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Polkadot-JS Tooling

Polkadot-JS is a collection of tools that interfaces with the Kusama blockchain in a granular way. Below we describe the different components of Polkadot-JS. For more information about Polkadot-JS you can consult the official documentation.

Polkadot-JS UI​

For Developers and Power Users Only

Please note that this wallet UI is oriented toward developers and power users. Explore Polkadot with a secure and user-friendly wallets listed on the Polkadot website. If you need help using the Polkadot-JS UI you can contact the Polkadot Support Team.

The Polkadot-JS UI is an application that loads in your browser. There is a standard DNS hosted version, which always has the latest features, and an IPFS version that is less frequently updated but is more decentralized. This is also often referred to as Polkadot-JS Apps, UI or the Apps UI. In the Wiki pages we will always refer to Polkadot-JS UI.

Polkadot-JS Apps has many capabilities that go beyond basic wallet functions such as account creation and sending or receiving transactions. See the dedicated section for more information about the UI.

Polkadot-JS UI Desktop App​

The Polkadot-JS UI also exists as a desktop application for Windows, Mac and Linux. The main advantage of using it is that by default it stores encrypted accounts on the filesystem instead of browser's local storage. Local storage is susceptible to attacks using XSS (Cross-Site Scripting). There's no such risk when with files stored on disk.

The desktop app uses the Electron framework. It provides the same features as web app, the only difference being different account storage.

Ledger not supported

The desktop application does not support Ledger accounts. If you need a cold storage solution you can try Parity Signer (aka Polkadot Vault).

Polkadot-JS Extension​

The Polkadot-JS browser extension is not a wallet per se but an account management tool. It allows you to create accounts and also import accounts from Ledger devices or Parity Signer, allowing the signing of extrinsics using these accounts. It also allows you export existing accounts and restore accounts (given you have the required information to restore them).

The extension is a robust key storage tool, i.e. even if you clear the cache of your browser your accounts will be retained. The extension will recognize any websites that have been flagged for malicious activity. For additional security, the extension will always ask if you want a specific website to access the account information on it.

The extension does not let users interact directly with on-chain functions as one would find on a wallet app like Metamask, i.e. it does not allow you to transact or do anything else other than adding and managing accounts. However, it provides a simple interface for interacting with extension-compliant dApps such as the Polkadot-JS UI and the Polkadot Staking Dashboard. Check wallets and extensions page for wallets that are capable of transacting on-chain directly.

Metadata Updates

The browser extension is a tool that interacts with the Polkadot network, but it is disconnected from it when it is not in use. It is important you always check for metadata updates before using the extension or other account management tools such as Parity Signer (aka Polkadot Vault).

Polkadot-JS Phishing List​

The Polkadot-JS phishing list website is a community-driven curation of malicious actors and operators. The Polkadot-JS extension uses this list to warn a user about suspicious URLs and addresses that are part of the list, and automatically blocks the account address.

Polkadot-JS API​

The Polkadot-JS API is a JavaScript API allowing for programs to interface with the functionalities of Kusama.

While interacting with the underlying @polkadot/api, most interfaces are generated automatically when connecting to an available node. This is quite a departure from many other API designs where the interfaces are commonly static.

When the API connects to a node, it initially retrieves the metadata which is used to "decorate" the API based on its contents. The metadata provides data in the form of api.<type>.<module>.<section> where type fits into one of the following categories:

  • consts - runtime constants (these are not functions so the values are returned directly as they are defined by the endpoint)
  • query - chain state values
  • tx - all extrinsics

The metadata also provides information on events, which can be queried using the api.query.system.events() interface.

None of the information contained within the api.{consts, query, tx}.<module>.<method> endpoints are hard-coded in the API. These values are defined by the decoration applied from the initial metadata response and are therefore completely dynamic. This suggests that when you connect to different parachains, the metadata and API decoration will change and provide varying interfaces based on the chain.

A developer can use Polkadot-JS Apps to test code's functionality. Interacting with the Polkadot-JS comes down to either querying on-chain data or issuing an extrinsic.

Querying On-chain Data​

To populate the Apps UI, the web app queries the Polkadot-JS API. The API then queries a Kusama node and uses JavaScript to return information that the UI will display on the screen. You can choose which node to connect to by changing it in the upper-left-hand corner of the screen.

Let's see how we can query on-chain data with Polkadot-JS UI on the Polkadot network with an example. To find out the current value for existential deposit, navigate to Developer > Chain state > Constants and query the balances pallet for existential deposit as shown in the snapshot below. You need to click on the plus button to execute the query. The value displayed is in plancks

query chain state

Issuing Extrinsics​

Extrinsics are pieces of information that come from outside the chain and are included in a block. Extrinsics can be one of three types: inherents, signed, and unsigned transactions.

Most extrinsics displayed on Polkadot-JS Apps are signed transactions. Inherits are non-signed and non-gossiped pieces of information included in blocks by the block author, such as timestamps, which are “true” because a sufficient number of validators have agreed about validity.

Unsigned transactions are information that does not require a signature but will require some sort of spam prevention, whereas signed transactions are issued by the originator account of a transaction which contains a signature of that account, which will be subject to a fee to include it on the chain.