Groestlcoin 7th Anniversary Release

Groestlcoin News
8 min readMar 22, 2021

The past year of Groestlcoin must be the strangest year for the world in the existence of the coin so far. Covid-19 has and continues to dominate the headlines. Our hearts go out to everyone that has been affected by the virus, directly or indirectly.

This year has also seen a meteoric rise in Bitcoin and the total cryptocurrency market cap whilst the global economy almost grind to a halt in many industries. Many countries have implemented expensive policies to try to negate a recession, leading to a significant rise in new money being printed. On the brighter side, the development of Groestlcoin has been largely unaffected by the pandemic and we have a further 9 (12, including testnet) development updates to bring you today.

We will start with the brand new releases and then move on to the updates to existing applications which we are committed to keeping updated for security and functionality updates.

[ALL NEW] GRS (Wallet) Released — Testnet Version also available

GRS is a fast, easy, sexy Android mobile wallet. Sticking to our core philosophy we neither hold nor have access to users’ Groestlcoins. GRS is a real standalone server-less Groestlcoin client. Using SPV mode, GRS connects directly to the Groestlcoin network with the fast performance you need on a mobile device.

GRS is designed to protect you from malware, browser security holes and physical theft. With AES hardware encryption, app sandboxing and verified boot, GRS represents a significant security advance over web and desktop wallets.

Usually greater security inherently comes at the cost of the user experience, but GRS maintains a simple design principle to ensure a fantastic user experience with a simple and secure backup phrase, so your funds are never lost. Please store your secret phrase somewhere safe!


  • Simplified payment verification for fast mobile performance.
  • No server to get hacked or have downtime.
  • A single backup phrase that works forever.
  • Private keys never leave your device.
  • Import password-protected paper wallets.
  • Payment protocol payee identity certification.
  • Installation on rooted devices is strongly discouraged.

GRS is available in the Google Play Store, here:

GRS has also been developed for the Testnet, which is available from here:

Source Code:

[ALL NEW] GRS RPC Explorer (Mainnet + Testnet)

This explorer is a simple, no-database, self-hosted Groestlcoin block explorer via RPC to your own Groestlcoin Core node. It is easy to run and can be connected to other tools such as ElectrumX to achieve a full-featured explorer. Whatever reason one may have for running a full node (Trustlessness, technical curiosity, supporting the network etc.), it’s helpful to appreciate the “fullness” of your node. With this explorer, you can explore not just the blockchain database, but also explore the functional capabilities of your own node.


  • Network Summary dashboard
  • View details of blocks, transactions and addresses
  • Analysis tools for viewing stats on blocks, transactions and miner activity.
  • See raw JSON content from Groestlcoind used to generate most pages.
  • Search by the transaction ID, block hash/height, and address.
  • Optional transaction history for addresses by querying from ElectrumX.
  • Mempool summary, with the fee, size, and age breakdowns.
  • RPC command browser and terminal.

GRS RPC is available on

GRS RPC Testnet is available on

Source Code and instructions to connect your own node:

[ALL NEW] Groestlcoin Hardware Wallet Interface

GRS HWI is a Python library and command-line tool for interacting with hardware wallets. This interface provides a standard way for software to work with hardware wallets without needing to implement device-specific drivers. Caveat emptor: The inclusion of a specific hardware wallet vendor does not imply any endorsement of quality or security.


  • Support for Mainnet and Testnet
  • Support for KeepKey
  • Support for Ledger Nano S/X
  • Support for Trezor Model T/One
  • Open Source — MIT License

OSX Wallet:

Windows Installer:

Linux Installer:

Source Code:

[ALL NEW] Sparrow-GRS Wallet

Sparrow-GRS is a modern desktop Groestlcoin wallet application that supports most hardware wallets and has built on common standards such as PSBT, with an emphasis on transparency and usability.

This wallet does not hide information from you, and aims to provide as much detail as possible about your transactions and UTXOs, whilst also ensuring usability is not hindered.

Sparrow-GRS also includes a fully-featured transaction editor that also functions as a block explorer. This feature not only allows editing of all transaction fields but also provides easy inspection of the transaction bytes before broadcasting.


  • Full support for single-sig and multi-sig wallets on common script types
  • Connect to public Electrum-GRS servers
  • Standards-based including full PBST support
  • Support for KeepKey
  • Support for Ledger Nano S/X
  • Support for Trezor Model T/One
  • Full coin and fee control with comprehensive coin selection
  • Labelling of all transactions, inputs and outputs
  • Lightweight and multi-platform
  • Payjoin support
  • Built-in Tor
  • Testnet, Regtest and signet support

Download the OSX Wallet here:

Download Windows Installer here:

Download Linux (Ubuntu/Debian) Installer here:

Download Linux (Redhat/CentOS):

Source Code:

[ALL NEW] GRSPay Vault

GRSPay Server Vault allows web applications to access your hardware wallet. This enables a better-integrated user-experience.

GRSPay Value is a separate app, locally hosted on your own PC, which GRSPay Server connects to and asks for permission to access. Once permission is granted, GRSPay is able to integrate with any hardware wallet connected to your PC. You can import your wallet and spend incoming funds with a simple confirmation on your device with your keys never leaving your hardware device.


  • Support for Mainnet and Testnet
  • Support for KeepKey
  • Support for Ledger Nano S/X
  • Support for Trezor Model T / One
  • Asks permission before connecting
  • Built-in C#

Getting Started with GRSPay Vault

  1. Install and open GRSPay Value on your PC (Windows, MacOS or Linux)
  2. Plug in the hardware wallet and ensure it’s in wake-up state
  3. Go to GRSPay Server’s Store → General Settings → Wallet → Setup → Connect an existing wallet → Connect hardware wallet
  4. Grant Permission
  5. Your public key will be automatically imported into the store and configured to an appropriate format
  6. Validate that the address shown on GRSPay is the same as the one on your device
  7. Press Save

Spending funds with GRSPay Wallet

  1. Open GRSPay Value app on your PC
  2. Plug in the hardware wallet and ensure it is in wake-up state
  3. In GRSPay Server, go to Wallets → Manage → Send
  4. Fill in the Destination address and the amount
  5. Select Sign with a hardware wallet
  6. Verify the transaction on your hardware wallet and confirm it
  7. Broadcast the transaction

Note: OSX Build does not work with Safari, use Chrome or Firefox instead.

Download for OSX:

Download for Windows:

Download for Linux:

Source Code and more information:

[UPDATE] Electrum-GRS 4.0.9 [PC + Android version]

Electrum-GRS is one of the most popular desktop applications for PCs. It is a lightweight ‘thin client’ for Windows, MacOS and Linux based on a client-server protocol and we continue to update and support Electrum as a top priority.

Electrum-GRS is also available on Android and offers most of the same features as the PC equivalent but in a more portable form.

Change Log

  • Fix a regression introduced in 4.0.8, which prevented BIP70 invoices from being paid.
  • Reflect frozen channels and disconnected peers in the displayed ‘Can Send/Can Receive’ amounts.

Please ensure your secret phrase is kept somewhere safe.

Download the OSX Installer:

Download the Windows Installer:

Download the Windows standalone wallet:

Download the Windows Portable Version:

Download the Linux Installer here:

Download the Android version from the Google Play Store:

Source code:
Server Installer:

[UPDATE] GRSPay [Mainnet + Testnet]

GRSPay is a free and open-source cryptocurrency payment processor which allows you to receive payments in Groestlcoin with zero fees or middleman.

Change Log

  • New Wallet Setup UI
  • Hardware Wallet support for Groestlcoin

GRSPay is available at Please note that it is always safer and recommended to run your own GRSPay server for complete decentralisation and custom version control.

Source Code:

[UPDATE] Groestlcoin C-Lightning 0.9.3

C-Lightning is a light-weight, highly customisable and standard-compliant implementation of the Lightning Network protocol. C-lightning only works on Linux and Mac OS, and requires a locally (or remotely) running groestlcoind (version 2.16.0 or above) that is fully caught up with the network you’re testing on.

Change Log

  • Significantly improved parameter verification in Lightning-CLI, making it easier to debug why a call failed.
  • You can now query for the status of an invoice based on the hash or the invoice.
  • Plugins that are started while the node is running can now receive command-line arguments as if they were provided at the node start-up.
  • The security of the hsmtool used to encrypt and decrypt the node’s seed key was improved by switching to a passphrase prompt instead of a command-line argument.
  • Multiple plugins can not register for the db_write hook, which means you can now run multiple backup plugins at the same time. In addition, we wrote extensive documentation on how to secure your node from data loss.
  • No more reckless: the default network changed from testnet to Groestlcoin.
  • We have experimental support for the onion messages proposal, allowing arbitrary messages to be exchanged between nodes in the network.
  • We have experimental support for the offers proposal, enabling reusable invoices, refunds, invoices denominated in currencies other than Groestlcoin, and much more. If you’ve ever wanted to have an inline communication step with the other endpoint of payment, then take a look at this!
  • pyln now supports both receiving notifications from the RPC interface, as well as sending notifications in methods implemented by plugins. no more waiting in front of a blank screen for your users.
  • The new createInoive allows you to create an invoice externally, then have your node sign it and manage it internally.
  • You can use sendonionmessage to send an onion routed message, which recipients can receive using a plugin that registers for the onion_message or onion_message_blinded hook.

Download for Linux:

Download for OSX:

Source Code: