Using the Hydra web wallet

IMPORTANT! When using a web wallet such as this one, please make 100% sure that you're entering the correct URL which is:

The Testnet Explorer can be viewed at:

The Testnet Faucet is at:

The Mainnet Explorer can be viewed at: https:/

There is no other URL being used for the web wallet, please be safe and verify the padlock with "Secure" in the URL field which validates the site:

Welcome to the HYDRA web wallet user documentation which will show

Introduction to the Web Wallet

The HYDRA web wallet runs in your browser and connects to the HYDRA network through a full node interface. The web wallet does not store your private keys so you must manage those with a downloaded Key File or seed words. This is completely your responsibility.

The web wallet may be launched by navigating to the site listed above.

Upon loading the web wallet, we get this very important warning, please take a few seconds and read it.

Welcome to the HYDRA web wallet! As shown below the left panel gives a menu with various options to create or restore a wallet, and other actions. The top of the menu gives seven choices for creating or restoring a wallet. The bottom of the menu gives various operations and configuration choices. The center part of the wallet page presents forms for data entry, viewing and management of the wallet assets.

The menu option Settings will allow selection of language and setting the wallet to work on Mainnet or Testnet. Select the desired network before restoring a wallet or entering a password.

The HYDRA web wallet works with HYDRA standard addresses which begin with a "H" (legacy), and is not compatible with SegWit (Segregated Witness) addresses that begin with an "M" (p2sh-segwit) or "qc1" (bech32).

Generate New Wallet - Restore Wallet

There are 7 ways to generate or restore a wallet.

  1. Generate new Wallet creates a new address and downloads a Key File

  2. Create from Mnemonic creates 12 seed words and a new address

  3. Restore from Mnemonic restores an address using 12 seed words from a desktop wallet

  4. Restore from WIF restores an address from a private key

  5. Restore from Key File restores an address from a Key File created by the web wallet

1. Generate New Wallet

Now let's choose the first option on the menu screen above and click on the red GENERATE NEW WALLET button. Next, you will enter a password which will be used to create a series of private keys. Write down a new long and strong password, enter the password and click the blue CONFIRM button:

3. Enter Password

Next click the large green button to download the Key File:

4. Download Key File

The Key File will download to your computer, save the file in a location you can find again and back up the file offline. The key file name will have a format like "1529379436736.txt" where the long number is the file creation time as Unix epoch time in milliseconds. You will need this Key File and the password to reload the wallet. If you lose the Key File or password, the funds in your wallet will be lost.

The View Wallet Info page will appear for your wallet where you can see:

  1. Address - receiving address for the wallet

  2. Balance - confirmed coins

  3. Unconfirmed Balance - coins waiting to be confirmed in the next block

  4. Private Key - the private key for this address

2. Create from Mnemonic

Click on the menu option Create from Mnemonic, GENERATE NEW WALLET, enter a password and click CONFIRM. The wallet will create a new address from 12 random seed words:

6. Generate Seed Words

Please write down and save these seed words, only you as the wallet user have access to these seed words (seed words and private keys aren't stored on the server, if you lose these seed words you'll lose access to your funds!).

Next you have to enter the seed words manually to confirm you have saved them. Click on the blue button I HAVE REMEMBERED ALL. LET'S CHECK, enter your password, re-enter the seed words and click the green CONFIRM button:

7. Confirm Seed Words

Then you will see the View Wallet Info page as shown above. You may want to download a Key File for the wallet using the menu option Dump as Key File which will give another way to restore the wallet as described in step 6 below.

3. Restore from Mnemonic

For the menu option Restore from Mnemonic you will enter the seed words saved in step 2 above. Make sure you enter the seed words correctly (with no typos or additional blank spaces), click the green CONFIRM button:

8. Enter Seed Words

After entering a new password, you will see the View Wallet Info page. Verify that the expected address was created. You may want to back up the wallet using the menu option Dump As Key File.

4. Restore from WIF

This choice allows restoring the wallet from a Wallet Input Format (WIF) private key such as from the web wallet, Hydra wallet or Hydra Electrum wallet. A WIF private key will be 52 characters long and has error checking and encoding (to reduce size) as compared with an original private key, which will be 64 hexadecimal characters.

Copy the WIF private key from another wallet. Select the menu option Restore from WIF, paste the private key into the WIF field and click the green CONFIRM button:

9. Restore from WIF

The View Wallet Info page will be displayed. Verify you restored the expected address. You may want to back up the wallet using the menu option Dump As Key File.

6. Restore from Key File

Select the menu option Restore from Key File, UPLOAD, select the key file to upload and click Open. Enter your password and click the blue CONFIRM button. The View Wallet Info page will be displayed.

Receive and Send HYDRA Coins


You can receive coins for the web wallet by sending them to the address of the wallet. Before you send any coins to the wallet make sure you can close and reopen the wallet with the same receive address. Using the menu option Dump as Key File and Restore from Key File is a safe way to do this. Using the menu option to restore from seed words to reopen the wallet is riskier because entering a typo for the seed words or password will create an unexpected random address.

On the View Wallet Info page click on the blue address COPY button and then paste this address as the receiving address in the sending wallet or account, and then send the coins. Wait a few minutes for the next block to be published and reload the web wallet to see the new balance. You can also click on the menu option View Wallet Txs to see the receiving transaction:


From your receiving wallet or account, copy the receiving address. On the web wallet menu, click Send and paste the receiving address into the Address* field, then enter the amount to send in the Amount* field (if you are sending an amount less than 1.0, use a leading zero, like "0.5", not ".5"). You can leave the Fee field set at the default of 0.01 (or set a lower fee if you understand how to do this) and click the green CONFIRM button:

The Please enter address again (Double check) page will be displayed. Copy and paste the receiving address into the Address field and click the blue CONFIRM button:

The You are going to send page will be displayed, after verifying the information click the blue CONFIRM button:

At the bottom of the screen you will see the green confirmation bar with a link to show the transaction in the Explorer:

Safe Send

A basic HYDRA transaction is composed of three steps:

  1. Compose the base transaction: from, to, amount, fee.

  2. Sign the transaction using the private key.

  3. Transmit the signed transaction to the network.

"Safe Send" isolates these steps between two computers/wallets, where step 2 is performed with an offline wallet whose private keys are never exposed to the internet. The web wallet "Safe Send" walks through these 3 steps to make a very safe transaction using the offline wallet.

Setup Offline Wallet

For a Safe Send, first set up the offline wallet by getting a copy of the web wallet and browser software. This example will use Google Chrome on Windows, and you can adjust to your preferred browser and operating system.

On the online computer, using the Chrome browser, go to In the browser upper right-hand corner select the three vertical dots for menu, select More tools then Save page as… to save the Hydra Web Wallet HTML file. This file contains all the JavaScript code to run the web wallet:

1 The Web Wallet HTML File The Web Wallet HTML file

To make an offline copy of Chrome, navigate to find the Chrome install folder on your computer. For Windows it is typically in Program Files (x86) - Google:

2019-42 Chrome Folder Copy Chrome folder

Copy the Chrome folder and Web Wallet HTML file to a USB thumb drive and then copy these to the offline computer.

Make sure that your offline computer has bluetooth disabled as well as any other outside connectivity. Use an untampered wired keyboard and mouse and insure there is no one around who can see or record your monitor. After offline setup, it is good practice to keep this computer offline or wipe the hard drive, unless you are completely sure that the machine is free of malware or security risks.

This gives a copy of the current Chrome and web wallet for the offline computer, and will not get any future version updates. You can do an update with these same steps, but it should not be necessary for these basic operations.

Launch the wallet in Offline Mode

On the offline computer, launch the Chrome browser: in the copied Chrome folder select User Data - Application - Chrome.exe:

2019-43 Select Chrome.exe (here in a folder called "Offline wallet")

Launch the offline web wallet

With the cursor in the Chrome URL address bar press Control - "O" (for Open) and then navigate to and Open the Hydra Web Wallet.html file:

Using the web wallet menu select Settings and in the Mode dropdown select Offline and CONFIRM:

From this point, you can generate a new wallet (suggested to create from mnemonic) and save (and backup) the key file. The menu will show Request Payment and the Request Payment page will show the receiving address for the offline wallet:

Copy the receiving address to a text file and copy to the USB thumb drive for transfer to the online computer. Now you can send Hydra to this address to fund the offline wallet.

This works to send Hydra to the offline wallet address because Hydra coins are actually stored as unspent transactions on the blockchain (no coins are ever stored in any wallet itself). However the offline wallet holds the private key for its address, and only the offline wallet can sign transactions to send HYDRA from its address.

Now we can use the 3 transaction steps for a Safe Send.

  1. Compose the base raw transaction with the online wallet.

From the online wallet menu select Safe Send and for step 1 fill in the addresses and amount. From Address* is the address of the offline wallet. The online wallet will query the blockchain for the "From Address" and select a previous transaction or transactions that hold sufficient Hydra for the amount being sent. Use 0.01 for the Fee unless you know how to choose lower fees.

After filling in all the fields, press CONFIRM, reenter the To Address*, press CONFIRM and CONFIRM again to create the raw transaction file:

2019-47 Step 1 Safe Send page Step 1 - creating the raw transaction

The online wallet will create a raw transaction text file, for example:

{"from":"<Hydra address>","to":"<Hydra address>","amount":"1000.0","fee":"0.01", "utxo":[{"address":"<from Hydra address>","txid":"<transaction ID>","confirmations":4, "isStake":false,"amount":10,"value":1000000000,"hash":"<hash checksum>","pos":0}]}

Here the online wallet has selected an appropriate unspent transaction owned by the "From Address" which holds 20000 Hydra.

You must leave the online wallet running at the end of step 1 while completing step 2 with the offline computer, then return for step 3. Exiting the online wallet at this point and reloading for step 3 will cancel the sequence.

Copy the raw transaction file to the offline wallet computer. For the offline wallet launch Chrome and the wallet in offline mode as in "Launch the Offline Wallet" above. Use the menu option Restore from Key File to load the previous address. The offline wallet will not know or display any balance.

  1. On the offline wallet menu select Safe Send and on the Safe Send page in step 1 press NEXT to begin step 2.

In step 2 select UPLOAD and open the raw transaction file copied from the online wallet. You will see the transaction fields as entered on the online computer. Select CONFIRM, reenter the To Address* and CONFIRM, and then CONFIRM again to create the signed tx file:

2019-48 Step 2 Step 2 - sign the raw transaction file to create the tx (transmission) file

The offline wallet will generate a signed tx file, for example:

{"from":"<Hydra Address>","to":"<Hydra Address>","amount":"1000.0", "fee":"0.01","rawTx":"<raw hex transaction code>"}

Copy this file to a USB thumb drive and transfer to the online wallet computer.

Note that the offline wallet is completely disconnected from the internet, and can only sign the transaction using its private keys. The offline wallet cannot even show the balance for its address, but you can see the balance with the Explorer.

  1. Back on the online wallet (still on the Safe Send page) on step 2 select NEXT to advance to step 3.

On step 3 select UPLOAD and open the signed tx file. You will see the transaction fields as entered in step 1. Press CONFIRM, reenter the Send To* address and select CONFIRM, and CONFIRM again to send the transaction to the network:

2019-49 Step 3 Step 3 - send the tx file to the network to complete the transaction


At the bottom of the screen you will see the green confirmation bar, and after the transaction is published in the next block select the Explorer link to see the transaction on the blockchain.

Send and Receive HRC20 Tokens

If you haven't done this, make sure you can back up the wallet using menu option Dump as Key File, and then reopen to the same address using Restore from Key File.

Receive HRC20 Tokens

To receive HRC20 tokens, on the web wallet View Wallet Info page and copy the Address field by clicking the COPY button, paste this address into the sending wallet or exchange, and send the tokens. After the next block publishes, reload the wallet to see the tokens:

Send HRC20 Tokens

To send HRC20 tokens you must have sufficient HYDRA coins in the address tied to that token. The web wallet default fee for sending tokens is 0.00000040 gas price x 250,000 gas = 0.1 HYDRA plus the default transaction fee of 0.01 HYDRA, for a total fee of 0.11 HYDRAS. You can use these default values unless you understand how to set lower values, but don't worry, any excess gas will be refunded as a mined amount (the mined amount must mature for 500 blocks before it can be sent or used for gas/fees).

25. Send HRC20 Token EN

Adding a HRC20 Token

The web wallet will has built-in capability for popular HRC20 tokens, and you can add additional tokens by entering the token's smart contract information. For example, if you want to add the XYZ token, find that token on the Explorer, copy the contract Address Hash field:

On the web wallet select the menu option Send, click the drop down next to "HYDRA", scroll to the bottom of the Coin/Token list and click the More... button:

27. Add HRC20 Token EN

Paste the Address Hash copied from the Explorer into the Token Contract Address field and click the blue SEARCH button:

28. Enter Address Hash EN