Esplora Block Explorer

Block explorer web interface based on the esplora-electrs HTTP API.

Written as a single-page app in a reactive and functional style using rxjs and cycle.js.

See live at Blockstream.info.

API documentation is available here.

Join the translation efforts on Transifex.

Features

• Explore blocks, transactions and addresses

• Support for Segwit and Bech32 addresses

• Shows previous output and spending transaction details

• Quick-search for txid, address, block hash or height by navigating to /<query>

• Advanced view with script hex/assembly, witness data, outpoints and more

• Mobile-ready responsive design

• Translated to 17 languages

• Noscript support

• For Liquid and other Elements-based chains: support for CT, peg-in/out transactions and multi-asset

• Mainnet, Testnet and Elements high performance electrum server

Developing

To start a development server with live babel/browserify transpilation, run:

$ git clone https://github.com/Blockstream/esplora && cd esplora
$ npm install
$ export API_URL=http://localhost:3000/ # or https://blockstream.info/api/ if you don't have a local API server
# (see more config options below)
$ npm run dev-server

The server will be available at http://localhost:5000/

To display debugging information for the Rx streams in the web developer console, set localStorage.debug = '*' and refresh.

Client polling

Browser polling uses three shared cadence tiers defined in client/src/const.js:

• Fast (30 seconds): chain tip, pending block templates, and recent mempool transactions shown on the dashboard and recent-transactions page.
• Standard (60 seconds): mempool summary, fee estimates, and pending peg transactions.
• Slow (10 minutes): the Bitcoin market chart, the Liquid high-value-assets panel, and a block-list safety poll used to detect same-height reorganizations.

View-scoped polls run only while their view is active and the browser window is focused. Their first tick occurs after a full interval because route entry already requests the initial data. This avoids sending duplicate requests when opening a page. The chain tip is global and also refreshes immediately when the application starts or a block, transaction, or address page is opened.

The block list refreshes when the chain tip height changes, with the slow safety poll covering same-height reorganizations. Confirmed peg state and peg chain transactions also refresh on new blocks rather than on a timer. A newly observed tip resets pending block template polling and delays the next request by 15 seconds so the electrs cache can refresh.

The dashboard requests both /mempool/recent and /mempool because they serve different UI contracts. /mempool/recent supplies the recent transaction list; /mempool supplies aggregate backlog fields such as transaction count, virtual size, total fees, and the fee histogram used by congestion and transaction fee analysis.

Building

To build the static assets directory for production deployment, set config options (see below) and run $ npm run dist. The files will be created under dist/.

Because Esplora is a single-page app, the HTTP server needs to be configured to serve the index.html file in reply to missing pages. See contrib/nginx.conf.in for example nginx configuration (TL;DR: try_files $uri /index.html).

Content-hashed frontend assets

Production builds create content-hashed copies of the app, stylesheets, lazy-loaded scripts and fonts referenced directly by the stylesheets by default. Original filenames are retained for rollback and cached HTML. asset-manifest.json in the output directory (dist/, or DEST) maps original relative paths to hashed paths. Set HASH_ASSETS=0 to disable hashing and use plain filenames without a manifest.

Both server-side renderers accept ASSET_MANIFEST pointing to this file (default: DEST/asset-manifest.json, or the project's dist/asset-manifest.json). Missing manifests fall back to plain filenames; STATIC_ROOT is applied to either form.

Deployment must upload new hashed files with Cache-Control: public, max-age=31536000, immutable before updating HTML, and must not delete old hashed files immediately after deployment (cached HTML and open tabs still reference them). If the server falls back to index.html for unknown paths, hashed-asset misses must return a real 404 instead, so a missing file is never cached as HTML.

Pre-rendering server (noscript)

To start a pre-rendering server that generates static HTML replies suitable for noscript users, run:

# (clone, cd, "npm install" and configure as above)

$ export STATIC_ROOT=http://localhost:5000/ # for loading CSS, images and fonts
$ npm run prerender-server

The server will be available at http://localhost:5001/

Configuration options

All options are optional.

GUI options

• NODE_ENV - set to production to enable js minification, or to development to disable (defaults to production)
• BASE_HREF - base href for user interface (defaults to /, change if not served from the root directory)
• BASE_PREFIX - optional path prefix prepended to each flavor's BASE_HREF, to serve the whole multi-network site under a sub-directory (e.g. BASE_PREFIX=preview serves /preview/, /preview/signet/, ...). API_URL is left un-prefixed so a prefixed build still uses the same backend
• STATIC_ROOT - root for static assets (defaults to BASE_HREF, change to load static assets from a different server)
• API_URL - URL for HTTP REST API (defaults to /api, change if the API is available elsewhere)
• CANONICAL_URL - absolute base url for user interface (optional, only required for opensearch and canonical link tags)
• NATIVE_ASSET_LABEL - the name of the network native asset (defaults to BTC)
• TARGET_BLOCK_INTERVAL_SECONDS - expected time between blocks, used for confirmation ETAs (defaults to 60 for Elements chains and 600 otherwise)
• SITE_TITLE - website title for <title> (defaults to Block Explorer)
• SITE_DESC - meta description (defaults to Esplora Block Explorer)
• HOME_TITLE - text for homepage title (defaults to SITE_TITLE)
• SITE_FOOTER - text for page footer (defaults to Powered by esplora)
• HEAD_HTML - custom html to inject at the end of <head>
• FOOT_HTML - custom html to inject at the end of <body>
• CUSTOM_ASSETS - space separated list of static assets to add to the build
• CUSTOM_CSS - space separated list of css files to append into style.css
• NOSCRIPT_REDIR - redirect noscript users to {request_path}?nojs (should be captured server-side and redirected to the prerender server, also see NOSCRIPT_REDIR_BASE in dev server options)
• NAVBAR_HTML - display navigation bar

Note that API_URL should be set to the publicly-reachable URL where the user's browser can issue requests at. (that is, not via localhost, unless you're setting up a dev environment where the browser is running on the same machine as the API server.)

Elements-only configuration:

• IS_ELEMENTS - set to 1 to indicate this is an Elements-based chain (enables asset issuance and Elements-specific features)
• SHOW_HIGH_VALUE_ASSETS - set to 1 to show circulating values for selected assets on the Liquid mainnet dashboard (enabled by the Liquid mainnet flavor)
• NATIVE_ASSET_ID - the ID of the native asset used to pay fees (defaults to 6f0279e9ed041c3d710a9f57d0c02928416460c4b722ae3457a11eec381c526d, the asset id for LBTC)
• BLIND_PREFIX - the base58 address prefix byte used for confidential addresses (defaults to 12)
• PARENT_CHAIN_EXPLORER_TXOUT - URL format for linking to transaction outputs on the parent chain, with {txid} and {vout} as placeholders. Example: https://blockstream.info/tx/{txid}#output:{vout}
• PARENT_CHAIN_EXPLORER_ADDRESS - URL format for linking to addresses on parent chain, with {addr} replaced by the address. Example: https://blockstream.info/address/{addr}
• ASSET_MAP_URL - url to load json asset map (in the "minimal" format)

Menu configuration (useful for inter-linking multiple instances on different networks):

• MENU_ITEMS - json map of menu items, where the key is the label and the value is the url
• MENU_ACTIVE - the active menu item identified by its label

Development server options

All GUI options, plus:

• PORT - port to bind http development server (defaults to 5000)
• CORS_ALLOW - value to set for Access-Control-Allow-Origin header (optional)
• NOSCRIPT_REDIR_BASE - base url for prerender server, for redirecting ?nojs requests (should be set alongside NOSCRIPT_REDIR)

Pre-rendering server options

All GUI options, plus:

• PORT - port to bind pre-rendering server (defaults to 5001)

Note that unlike the regular JavaScript-based app that sends API requests from the client-side, the pre-rendering server sends API requests from the server-side. This means that API_URL should be configured to the URL reachable by the server, typically http://localhost:3000/.

How to build the Docker image

Build the base image first:

docker build -t blockstream/esplora-base -f contrib/Dockerfile.base .

then the main image:

docker build -t esplora -f contrib/Dockerfile .

Alternatively, you may use the pre-built blockstream/esplora image from Docker Hub. The latest tag tracks the master branch; release tags (e.g. esplora_v2.10) are also published as versioned image tags (e.g. blockstream/esplora:v2.10) that can be pinned for reproducible deployments.

How to run the explorer for Bitcoin mainnet

docker run -p 50001:50001 -p 8080:80 \
           --volume $PWD/data_bitcoin_mainnet:/data \
           --rm -i -t esplora \
           bash -c "/srv/explorer/run.sh bitcoin-mainnet explorer"

How to run the explorer for Liquid mainnet

docker run -p 50001:50001 -p 8082:80 \
           --volume $PWD/data_liquid_mainnet:/data \
           --rm -i -t esplora \
           bash -c "/srv/explorer/run.sh liquid-mainnet explorer"

How to run the explorer for Bitcoin testnet3

docker run -p 50001:50001 -p 8084:80 \
           --volume $PWD/data_bitcoin_testnet:/data \
           --rm -i -t esplora \
           bash -c "/srv/explorer/run.sh bitcoin-testnet explorer"

How to run the explorer for Bitcoin testnet4

docker run -p 50001:50001 -p 8084:80 \
           --volume $PWD/data_bitcoin_testnet4:/data \
           --rm -i -t esplora \
           bash -c "/srv/explorer/run.sh bitcoin-testnet4 explorer"

How to run the explorer for Bitcoin signet

docker run -p 50001:50001 -p 8084:80 \
           --volume $PWD/data_bitcoin_signet:/data \
           --rm -i -t esplora \
           bash -c "/srv/explorer/run.sh bitcoin-signet explorer"

How to run the explorer for Liquid testnet

docker run -p 50001:50001 -p 8096:80 \
           --volume $PWD/data_liquid_testnet:/data \
           --rm -i -t esplora \
           bash -c "/srv/explorer/run.sh liquid-testnet explorer"

How to run the explorer for Liquid regtest

docker run -p 50001:50001 -p 8092:80 \
           --volume $PWD/data_liquid_regtest:/data \
           --rm -i -t esplora \
           bash -c "/srv/explorer/run.sh liquid-regtest explorer"

How to run the explorer for Bitcoin regtest

docker run -p 50001:50001 -p 8094:80 \
           --volume $PWD/data_bitcoin_regtest:/data \
           --rm -i -t esplora \
           bash -c "/srv/explorer/run.sh bitcoin-regtest explorer"

Regtest options

When run for Bitcoin regtest or Liquid regtest, the esplora container will create a default wallet and mine 100 blocks internally. You can disable this behavior by setting NO_REGTEST_MINING=1.

Docker config options

Set -e DEBUG=verbose to enable more verbose logging.

Set -e NO_PRECACHE=1 to disable pre-caching of statistics for "popular addresses", which may take a long time and is not necessary for personal use.

Set -e NO_ADDRESS_SEARCH=1 to disable the by-prefix address search index.

Set -e ENABLE_LIGHTMODE=1 to enable esplora-electrs's light mode.

Set -e ONION_URL=http://xyz.onion to enable the Onion-Location header.

Pull tor directly from Docker Hub - blockstream/tor:latest

Run: docker -d --name hidden_service blockstream/tor:latest tor -f /home/tor/torrc (could add a -v /extra/torrc:/home/tor/torrc, if you have a custom torrc)

Example torrc:

DataDirectory /home/tor/tor
PidFile /var/run/tor/tor.pid

ControlSocket /var/run/tor/control GroupWritable RelaxDirModeCheck
ControlSocketsGroupWritable 1
SocksPort unix:/var/run/tor/socks WorldWritable
SocksPort 9050

CookieAuthentication 1
CookieAuthFileGroupReadable 1
CookieAuthFile /var/run/tor/control.authcookie

Log [handshake]debug [*]notice stderr

HiddenServiceDir /home/tor/tor/hidden_service_v3/
HiddenServiceVersion 3
HiddenServicePort 80 127.0.0.1:80

License

MIT