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The hcexplorer repository is a collection of golang packages and apps for Hcd data collection, storage, and presentation.

Repository overview

../hcexplorer              The hcexplorer daemon.
├── blockdata           Package blockdata.
├── cmd
│   ├── rebuilddb       rebuilddb utility, for SQLite backend.
│   ├── rebuilddb2      rebuilddb2 utility, for PostgreSQL backend.
│   └── scanblocks      scanblocks utility.
├── hcdataapi          Package hcdataapi for golang API clients.
├── db
│   ├── dbtypes         Package dbtypes with common data types.
│   ├── hcpg           Package hcpg providing PostgreSQL backend.
│   └── hcsqlite       Package hcsqlite providing SQLite backend.
├── public              Public resources for block explorer (css, js, etc.).
├── explorer            Package explorer, powering the block explorer.
├── mempool             Package mempool.
├── rpcutils            Package rpcutils.
├── semver              Package semver.
├── stakedb             Package stakedb, for tracking tickets.
├── txhelpers           Package txhelpers.
└── views               HTML templates for block explorer.

hcexplorer daemon

The root of the repository is the main package for the hcexplorer app, which has several components including:

  1. Block explorer (web interface).
  2. Blockchain monitoring and data collection.
  3. Mempool monitoring and reporting.
  4. Data storage in durable database (sqlite presently).
  5. RESTful JSON API over HTTP(S).

Block Explorer

After hcexplorer syncs with the blockchain server via RPC, by default it will begin listening for HTTP connections on This means it starts a web server listening on IPv4 localhost, port 7777. Both the interface and port are configurable. The block explorer and the JSON API are both provided by the server on this port. See JSON REST API for details.

Note that while hcexplorer can be started with HTTPS support, it is recommended to employ a reverse proxy such as nginx. See sample-nginx.conf for an example nginx configuration.

A new database backend using PostgreSQL was introduced in v0.9.0 that provides expanded functionality. However, initial population of the database takes additional time and tens of gigabytes of disk storage space. To disable the PostgreSQL backend (and the expanded functionality), hcexplorer may be started with the --lite (-l for short) command line flag.


The API serves JSON data over HTTP(S). All API endpoints are currently prefixed with /api (e.g. http://localhost:7777/api/stake), but this may be configurable in the future.

Endpoint List

Best block
Summary /block/best
Stake info /block/best/pos
Header /block/best/header
Hash /block/best/hash
Height /block/best/height
Size /block/best/size
Transactions /block/best/tx
Transactions Count /block/best/tx/count
Verbose block result /block/best/verbose
Block X (block index)
Summary /block/X
Stake info /block/X/pos
Header /block/X/header
Hash /block/X/hash
Size /block/X/size
Transactions /block/X/tx
Transactions Count /block/X/tx/count
Verbose block result /block/X/verbose
Block H (block hash)
Summary /block/hash/H
Stake info /block/hash/H/pos
Header /block/hash/H/header
Height /block/hash/H/height
Size /block/hash/H/size
Transactions /block/hash/H/tx
Transactions Count /block/hash/H/tx/count
Verbose block result /block/hash/H/verbose
Block range (X < Y)
Summary array for blocks on [X,Y] /block/range/X/Y
Summary array with block index step S /block/range/X/Y/S
Size (bytes) array /block/range/X/Y/size
Size array with step S /block/range/X/Y/S/size
Transaction T (transaction id)
Transaction Details /tx/T
Inputs /tx/T/in
Details for input at index X /tx/T/in/X
Outputs /tx/T/out
Details for output at index X /tx/T/out/X
Address A
Summary of last 10 transactions /address/A
Verbose transaction result for last
10 transactions
Summary of last N transactions /address/A/count/N
Verbose transaction result for last
N transactions
Stake Difficulty (Ticket Price)
Current sdiff and estimates /stake/diff
Sdiff for block X /stake/diff/b/X
Sdiff for block range [X,Y] (X <= Y) /stake/diff/r/X/Y
Current sdiff separately /stake/diff/current
Estimates separately /stake/diff/estimates
Ticket Pool
Current pool info (size, total value, and average price) /stake/pool
Pool info for block X /stake/pool/b/X
Pool info for block range [X,Y] (X <= Y) /stake/pool/r/X/Y?arrays=[true|false] *

*For the pool info block range endpoint that accepts the arrays url query, a value of true will put all pool values and pool sizes into separate arrays, rather than having a single array of pool info JSON objects. This may make parsing more efficient for the client.

Ticket fee rate summary /mempool/sstx
Ticket fee rate list (all) /mempool/sstx/fees
Ticket fee rate list (N highest) /mempool/sstx/fees/N
Detailed ticket list (fee, hash, size, age, etc.) /mempool/sstx/details
Detailed ticket list (N highest fee rates) /mempool/sstx/details/N
Status /status
Endpoint list (always indented) /list
Directory /directory

All JSON endpoints accept the URL query indent=[true|false]. For example, /stake/diff?indent=true. By default, indentation is off. The characters to use for indentation may be specified with the indentjson string configuration option.

Important Note About Mempool

Although there is mempool data collection and serving, it is very important to keep in mind that the mempool in your node (hcd) is not likely to be the same as other nodes' mempool. Also, your mempool is cleared out when you shutdown hcd. So, if you have recently (e.g. after the start of the current ticket price window) started hcd, your mempool will be missing transactions that other nodes have.

Command Line Utilities


rebuilddb is a CLI app that performs a full blockchain scan that fills past block data into a SQLite database. This functionality is included in the startup of the hcexplorer daemon, but may be called alone with rebuilddb.


rebuilddb2 is a CLI app used for maintenance of hcexplorer's hcpg database (a.k.a. DB v2) that uses PostgreSQL to store a nearly complete record of the Hcd blockchain data. See the for rebuilddb2 for important usage information.


scanblocks is a CLI app to scan the blockchain and save data into a JSON file. More details are in its own README. The repository also includes a shell script,, to convert the result into a comma-separated value (CSV) file.

Helper packages

package hcdataapi defines the data types, with json tags, used by the JSON API. This facilitates authoring of robust golang clients of the API.

package dbtypes defines the data types used by the DB backends to model the block, transaction, and related blockchain data structures. Functions for converting from standard Hcd data types (e.g. wire.MsgBlock) are also provided.

package rpcutils includes helper functions for interacting with a hcrpcclient.Client.

package stakedb defines the StakeDatabase and ChainMonitor types for efficiently tracking live tickets, with the primary purpose of computing ticket pool value quickly. It uses the database.DB type from with an ffldb storage backend from It also makes use of the stake.Node type from The ChainMonitor type handles connecting new blocks and chain reorganization in response to notifications from hcd.

package txhelpers includes helper functions for working with the common types hcutil.Tx, hcutil.Block, chainhash.Hash, and others.

Internal-use packages

Packages blockdata and hcsqlite are currently designed only for internal use internal use by other hcexplorer packages, but they may be of general value in the future.

blockdata defines:

  • The chainMonitor type and its BlockConnectedHandler() method that handles block-connected notifications and triggers data collection and storage.
  • The BlockData type and methods for converting to API types.
  • The blockDataCollector type and its Collect() and CollectHash() methods that are called by the chain monitor when a new block is detected.
  • The BlockDataSaver interface required by chainMonitor for storage of collected data.

hcpg defines:

  • The ChainDB type, which is the primary exported type from hcpg, providing an interface for a PostgreSQL database.
  • A large set of lower-level functions to perform a range of queries given a *sql.DB instance and various parameters.
  • The internal package contains the raw SQL statements.

hcsqlite defines:

  • A sql.DB wrapper type (DB) with the necessary SQLite queries for storage and retrieval of block and stake data.
  • The wiredDB type, intended to satisfy the APIDataSource interface used by the hcexplorer app's API. The block header is not stored in the DB, so a RPC client is used by wiredDB to get it on demand. wiredDB also includes methods to resync the database file.

package mempool defines a mempoolMonitor type that can monitor a node's mempool using the OnTxAccepted notification handler to send newly received transaction hashes via a designated channel. Ticket purchases (SSTx) are triggers for mempool data collection, which is handled by the mempoolDataCollector class, and data storage, which is handled by any number of objects implementing the MempoolDataSaver interface.


See the GitHub issue tracker and the project milestones.


  • Go 1.8.3 or newer.
  • Running hcd (>=1.1.0) synchronized to the current best block on the network.


Build from Source

The following instructions assume a Unix-like shell (e.g. bash).

  • Install Go

  • Verify Go installation:

    go env GOROOT GOPATH
  • Ensure $GOPATH/bin is on your $PATH

  • Install dep, the dependency management tool

    go get -u -v
  • Clone the hcexplorer repository

    git clone $GOPATH/src/
  • dep ensure, and build executable

    cd $GOPATH/src/
    dep ensure
    # build hcexplorer executable in workspace:
    go build
    # or to install hcexplorer and other tools into $GOPATH/bin:
    go install . ./cmd/...

The sqlite driver uses cgo, which requires gcc to compile the C sources. On Windows this is easily handled with MSYS2 (download and install MinGW-w64 gcc packages).

If you receive other build errors, it may be due to "vendor" directories left by dep builds of dependencies such as hcwallet. You may safely delete vendor folders and run dep ensure again.


First, update the repository (assuming you have master checked out):

cd $GOPATH/src/
git pull origin master
dep ensure
go build

Look carefully for errors with git pull, and reset locally modified files if necessary.

Getting Started

Create configuration file

Begin with the sample configuration file:

cp sample-hcexplorer.conf hcexplorer.conf

Then edit hcexplorer.conf with your hcd RPC settings.

Indexing the Blockchain

If hcexplorer has not previously been run with the PostgreSQL database backend, it is necessary to perform a bulk import of blockchain data and generate table indexes.

  • Create the hcexplorer user and database in PostgreSQL (tables will be created automatically).
  • Set your PostgreSQL credentials and host in both ./cmd/rebuilddb2/rebuilddb2.conf and ./hcexplorer.conf.
  • Run rebuilddb2 -u to bulk import and index.
  • In case of errors, or schema changes, the tables may be dropped with rebuilddb2 -D.

Starting hcexplorer

Finally, launch the hcexplorer daemon and allow the databases to sync new blocks. The SQLite database sync takes about an hour the first time. On subsequent launches, only new blocks are scanned.



Yes, please! See the file for details, but here's the gist of it:

  1. Fork the repo.
  2. Create a branch for your work (git branch -b cool-stuff).
  3. Code something great.
  4. Commit and push to your repo.
  5. Create a pull request.

Note that all community and team members are expected to adhere to the code of conduct, described in the CODE_OF_CONDUCT file.


This project is licensed under the ISC License. See the LICENSE file for details.


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