Reduce the global carbon emissions by playing a Blockchain based game? 👀 Watch the full interview here: The Story? 📝 Imagine, the Evil Lord C.O. the 2. of the Disposable Islands has declared war on our planet and all living creatures upon it. The o...

Hey! Welcome to this first edition of Block On Air, where we share technical-focused insights for you and everyone interested in the blockchain space. As this is a fast paced and ever changing ecosystem, we aim to provide you with everything from new t...

In this video you will learn about all available methods to upgrade Smart Contracts. We are gradually going from logic/storage separation over Proxy patterns to most sophisticated techniques to exchange Smart Contracts  bytecode using CREATE2. I hope th...

In this video I'll show you how you can "unstuck" your pending Transactions on Ethereum. Did you know? You can update Ethereum transactions or cancel Transactions altogether. You can do it from MetaMask conveniently with a button, or you can also unstuck...

Introduction Uniswap is a platform (or protocol) on Ethereum to swap either Tokens<->Ether (V1) or Tokens<->Tokens (V2). But how does Uniswap work as an integration to your website? Here is my step by step walk-through, from a developers perspective. A wa...

Solidity 0.6.4 [https://github.com/ethereum/solidity/releases/tag/v0.6.4] deprecated something which almost slipped my attention. address.call.value()() was deprecated and got replaced with address.call{value: x}(). Let's check out how this works. Whe...

In mid 2019 I started to look for Enterprise-grade hosting solutions. Why? Because we already work with Docker and Git in our teams. So, the next step was to see if we can transform our self-hosted cluster solution on bare metal and with something more ma...

So, you heard the news: Solidity 0.6.0 is out. And it got some breaking changes [https://solidity.readthedocs.io/en/v0.6.0/060-breaking-changes.html#explicitness-requirements] ! In this post & attached video I want to go through some of the changes hands-...

Today a post from my life instead of Blockchains. I bought a new Laptop. I was thinking about it for quite a while and the timing seemed just right, as my old one [https://geizhals.at/asus-zenbook-ux310ua-fc339t-quartz-grey-90nb0cj1-m05300-a1542483.html] ...

Do you really know Ethereum well? Today I got 5 questions every Ethereum Blockchain Developer should know. Some are super easy, some are quite hard, none of them should feel unfamiliar. Watch the video, you might learn something new today!!! Ethereum B...

In this post I am comparing three things: 1. local (web) development, 2. classical virtualization using Hypervisors such as Virtual Box, 3. containerization and orchestration tools such as LXC, Docker, docker-compose, docker-swarm and Kubernetes. On top, ...

So you built your decentralized Application. But then? Of course, you need to monitor it. Because always manage the money at risk and that includes proper monitoring. There are a few resources out there to monitor decentralized applications. This blog po...

Today I want to talk about 4 things you didn't know about Blockchains, Hyperledger, Ethereum and general Smart Contract Development. In this video I will show you how to setup Hyperledger Besu on your development machine, how to supercharge your dev-envir...

Is developer demand raising or falling? What's the cost of Blockchain education? What's the average salary for a Blockchain developer? How long will it take to become a successful Blockchain Developer? ... and many more! Let's get into it.

Beginning of 2019 I got frustrated. I used Vagrant and the ScotchBox for Web-Development. But it was hard to switch to new PHP or MySQL versions. It was hard to get the whole team onboard. It was hard to have the exact same configuration everywhere. It wa...

We already covered the difference between .send() and .transfer() in another blog post [https://vomtom.at/solidity-send-vs-transfer/]. But now, someone in our Udemy courses asked the great question: "How can a .send() transaction fail"? Send transfers an...

In this post I'm going to tell you what exactly an account on the Ethereum Blockchain is. We are also talking about how an address is really created internally. And what the private key is for anyways. So, when you are sending Ether, you are usually send...

What's an ABI Array? What's the Account Nonce? What's the difference between Ether and Ethereum? This and many more questions explained!

This is a question someone asked recently. And right so! To the seasoned eye it looks like a mix of different technologies just randomly mixed together. For beginners it's extremely hard to keep these things separate at first. Let me quickly answer it: ...

Someone in our Facebook Group asked how to return a Mapping in Solidity. It's not possible. But can you eventually return a struct with a mapping? Would that work? I will give you a spoiler, the short answer is: you can't and it makes no sense. But there...

Blockchain Technology and the Education System Education is one of the key areas of focus in most developed countries as advancement in other sector hinges on the level of education. Regardless of the marked improvement in technology, there is still a nee...

So, Facebooks Crypto-Ads are back [https://www.facebook.com/business/news/updating-our-ad-policies-for-financial-services-and-products] . You've probably heard it. And Bitcoin made a jump as well, which hopefull didn't surprise anyone. I've long said tha...

It took 11 posts until he wanted to delete something. [https://www.reddit.com/r/ethereum/comments/bki0u9/my_first_case_of_wanting_to_censor_someone_using/] . New Record! Lucky for him, it was so early. His new dApp was just released on the Rinkeby-Testne...

Isn't that amazing? You can take your crypto and spend it on real-world items. You can go on a shopping spree on Amazon. I did. I tried and failed. It's actually pretty straight forward if you think about it. You purchase an item on Amazon. And, instead ...

Have you seen what happened between Elon Musk and Vitalik Buterin on Twitter yesterday? Elon, the founder and CEO of Tesla - probably everyone knows him by now - had Vitalik Buterin, the co-founder of Ethereum, report to him DIRECTLY VIA TWITTER. First ...

A few days ago I asked how blockchain technology can help reduce the cost for insurance settlment and other overhead costs [https://www.youtube.com/watch?v=X2jXgdA8rQE]. How much are the settlement costs? The answer, how blockchain disrupts the Insurance ...

Ethereum is often coined unsuitable for banks and financial insitutions because of the lack of privacy. "Banks will never go public with their data, it's simply not possible, regulatory issues, can't do" - you might have heard or even said something like ...

In this Ethereum Session we talk about Immutability, or why it isn't really possible to delete information from the blockchain at all. Even though you delete your smart contract via the "selfdestruct" command, it's still not possible to completely remove ...

Have you ever wondered how a Public Notary system would look like on a public permissionless Blockchain like Ethereum? Then you will most likely enjoy this video: Find the demo here: https://tomw1808.github.io/ethereum-blockchain-entwickler-kurs-2018/ ...

Have you ever asked yourself why should we use Blockchain instead of traditional systems for IoT? If yes, then, that's good. That is valid question and I will explain to you the answers using a Car Sharing example. In the video below, we'll go through th...

Have you ever wondered where the imported wine you are drinking, the shirt you are putting on, or the food you are about to buy come from? Aside from the shopping malls you go to, there is a whole other links of different elements that come together into ...

Oracles! What are they? And why do we need them in Ethereum? One of the major benefits that we have on Ethereum is that the Smart Contracts are running on a Sand Box and they can’t do http codes, and can’t access hardware layers. It’s basically a bunch o...

Solidity v0.5.0 is out for about 2 weeks and now we can use it in Remix. To read more about the changes made for this version and how you’re going to update the affected codes, refer to this documentation [https://solidity.readthedocs.io/en/latest/050-bre...

In this video, we are going to discuss the new MetaMask Privacy Mode. This came into effect on November 5, 2018, and will be set as mandatory pretty soon. With this in mind, I will show you the effects of using the old and new method through a side-by-si...

Let's give the Enterprise Ethereum: Pantheon a try - a freshly coded, written in Ethereum Node straight from scratch. So, in this video, I am going to walk you through the steps on how to install Pantheon by following the installation guide from Pantheon...

It's done. Over 300 pages. Full of knowledge. The Ethereum Blockchain Developer Book. It starts very gentle, with Remix, teaching some Solidity basics. But quickly guides you through the whole workflow of a typical Blockchain Project. In die book you wi...

One part of being a trainer is to answer questions. Sometimes complex questions, sometimes simple ones, but there is never a stupid question. A typical example for such a question is this one: How to interact with an Ethereum Smart Contract once it's deployed using JavaScript?

Solidity Anfänger oder Ethereum Interessierter? In diesem Kurs lernst du nicht nur die Grundlagen, sondern auch den sicheren Umgang mit Solidity und die aktuellen Industry Best Practices! In einfach zu verstehenden Lektionen lernst du Schritt für Schrit...

With this course we guide you through the CBDE - Certified Blockchain Developer for Ethereum. This certification, which was created in partnership with the Blockchain Training Alliance and Pearson VUE, is helping HR and global corporations to find the ri...

In this episode we are looking at the Ethereum Messenger “Status”. It’s a mobile app for Android and iOS that should bring the power of the Ethereum Blockchain to your phone. We’re going to look what it can and cannot do with hands-on and in-depth program...

In this video we are talking about Gas! Specifically, we are deep-diving into the Gas Limit and the Gas Price and what it’s all about that. So, there the two things. The Limit and the Price. But where does it come from and what does it mean? Let’s put ou...

It's not easy to get Upgradeable Smart Contracts right. You should be able to fix bugs or enhance features, obviously. But not at the cost of loosing immutability. It's this element of trust that nobody - not even a trusted entity - can change anything. T...

Recently I was in Manila and I thought: "What if I forgot my Credit Card and still have some Ether left?". Can I still get money without the help of my Embassy? This video shows where we are end of 2017 with Bitcoin ATMs. Did I get my Cash at the end? An...

While for many people it's the most obvious thing, for others it's not. Investing in an ICO. Properly and Safely! You might know that situation. You see an investment opportunity somwhere and you just need to send some Ether to an Address - and voilà - y...

Truffle 4 [https://github.com/trufflesuite/truffle/releases/tag/v4.0.0]: Just released and packed with exciting features, we are looking close into Debugging and Testing. In this Ethereum Session we are going to deep dive into Truffle 4 new features. I'm...

With plenty of tools out there, and many more in the making, the Ethereum Ecosystem is evolving so fast that it's hard to keep up. I work with plenty of tools on a daily basis and I see that it's just confusing for new developers to understand what-is-wh...

Investing in ICOs is easy. Just send money to a contract and receive tokens in return. Successful investing is a different story. Most tokens out there are completely useless. I will tell you exactly how to spot them before you loose money!

In this short video we look at the difference between .call() vs. .delegatecall() vs. Libraries in Solidity. Specifically we look at a very simple contract that emits an event with the address of the global variable this. This has caused some confusion...

With the massive success of Ethereum ICO is being used all the more for funding the development of similar crypto projects. In case you’re willing to know better about Ethereum ICO and their legal tidbits, here is a detailed insight on leading ICOs in the market

A Comprehensive Course To Help You Understand, Evaluate & Invest in Cryptocurrency ICOs, Without Being Caught By Scams! Initial Coin Offering A-Z™: Become A Smart ICO Investor - is the most complete course helping you to understand, evaluate, and make sm...

In this video we are having a look at Mappings and Structs in Solidity. This is one of 110 video-lectures in the Ethereum Developer Masterclass [https://www.udemy.com/ethereum-masterclass/?couponCode=VOMTOMWEBSITE10] where you will learn everything there...

100% FREE COURSE: Build A Hello World Blockchain App - is the only course you need to begin your journey with Ethereum Blockchain Development incorporating Solidity at a basic level, with step-by-step instructions guiding you through the entire process.

The new Solidity 0.4.16 is out. In this verison the new "view" and "pure" functions are introduced. I had a quick look what this means for you as a Solidity Developer in this Video. Interested in a more thorough course? Join the Masterclass for $10 only ...

Ethereum Developer Masterclass: Build Real World Projects - is the most complete Ethereum Blockchain Development course online helping you to build complex, real world, ethereum based distributed applications successfully.

Since version 0.4.13 we have a new Exception handling in Solidity. Instead of a simple throwwe have now revert(), require() and assert(). In this short video I'll walk you through the exact difference between the old and the new exception handling. We h...

Have you ever wondered why it is not recommended to keep the coins in an Exchange? There are many reasons for that, but most importantly, they are not yours. You are not in control. In this video I'll walk you through the underlying theory why you should...

Der Handel mit Kryptowährungen wie Bitcoin oder Ethereum wird immer beliebter. Große Volatilität, starke Renditen und ein Bisschen das "Ungewisse wie im Wilden Westen" lassen derzeit Handelsplattformen von Kryptowährungen nur so boomen. Inzwischen gibt es...

A short notice on the two functions address.send(amount); vs. address.transfer(amount); Since version 0.4.13 (actually since this [https://github.com/ethereum/solidity/issues/610] issue is resolved) Solidity has one new important function, the trans...

This is a letter to my younger self, discovering Hong Kong for the first time with tips and tricks I wish I knew... > I am from Austria and my wife is from Hong Kong. Since we spend quite some time in Hong Kong, I ran into a lot of things that are comple...

Every once in a while I dump the links that land in my bookmarks. I find these links mostly through HN or Reddit, or somewhere else on the web. My focus is mostly on "fun things", from web-development tools, machine learning to ethereum. Those are the ar...

This is one of the largest, most in-depth ethereum development courses online. The curriculum contains a number of practical exercises, which will help you put all the knowledge you’ve learned into practice to create something of value.

A Platform that makes it possible to find stolen bikes again Created 2008 it was among the first platforms I was writing. The idea was pretty simple. Add your bike while you have it. Once its stolen, just activate it and it will be shown on the map with ...

Sometimes want to quickly share a Password with your friend? RSA Message Sharing Tool is right for you! I works entirely in the browser, doesn't save any information anywhere and uses throw-away keys. Technologies & Idea We use 1password a lot in our off...

Platform for Holiday Apartments and Places to go Technologies Pimcore [http://pimcore.org], OpenWeather API, Elasticss, JQuery and Jquery Addons (Lightboxes,...) Idea In southern-western Peloponnese the tourism isn't as well developed as on the Greek "Pa...

Interesting Bookmarks I gathered in the past few weeks. In this post I'll present the bookmarks I made in the past few weeks. I love interesting bits and pieces and from time to time I dump them into a blog-post. Most things are either free or directed to...

Problem: On a Windows host, Vagrant won't have symbolic links in the shared folder If you are like me, you love Vagrant [https://www.vagrantup.com/]. One of the problems in recent months was that on my linux-guest system the symbolic links won't work. Lon...

WordPress Alternative for Freelancers/Agencies/Teams: Including Git, Vagrant, MySQL, Bootstrap-Theme Implementation Click here to Enroll [https://www.udemy.com/enterprise-cms-applied-implement-a-website-with-pimcore/?couponCode=VOMTOM15] * Want to know h...

Become a Shopify Master! Start successful selling with Shopify today and learn how to use Google Analytics, Mailchimp and Facebook Ads on top! *** No complicated setup * No installation * No programming required * Start selling TODAY with Shopify! *** Ci...

Hashtag #BCSC16 on Facebook and Twitter I am updating this article throughout the day as events occur. Pass by every now and then. Today I am happily attending the Blockchain Startup Contest 2016 [http://blockchainstartupcontest.com/]. The BCSC 2016 is t...

A Shop for alternative health products My mother sells olive oil. It's not the usual olive oil. Yes, it's extra virgin, organic, Greek olive oil. But she takes extra care: for example, not even the fields around her olive fields are allowed to use pestici...

Complete Tutorial for Solidity and Web3 on static Github Pages Before the creation of the Ethereum Course on Udemy I created a small Tutorial on how to create Dapps [http://www.newscombinator.com/article/8/hacker-news-style-list-on-the-blockchain] by cre...

News aggregator and news classification in real-time. Started 2014 and ongoing, one of the biggest topics in the past years for me: working with textual data. News, Blogs, Articles, Comments, name it. My work for my master's thesis included a classificati...

A Quiz-App for Android. Supports self-made quiz-catalogs, downloads and highscores. Language: PHP/HTML/JS/Java. Year 2010/2011. Platforms: Android with a RESTful PHP-Backend. Started as a University Project, it became a fully featured Android-App for Qui...

Ethereum Developer: Build A Decentralised Blockchain App, is the most comprehensive course on building a decentralised blockchain application anywhere on the web.

Open Source Location Service and News I had the idea on a flight from the Philippines to Hong Kong in 2015 reading a Newspaper. RefugeeBuddy - On Android [https://play.google.com/store/apps/details?id=com.vomtom.refugeebuddy] The RefugeeBuddy helps peop...

Created 2007/2008. One of the biggest projects, which I crafted alone, was a platform for renting out real estates. The first version was quickly made in a few weeks, called mietenkaufen.at. Superseeded by a second version, multi lingual, multi category,...

Hi, I'm Thomas. I am a CTO. I am a senior back-end developer. I am a systems architect. With 20+ years hands-on development experience. In all kinds of languages and systems. I have a CS masters degree. I am working since 2016 with Ethereum and Blockchain...