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Questions tagged [dapps]

Questions about applications and projects on Ethereum: a decentralized application (dapp) does not require any servers or backends and runs independent on a distributed blockchain.

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133 votes
6 answers
147k views

What is a DApp?

There are new terms in Ethereum like smart contract. What is a DApp and how is it different from smart contracts?
eth's user avatar
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56 votes
2 answers
26k views

What does the keyword "memory" do exactly?

I've been looking through the code of Etherdice and noticed that some variables are declared like ParserResult memory result; and I haven't found the keyword "memory" in any documentation. ...
uberlaufer's user avatar
53 votes
3 answers
24k views

What is Whisper and what is it used for?

It's admittedly a very general question, but I've heard "Whisper" mentioned in several places when reading about certain DApps. I understand it allows peer-to-peer messaging of some kind, but what ...
Richard Horrocks's user avatar
47 votes
1 answer
7k views

How do I make my DAPP "Serenity-Proof?"

When Serenity comes around, the network will undergo many changes, some of which may have unexpected consequences on existing Smart Contracts. How can I plan so that I am best prepared to take ...
Tjaden Hess's user avatar
  • 37.1k
35 votes
7 answers
50k views

web3.eth.contract is not a function when making contract

Whenever I try and make a contract, I get: web3.eth.contract is not a function I'm using this code: const path = require('path'); const fs = require('fs'); const solc = require('solc'); ...
ErwanLent's user avatar
  • 541
35 votes
2 answers
20k views

How does Lisk differ from Ethereum?

Lisk is going to be a full stack DApp development framework for building and distributing decentralized applications. It's currently in the crowdfunding stage but got also added to Microsofts ...
q9f's user avatar
  • 32.9k
32 votes
4 answers
14k views

How to create a Dapp from scratch on Ethereum?

Let's say we have someone who knows about blockchain but who doesn't have any background in blockchain-based application. That person wants to code an ethereum-based Dapp (decentralized application) ...
SajZ's user avatar
  • 431
29 votes
5 answers
38k views

How do I send an arbitary message to an Ethereum address?

How can I send a message to another Ethereum address? And how would that user receiving know that its a message? Is there an Ethereum wallet that will show that I sent a message to that address? And ...
Patoshi パトシ's user avatar
28 votes
1 answer
26k views

Create a two-dimensional array in Solidity

How to create arrays addresses using solidity? And we can write two-dimensional array? bool[2][] m_pairsOfFlags; Here is an example of the array, but it does not work
M.Sheremain's user avatar
28 votes
3 answers
11k views

Are there any public/free nodes to connect a Dapp front end?

I have a small Dapp written in Meteor (client only) that reads some contract and account info from the blockchain. I can deploy my front-end code for free on meteor.com (or a variety of other places),...
eterps's user avatar
  • 724
27 votes
2 answers
16k views

How can we integrate IPFS with ethereum in DApps?

How can integration of IPFS with ethereum be done in DApps? Which parts of a DApp will be on IPFS? Do any examples exist? If a DApp's site is hosted on github, is it not centralized?
siddesh sangodkar's user avatar
20 votes
3 answers
8k views

How can DApp developers profit from their work?

Suppose that I make a new, cool DApp that gets very popular. In order to cover development costs and make some profit, I charge users of the app a small quantity which is required to use to app - all ...
MaiaVictor's user avatar
  • 3,177
18 votes
4 answers
27k views

web3.js import contract abi from .json file

So I have a deployed contract with address0. I can easily interact with it using my index.html like so: import contract_artifacts from '../../build/contracts/contract.json' var contract0 = contract(...
porfavorite's user avatar
18 votes
1 answer
24k views

How to read public variable from contract using ethers.js

I am trying to read public variable from contract on chain using ethers.js. Calling the methods work but I could not manage to read public property (without getter). The methods works like this: const ...
senty's user avatar
  • 297
18 votes
5 answers
3k views

How will regular users be able to use dApps without buying ether?

Requiring users to get ether before they can use a dApp, is too much of a barrier for any kind of mainstream adoption. If dApps offer free ether in a naive way, they can be attacked by Sybils where a ...
eth's user avatar
  • 85.9k
17 votes
3 answers
3k views

What are effective and secure ways of shuffling a deck of cards in a contract?

We want to write a card game in Ethereum. What are effective and secure ways of shuffling a deck of cards in a contract, and dealing them to players? It needs to be done in a way so that no one can ...
eth's user avatar
  • 85.9k
17 votes
4 answers
10k views

What are the best practices to allow user signup and login for a dapp?

From what I have researched, it seems that all of the methods for allowing a user to signup and login for an Ethereum dapp are very cumbersome for the user to use. What are the best practices to allow ...
Jason Cochran's user avatar
16 votes
1 answer
2k views

How should I handle blockchain forks in my DApp?

In the user interface of my DApp, how can I detect that a blockchain reorganization happened and what should I do to update the UI state once the fork is resolved?
J-B's user avatar
  • 8,961
16 votes
6 answers
16k views

How can dapps work on smartphones?

How can dapps on mobile web browsers interact with web3.js? Is there any tool like Metamask or Mist on the roadmap for mobile?
Diego Cerdan Puyol's user avatar
15 votes
2 answers
19k views

Error: VM Exception while processing transaction: out of gas

I am running into out of gas exception while calling this function : contractInstance.createProposal("ADHD", "Foo", 2, {from: web3.eth.accounts[1]}) . I'm super new to ethereum and I would really ...
itachi's user avatar
  • 153
14 votes
3 answers
5k views

Do users of ERC20 coins need to hold Ether?

Suppose there exists Fancycoin, an ERC20 altcoin which has some functionality implemented by the EVM. It does some nontrivial things that take up gas. According to my understanding, I can receive ...
Wapiti's user avatar
  • 419
13 votes
5 answers
19k views

How to verify MetaMask account holder is the real owner of the address?

I'm making a dapp that will make calls to a Node.js server. I expect the user to have MetaMask installed and I want to verify that he is the real owner of the current address on MetaMask (i.e. ...
adrianmcli's user avatar
13 votes
6 answers
17k views

Is there a list of DAPPS that are already useable? [closed]

Is there a list of DAPPs that are already useable? Useable means there is an easy accessible GUI, that can interact with the contract.
13 votes
4 answers
7k views

What are the different GUI's available for Ethereum? [closed]

Are there any easy to use GUI's for Ethereum?
Dawny33's user avatar
  • 1,997
13 votes
2 answers
11k views

How do I send multiple transactions as one transaction?

Say I need a user to approve a contract with an erc20 token balance and then the contract can execute it's function after. Typically, I would have to do an approve transaction with a nonce of 1 and ...
Dylan Kerler's user avatar
11 votes
2 answers
4k views

Can I run a website 'on' ethereum or only 'with' ethereum?

Do you run a website 'on' ethereum or 'with' ethereum and if the latter, is that only with 'nodejs'?
Cisko Rijken's user avatar
11 votes
2 answers
4k views

Collecting ERC20 balances from multiple addresses?

I'm building a dApp that involves creating unique accounts for individual users for ERC20 deposits [I keep the addresses and private keys in a centralized database], for popular ERC20 tokens like BNB, ...
king_geedorah's user avatar
11 votes
1 answer
6k views

Unlock account permanently

I have created a dapp where the user can sign a contract using metamask. However, the account that gets the money send to keeps getting locked. Sure, I can manually unlock it, but this is really ...
Arko Elsenaar's user avatar
10 votes
3 answers
2k views

How would stablecoins work on Ethereum?

The idea of a stablecoin in Ethereum is to create a token that is pegged to the price of say $1 USD. What are the main ways of achieving a stable cryptocurrency? What DApps are implementing them and ...
eth's user avatar
  • 85.9k
10 votes
1 answer
4k views

How should I secure a private key in my dapp?

We are currently building an app that interacts with the blockchain. It needs to be able to make transactions on the blockchain on it's own - for instance to add addresses to a whitelist. This means ...
karianneberg's user avatar
10 votes
2 answers
15k views

How to build a front end for dApp

I am studying about DApps and Ethereum. I did get the Solidity part but I am confused about the front-end apps. Is it possible that I use web framework like PHP Laravel/Rails for Frontend/Db ...
Volatil3's user avatar
  • 337
10 votes
3 answers
1k views

Is there a tool that creates a basic HTML interface from an ABI?

I am looking for a tool that builds a basic interface for a contract so that I can use this generated HTML as a starting point to build the front end. I am aware that Mist, https://chriseth.github.io/...
mKoeppelmann's user avatar
  • 7,626
10 votes
2 answers
5k views

Storing private data on the ethereum blockchain

I plan to make an app utilising Ethereum that will store private data about a user. Eventually, I want this data to be accessible by selected users. I have seen conflicting answers & discussions ...
joe's user avatar
  • 269
10 votes
4 answers
797 views

How will dApps built on ETH deal with the requirements of GDPR?

GDPR expects it's citizens to have the 'right to be forgotten'. A company failing to fulfill this obligation is expected to pay a hefty fine. How will decentralized autonomous communities who store ...
Able Joseph's user avatar
9 votes
2 answers
5k views

How to connect a web site to a geth node?

Before the DApp-browser Mist was available, this web3 library seems the way to go on building a bridge from contract to a frontend (web site). But, I cannot get the very basic examples to work. ...
q9f's user avatar
  • 32.9k
9 votes
3 answers
10k views

How can I return dynamic string array in Solidity?

How can I return a dynamic string array? I came across serialization and deserialization. How can I serialize and deserialize dynamic string array ? pragma solidity ^0.5.0; contract Abc{ string[]...
ak07_'s user avatar
  • 153
9 votes
4 answers
13k views

How to call smart contract from html/Javascript

I want to have an html/Javascript code interact with a smart contract. Can someone please outline the basic/high level steps? I am seeing too many things spread across the net, finally confusing.
Ashish Sinha's user avatar
9 votes
1 answer
887 views

Is it possible to achieve anonymous mixing through the Ethereum protocol?

Are any developers working on anonymous mixing? Is it achievable through the development of either smart contracts or dapps? Is information leakage reduced or eliminated?
high110's user avatar
  • 4,756
9 votes
2 answers
3k views

should I use server side rendering(Next.js) for a dapp?

Recently I have been studying a lot about dapps and now working on a little complex one. So what I wanted to ask is which is better for a dapp ? SSR or CSR ? I have read in a couple of places that we ...
Ankit Brahmbhatt's user avatar
9 votes
1 answer
269 views

How many topics can a whisper message have?

I'm thinking in a new DAPP that may use whisper extensively. To evaluate the viability of the DAPP, I need to know if there is a limit on the number of topics that a whisper message can have. I would ...
jbaylina's user avatar
  • 775
9 votes
1 answer
665 views

Is a DAPP really decentralized? If so, what is decentralized exactly? [closed]

This is kind of a theoretical question with respect to Ethereum DAPPs which I have been trying to learn lately (and of which I will admit I am still woefully ignorant). Basically (using my limited ...
pQuestions123's user avatar
8 votes
2 answers
4k views

DApp storage for data other than tranactions?

For the purpose of illustration, say I would like to create a decentralized version of Yelp. A centralized approach would be to have a restaurants table and a reviews table in an Mysql database. In ...
jytoronto's user avatar
  • 195
8 votes
2 answers
5k views

What elements of a Dapp's backend are usually stored in a decentralised location?

I'm unclear as to what elements of a Dapp's backend code are actually decentralised. The following link states that a Dapp's backend is stored entirely on the blockchain. However, if I was to create ...
Harry Wright's user avatar
  • 1,171
8 votes
2 answers
2k views

Are tools like metamask putting decentralization in danger?

Does a tool like metamask, which connects your browser to a public ethereum node to simplify running DApps, put the basic idea of decentralization and trustless blockchain verification in danger? Is ...
q9f's user avatar
  • 32.9k
8 votes
2 answers
2k views

Will Ethereum be the Internet 2.0?

I've been following Ethereum since it was announced and I remember that the appeal was that it was "Bitcoin 2.0". While email replaced the post and Bitcoin replaced fiat, Ethereum would replace legal ...
rethsid's user avatar
  • 1,898
8 votes
1 answer
12k views

Where can I learn how to develop DApps using the solidity programming language? [closed]

What resources exist to help people learn the solidity programming language and create smart contracts & DApps on Ethereum?
Josh Stark's user avatar
  • 1,094
8 votes
1 answer
1k views

What reputation systems are implemented on Ethereum? [closed]

I'm looking into finding some sort of reputation system on Ethereum. Are there any projects out there already that do this? I found a DEVCON1 video about reputation systems and a few people discussing ...
linagee's user avatar
  • 6,158
8 votes
2 answers
7k views

Deploying contract from contract

I try something like this: Child.sol pragma solidity ^0.4.6; contract Child { address owner; function Child() { owner = msg.sender; } } Parent.sol pragma solidity ^0.4.6; import "./...
porfavorite's user avatar
8 votes
5 answers
2k views

When would it make sense to use node server for an application using smart contracts?

I am wondering if there are example cases where it would make sense to use a typical Node.js client-server app where the blockchain node would be running on the server. At first glance, this would ...
mcansado's user avatar
  • 841
7 votes
1 answer
26k views

I have two Metamask accounts with the same password and seed phrase. How is this possible?

So after doing a 'system restore' on my Ol' Faithful laptop, and reinstalling Chrome, my MMask extension was no longer there. Thankfully it's on mobile and I have the seed-phrase. The probs started ...
gIII's user avatar
  • 71

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