastic work of a Blender artist, Midge Sinnaeve, inspired me to spend the next several months learning the tool to create art.

I’ve created a persona for my art called NoRulesJustFeels. I’m still very much in the…

Video can be a very effective way to use high-production visuals in your Interactive Canvas game for the Google Assistant. In a previous post, we discussed using video loops in an Interactive Canvas web app.

This post discusses the necessary steps to prepare video files and to write the JavaScript logic to play seamless video loops in an Interactive Canvas web app.

Seamless video loop for Interactive Canvas

Media Source Extensions

Creating seamless video loops requires using Media Source Extensions (MSE), which is a browser feature that extends the HTML media element to allow JavaScript to generate media streams for playback.

You have to write JavaScript code to download…

Using Interactive Canvas to create an Action for the Google Assistant combines the best of conversational interfaces with the rich visual capabilities of HTML.

We’ve been using Interactive Canvas for a while, experimenting with various ideas and working with partners to launch their Actions. Along the way, we’ve learned some lessons about what works well, and we’ll pass these on in this post to help you create a successful Action using Interactive Canvas.

Note: At this time, Google is only approving Canvas Actions that are gaming experiences.


Actions using Interactive Canvas are conversational Actions. You should start designing your game…

At I/O this year, we announced Interactive Canvas, a new way to build immersive, full-screen experiences that combine the power of voice, visuals, and touch on Smart Displays and Android phones. Starting today, you can build and deploy your Interactive Canvas Action to users. Interactive Canvas is currently only available for games, but we will consider other verticals in the future.

With Interactive Canvas, you can create Conversational Actions that have rich, full-screen visuals and media using existing web technologies: HTML, JavaScript, CSS, and WebAssembly. …

In a previous post, I discussed the design and implementation of my Magnificent Escape game for the Google Assistant. I’ve received lots of questions regarding the code and the Dialogflow agent. So, I’ve decided to open source the game.

I’ll explain how the project is organized and also discuss the latest learnings from the game in this post.

Github repo

The game’s Dialogflow agent and fulfillment source code is available on GitHub. Some of the main files include:

  • app.js — the main entry point for the Node.js app, which launches a web server for handling the Dialogflow agent fulfillment.
  • fulfillment.js — the…

Did you know that you can let your users record their own audio for a Google Assistant Action? In this article, we’ll show you how to create a simple prototype that allows users to make an audio recording that can then be played back on the Google Assistant.

We need a way for users to record audio. However, we didn’t want to make the user install another app, so we decided on using a web page instead.

Actions on Google supports playback of audio with either SSML, which is limited to 240 seconds, or with a media player for longer…

Leon Nicholls

Former Google Assistant Developer Relations Engineer

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