Mempool Explorer

Mempool is the same open-source code that runs mempool.space, self-hosted on your own node. Transaction lookups, fee estimates, and UTXO queries stay on your LAN and never reach a third party.

This guide builds Mempool v3.3.1 from source. The backend stores indexed data in MariaDB and serves the API on port 8999. Caddy puts the Angular frontend behind HTTPS on port 4080.

Requirements

• Electrum server running (Electrs on port 50001)
• Node.js 22 installed (from the BTC RPC Explorer guide or standalone via nodesource.com)
• Caddy installed (from the same guide or standalone via caddyserver.com)
• ~5 GB free on the SSD: build artefacts under /home/mempool/ take 4-5 GB; the MariaDB database starts small but grows to ~5 GB with full historical address indexing enabled

Create the user

A dedicated system user limits the blast radius of any bug. Adding it to the bitcoin group lets Mempool authenticate to Bitcoin Core via the cookie file, the same approach BTC RPC Explorer uses.

sudo adduser --disabled-password --gecos "" mempool
sudo adduser mempool bitcoin

Install build dependencies

Mempool's backend includes a Rust-native block-template builder (GBT). Debian 13 Trixie ships Rust 1.85, which meets the 1.84 requirement:

sudo apt install rustc cargo

Set up MariaDB

sudo apt install mariadb-server

Create the database and a dedicated user. Replace YourPasswordM with your password [M] (new, used only for MariaDB here):

sudo mysql <<'SQL'
CREATE DATABASE mempool;
GRANT ALL PRIVILEGES ON mempool.* TO 'mempool'@'localhost' IDENTIFIED BY 'YourPasswordM';
SQL

Install Mempool

Clone and check out the release as the mempool user:

sudo -u mempool bash <<'EOF'
git clone https://github.com/mempool/mempool ~/mempool
cd ~/mempool
git checkout v3.3.1
EOF

Configure the backend

Write the config file. Replace YourPasswordM with your password [M]:

sudo -u mempool tee /home/mempool/mempool/backend/mempool-config.json > /dev/null <<'CONFIG'
{
  "MEMPOOL": {
    "NETWORK": "mainnet",
    "BACKEND": "electrum",
    "HTTP_PORT": 8999,
    "SPAWN_CLUSTER_PROCS": 0,
    "API_URL_PREFIX": "/api/v1/",
    "POLL_RATE_MS": 2000,
    "CACHE_DIR": "./cache",
    "CACHE_ENABLED": true,
    "CLEAR_PROTECTION_MINUTES": 20,
    "RECOMMENDED_FEE_PERCENTILE": 50,
    "BLOCK_WEIGHT_UNITS": 4000000,
    "INITIAL_BLOCKS_AMOUNT": 8,
    "MEMPOOL_BLOCKS_AMOUNT": 8,
    "INDEXING_BLOCKS_AMOUNT": 0,
    "AUDIT": false,
    "RUST_GBT": true,
    "CPFP_INDEXING": false,
    "ALLOW_UNREACHABLE": true,
    "PRICE_UPDATES_PER_HOUR": 1
  },
  "CORE_RPC": {
    "HOST": "127.0.0.1",
    "PORT": 8332,
    "COOKIE": true,
    "COOKIE_PATH": "/data/bitcoin/.cookie"
  },
  "ELECTRUM": {
    "HOST": "127.0.0.1",
    "PORT": 50001,
    "TLS_ENABLED": false
  },
  "DATABASE": {
    "ENABLED": true,
    "HOST": "127.0.0.1",
    "PORT": 3306,
    "DATABASE": "mempool",
    "USERNAME": "mempool",
    "PASSWORD": "YourPasswordM"
  },
  "SOCKS5PROXY": {
    "ENABLED": false
  },
  "STATISTICS": {
    "ENABLED": true,
    "TX_PER_SECOND_SAMPLE_PERIOD": 150
  }
}
CONFIG

INDEXING_BLOCKS_AMOUNT: 0 disables historical address indexing on first run. Once the node is stable, raise it to 4320 (30 days) or 11000 (about 3 months) to unlock address balance history in the UI. Restart the service after changing it.

Build the backend

sudo su - mempool
cd ~/mempool/backend
npm install --prod
npm run build
exit

Build the frontend

sudo su - mempool
cd ~/mempool/frontend
npm install
npm run generate-themes
npm run generate-config
npm run ng -- build --configuration production
npm run sync-assets
exit

The built frontend lands in ~/mempool/frontend/dist/mempool/browser.

Autostart on boot

Back as user admin, create the service file:

sudo nano /etc/systemd/system/mempool.service

Paste:

# RaspiBolt: systemd unit for Mempool
# /etc/systemd/system/mempool.service

[Unit]
Description=Mempool Bitcoin Explorer
After=network.target bitcoind.service electrs.service mariadb.service

[Service]
WorkingDirectory=/home/mempool/mempool/backend
ExecStart=/usr/bin/node --max-old-space-size=2048 dist/index.js
User=mempool
Restart=on-failure
RestartSec=60
PrivateTmp=true
ProtectSystem=full
NoNewPrivileges=true
PrivateDevices=true

[Install]
WantedBy=multi-user.target

Enable and start:

sudo systemctl enable mempool
sudo systemctl start mempool
sudo journalctl -f -u mempool

Wait for a line containing Listening on http://127.0.0.1:8999/. On first start, Mempool syncs its database from Electrs and Bitcoin Core. Expect 30-60 minutes before fee charts and address lookups populate fully.

Press Ctrl-C to stop following the log.

HTTPS on the LAN with Caddy

Add a Mempool block to the Caddyfile (create the file first if Caddy was not already installed from the BTC RPC Explorer guide):

1. Open the Caddyfile:

   sudo nano /etc/caddy/Caddyfile

2. Add the Mempool block after your existing blocks:

   # Mempool Explorer
   :4080 {
     tls internal
   
     handle /api/* {
       reverse_proxy localhost:8999
     }
   
     handle {
       root * /home/mempool/mempool/frontend/dist/mempool/browser
       try_files {path} /index.html
       file_server
     }
   }

   The /api/* block proxies API calls to the backend. Everything else is served as a static file, falling back to index.html so Angular's client-side routing works for deep links.

3. Open the firewall and reload Caddy:

   sudo ufw allow 4080/tcp comment 'Mempool Explorer (Caddy)'
   sudo systemctl reload caddy

4. Point your browser at https://raspibolt.local:4080. Accept the one-time certificate warning.

Main takeaway: you now have a private Bitcoin block explorer and mempool visualizer. The node's own Electrs index answers every query.

Upgrade

Read the release notes before upgrading; some releases include a database migration.

sudo systemctl stop mempool

Switch to the mempool user and update the source:

sudo su - mempool
cd ~/mempool
git fetch
git checkout v<new-version>
exit

Rebuild the backend:

sudo su - mempool
cd ~/mempool/backend
npm install --prod
npm run build
exit

Rebuild the frontend:

sudo su - mempool
cd ~/mempool/frontend
npm install
npm run generate-themes
npm run generate-config
npm run ng -- build --configuration production
npm run sync-assets
exit

Start the service and confirm it's running:

sudo systemctl start mempool
sudo journalctl -u mempool --since "5 minutes ago"

Uninstall

sudo systemctl stop mempool
sudo systemctl disable mempool
sudo rm /etc/systemd/system/mempool.service
sudo ufw delete "allow 4080/tcp"

Remove the Mempool block from /etc/caddy/Caddyfile, then reload:

sudo systemctl reload caddy

Drop the database and user:

sudo mysql <<'SQL'
DROP DATABASE mempool;
DROP USER 'mempool'@'localhost';
SQL

If MariaDB is no longer needed:

sudo apt remove --purge mariadb-server mariadb-client
sudo apt autoremove

Remove the user and home directory:

sudo deluser mempool
sudo rm -rf /home/mempool